{"id":3423,"date":"2025-06-04T18:44:48","date_gmt":"2025-06-04T18:44:48","guid":{"rendered":"http:\/\/castco.wpenginepowered.com\/?post_type=case-study&#038;p=3423"},"modified":"2026-02-04T14:24:28","modified_gmt":"2026-02-04T14:24:28","slug":"outfall-safari","status":"publish","type":"case-study","link":"https:\/\/castco.org\/case-study\/outfall-safari\/","title":{"rendered":"Outfall Safari"},"content":{"rendered":"\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-9d6595d7 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:33.33%\">\n<div class=\"wp-block-group block is-layout-constrained wp-block-group-is-layout-constrained\">\n<h3 class=\"wp-block-heading\">Finding the unknown pollution sources<\/h3>\n\n\n\n<p class=\"has-text-align-left\">Pollution from surface water outfalls can harm our rivers, even in places where drains should carry only rainwater. Outfall Safaris help identify these hidden pollution sources.<\/p>\n\n\n\n<p class=\"has-text-align-left\">Trained volunteers survey riverbanks, while staff tackle harder-to-reach areas in the channel. The findings are shared with Thames Water, Catchment Partnerships, and the Environment Agency, helping guide clean-up efforts through Thames Water\u2019s Surface Water Outfall Programme (SWOP). It\u2019s a practical way for communities to protect their rivers.<\/p>\n\n\n\n<p><a href=\"https:\/\/castco.org\/knowledge-base\/method-audit-outfall-safari\/\">Outfall Safari is an officially audited CaSTCo method<\/a>.  <\/p>\n\n\n\n<p>You can find more training resources by visiting the official Outfall Safari webiste.<\/p>\n<\/div>\n\n\n\n<div class=\"wp-block-group block is-layout-constrained wp-block-group-is-layout-constrained\">\n<div class=\"wp-block-buttons is-layout-flex wp-block-buttons-is-layout-flex\">\n<div class=\"wp-block-button is-style-outline is-style-outline--1\"><a class=\"wp-block-button__link wp-element-button\" href=\"https:\/\/www.zsl.org\/what-we-do\/projects\/londons-rivers\">Find out more<\/a><\/div>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:66.66%\">\n<div class=\"wp-block-cover is-light vid-player has-primary-color has-text-color has-link-color\"><img decoding=\"async\" width=\"1024\" height=\"574\" class=\"wp-block-cover__image-background wp-image-4853 size-large lazyload\" alt=\"\" data-src=\"https:\/\/castco.org\/wp-content\/uploads\/2025\/06\/Screenshot-2026-02-04-at-9.22.46-AM-1024x574.jpg\" data-object-fit=\"cover\" data-srcset=\"https:\/\/castco.org\/wp-content\/uploads\/2025\/06\/Screenshot-2026-02-04-at-9.22.46-AM-1024x574.jpg 1024w, https:\/\/castco.org\/wp-content\/uploads\/2025\/06\/Screenshot-2026-02-04-at-9.22.46-AM-640x359.jpg 640w, https:\/\/castco.org\/wp-content\/uploads\/2025\/06\/Screenshot-2026-02-04-at-9.22.46-AM-768x431.jpg 768w, https:\/\/castco.org\/wp-content\/uploads\/2025\/06\/Screenshot-2026-02-04-at-9.22.46-AM-50x28.jpg 50w, https:\/\/castco.org\/wp-content\/uploads\/2025\/06\/Screenshot-2026-02-04-at-9.22.46-AM-1536x862.jpg 1536w, https:\/\/castco.org\/wp-content\/uploads\/2025\/06\/Screenshot-2026-02-04-at-9.22.46-AM-2048x1149.jpg 2048w, https:\/\/castco.org\/wp-content\/uploads\/2025\/06\/Screenshot-2026-02-04-at-9.22.46-AM-1280x718.jpg 1280w, https:\/\/castco.org\/wp-content\/uploads\/2025\/06\/Screenshot-2026-02-04-at-9.22.46-AM-1600x898.jpg 1600w, https:\/\/castco.org\/wp-content\/uploads\/2025\/06\/Screenshot-2026-02-04-at-9.22.46-AM-1920x1077.jpg 1920w, https:\/\/castco.org\/wp-content\/uploads\/2025\/06\/Screenshot-2026-02-04-at-9.22.46-AM-2560x1436.jpg 2560w, https:\/\/castco.org\/wp-content\/uploads\/2025\/06\/Screenshot-2026-02-04-at-9.22.46-AM.jpg 2674w\" data-sizes=\"(max-width: 1024px) 100vw, 1024px\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 1024px; --smush-placeholder-aspect-ratio: 1024\/574;\" \/><span aria-hidden=\"true\" class=\"wp-block-cover__background has-primary-background-color has-background-dim-0 has-background-dim\"><\/span><div class=\"wp-block-cover__inner-container is-layout-constrained wp-block-cover-is-layout-constrained\"> \n<div block-main-e3debd7dcad7bc3407a5477821df9855   class=\"block block-icons block-0 play\" id=\"block-main-e3debd7dcad7bc3407a5477821df9855\">\n    <svg class=\"icon icon-play\" role=\"presentation\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" viewBox=\"0 0 71.71 71.71\"><desc>play<\/desc><circle cx=\"35.86\" cy=\"35.85\" r=\"35.86\" fill=\"currentColor\"\/><path fill=\"#fff\" d=\"M29.86 22.41c.63.04 1.24.27 1.74.66l16 10.99c1 .5 1.4 1.72.89 2.72-.19.38-.51.7-.89.89l-16 10.98c-.5.4-1.11.63-1.74.65-1.15 0-2.07-.94-2.07-2.09 0-.07 0-.13.01-.2v-22.3c-.12-1.14.71-2.17 1.85-2.29.07 0 .14-.01.21-.01z\"\/><\/svg>\n<\/div>\n\n\n<!DOCTYPE html PUBLIC \"-\/\/W3C\/\/DTD HTML 4.0 Transitional\/\/EN\" \"http:\/\/www.w3.org\/TR\/REC-html40\/loose.dtd\">\n<html><body><figure class=\"wp-block-embed is-type-video is-provider-youtube wp-block-embed-youtube wp-embed-aspect-16-9 wp-has-aspect-ratio\"><div class=\"wp-block-embed__wrapper\">\n<div class=\"embed-container\"><iframe title=\"A short video guide to Outfall Safari 2026\" width=\"500\" height=\"281\" data-src=\"https:\/\/www.youtube-nocookie.com\/embed\/S0zo235qfZc?feature=oembed&amp;enablejsapi=1&amp;rel=0\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" class=\"lazyload\" data-load-mode=\"1\"><\/iframe><\/div>\n<\/div><\/figure>\n<\/body><\/html>\n<\/div><\/div>\n<\/div>\n<\/div>\n\n\n\n<div class=\"wp-block-group no-margin has-bg-alt-2-background-color has-background is-layout-constrained wp-block-group-is-layout-constrained\">\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-9d6595d7 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<h2 class=\"wp-block-heading has-text-align-center\"><strong>The problem: unexpected sewage leaking into rivers<\/strong><\/h2>\n\n\n\n<div class=\"wp-block-group is-layout-constrained wp-container-core-group-is-layout-b0c428d9 wp-block-group-is-layout-constrained\">\n<p class=\"has-text-align-center has-medium-font-size\">&nbsp;In many English towns and cities, sewage and rainwater flow through separate pipes. Sewage goes to treatment plants, and rainwater flows into rivers. But sometimes the systems get crossed (due to mistakes, blockages, or broken infrastructure), causing sewage to leak into rivers. Separate from sewage overflows, this &#8220;diffuse pollution&#8221; is an often overlooked driver of urban pollution. We still don\u2019t know how much they contribute, so more surveys of urban rivers are needed to better understand their impact.<\/p>\n\n\n\n<p class=\"has-text-align-center has-medium-font-size\">The magic of Outfall Safari is that it works with communities, who are the eyes on the ground, to pinpoint where further investigation is needed, and then works with those with the tools to help do something about it.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-9d6595d7 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<div class=\"wp-block-group block is-layout-constrained wp-block-group-is-layout-constrained\">\n<h2 class=\"wp-block-heading\"><strong>Who<\/strong><\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><a href=\"https:\/\/www.zsl.org\/what-we-do\/projects\/londons-rivers\">Zoological Society of London<\/a> \u2013 Outfall Safari Programme leader<br><\/li>\n\n\n\n<li><a href=\"https:\/\/www.thameswater.co.uk\/\">Thames Water<\/a> <strong>\u2013<\/strong> Funder with data guiding investment into removing sources of pollution. <br><\/li>\n\n\n\n<li>Delivered with local Catchment Partnerships (<a href=\"https:\/\/www.thames21.org.uk\/\">Thames21<\/a>, <a href=\"http:\/\/South East Rivers Trust: Home South East Rivers Trust https:\/\/www.southeastriverstrust.org\">South East Rivers Trust<\/a>), NGOs (including <a href=\"https:\/\/theriverstrust.org\/\">Rivers Trusts<\/a>), the <a href=\"https:\/\/www.gov.uk\/government\/organisations\/environment-agency\">Environment Agency<\/a>,<a href=\"https:\/\/www.gov.uk\/government\/organisations\/environment-agency\"> <\/a>and community groups across the Thames catchment<\/li>\n<\/ul>\n<\/div>\n<\/div>\n\n\n\n<div class=\"wp-block-column has-bg-color has-secondary-background-color has-text-color has-background has-link-color wp-elements-8236fafc05b21d264e7ffa823164abd1 is-layout-flow wp-block-column-is-layout-flow\">\n<div class=\"wp-block-group block is-layout-constrained wp-block-group-is-layout-constrained\">\n<h2 class=\"wp-block-heading\">Where<\/h2>\n\n\n\n<p>Outfall Safais take place on four rivers across Greater London each year. Every river in London is surveyed in a 4-year cycle.<\/p>\n\n\n\n<figure class=\"wp-block-image aligncenter size-full is-resized\"><img decoding=\"async\" width=\"1080\" height=\"1920\" data-src=\"https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Copy-of-Untitled-Your-Story.png\" alt=\"\" class=\"wp-image-3436 lazyload\" style=\"--smush-placeholder-width: 1080px; --smush-placeholder-aspect-ratio: 1080\/1920;width:200px;height:auto\" data-srcset=\"https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Copy-of-Untitled-Your-Story.png 1080w, https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Copy-of-Untitled-Your-Story-640x1138.png 640w, https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Copy-of-Untitled-Your-Story-1024x1820.png 1024w, https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Copy-of-Untitled-Your-Story-768x1365.png 768w, https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Copy-of-Untitled-Your-Story-28x50.png 28w, https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Copy-of-Untitled-Your-Story-864x1536.png 864w\" data-sizes=\"(max-width: 1080px) 100vw, 1080px\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" \/><\/figure>\n<\/div>\n<\/div>\n<\/div>\n\n\n \n<div block-main-c74822a099e05219d964fafb6eefd9eb   class=\"block block-image-slider block-0 block--style-full-image-width\" id=\"block-main-c74822a099e05219d964fafb6eefd9eb\">\n    \n<div class=\"slider\" data-flickity='{\"autoPlay\":false,\"selectedAttraction\":0.025,\"prevNextButtons\":true,\"wrapAround\":true,\"arrowShape\":\"M59.4,63.5c-0.8-1.2-14.3-10.7,0.1-27L76,19.1L58,0l-20,21.1C19.1,41,19.4,59.4,38.5,79.4L58,100L76,80.9L59.5,63.5 c0,0,0,0-0.1-0.1L59.4,63.5z\",\"contain\":true,\"pageDots\":true,\"adaptiveHeight\":true}'>    <figure class=\"slide slide-1\">\n            <figcaption><p>Presenting our findings  to our community and partners<\/p><\/figcaption>\n            <a href=\"https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Picture2.jpg\" title=\"Presenting our findings  to our community and partners\" class=\"gallery-item\"><img decoding=\"async\" width=\"592\" height=\"446\" data-src=\"https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Picture2.jpg\" class=\"attachment-xl size-xl lazyload\" alt=\"\" data-sizes=\"(min-width: 1420px) 1420px, 100vw\" data-srcset=\"https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Picture2.jpg 592w, https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Picture2-50x38.jpg 50w\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 592px; --smush-placeholder-aspect-ratio: 592\/446;\" \/><\/a>\n    <\/figure>    <figure class=\"slide slide-2\">\n            <figcaption><p>A potential source of diffuse pollution in the Thames River?<\/p><\/figcaption>\n            <a href=\"https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Screen-Shot-2025-05-20-at-11.06.52-AM.png\" title=\"A potential source of diffuse pollution in the Thames River?\" class=\"gallery-item\"><img decoding=\"async\" width=\"440\" height=\"476\" data-src=\"https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Screen-Shot-2025-05-20-at-11.06.52-AM.png\" class=\"attachment-xl size-xl lazyload\" alt=\"\" data-sizes=\"(min-width: 1420px) 1420px, 100vw\" data-srcset=\"https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Screen-Shot-2025-05-20-at-11.06.52-AM.png 440w, https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Screen-Shot-2025-05-20-at-11.06.52-AM-46x50.png 46w\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 440px; --smush-placeholder-aspect-ratio: 440\/476;\" \/><\/a>\n    <\/figure>    <figure class=\"slide slide-3\">\n            <figcaption><p>Presenting our findings  to our community and partners<\/p><\/figcaption>\n            <a href=\"https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Picture1.jpg\" title=\"Presenting our findings  to our community and partners\" class=\"gallery-item\"><img decoding=\"async\" width=\"479\" height=\"638\" data-src=\"https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Picture1.jpg\" class=\"attachment-xl size-xl lazyload\" alt=\"\" data-sizes=\"(min-width: 1420px) 1420px, 100vw\" data-srcset=\"https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Picture1.jpg 479w, https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Picture1-38x50.jpg 38w\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 479px; --smush-placeholder-aspect-ratio: 479\/638;\" \/><\/a>\n    <\/figure>    <figure class=\"slide slide-4\">\n            <figcaption><p>In-channel Outfall Safari survey<\/p><\/figcaption>\n            <a href=\"https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Picture4.jpg\" title=\"In-channel Outfall Safari survey\" class=\"gallery-item\"><img decoding=\"async\" width=\"440\" height=\"592\" data-src=\"https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Picture4.jpg\" class=\"attachment-xl size-xl lazyload\" alt=\"\" data-sizes=\"(min-width: 1420px) 1420px, 100vw\" data-srcset=\"https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Picture4.jpg 440w, https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Picture4-37x50.jpg 37w\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 440px; --smush-placeholder-aspect-ratio: 440\/592;\" \/><\/a>\n    <\/figure>    <figure class=\"slide slide-5\">\n            <figcaption><p>PSWO CCTV (credit Thames Water)<\/p><\/figcaption>\n            <a href=\"https:\/\/castco.org\/wp-content\/uploads\/2025\/06\/PSWO-CCTV-credit-Thames-Water.png\" title=\"PSWO CCTV (credit Thames Water)\" class=\"gallery-item\"><img decoding=\"async\" width=\"570\" height=\"740\" data-src=\"https:\/\/castco.org\/wp-content\/uploads\/2025\/06\/PSWO-CCTV-credit-Thames-Water.png\" class=\"attachment-xl size-xl lazyload\" alt=\"\" data-sizes=\"(min-width: 1420px) 1420px, 100vw\" data-srcset=\"https:\/\/castco.org\/wp-content\/uploads\/2025\/06\/PSWO-CCTV-credit-Thames-Water.png 570w, https:\/\/castco.org\/wp-content\/uploads\/2025\/06\/PSWO-CCTV-credit-Thames-Water-39x50.png 39w\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 570px; --smush-placeholder-aspect-ratio: 570\/740;\" \/><\/a>\n    <\/figure>\n<\/div>\n<\/div>\n\n\n\n<div class=\"wp-block-columns are-vertically-aligned-top has-highlight-background-color has-background is-layout-flex wp-container-core-columns-is-layout-9d6595d7 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-vertically-aligned-top has-bg-alt-2-background-color has-background is-layout-flow wp-block-column-is-layout-flow\">\n<div class=\"wp-block-group block is-layout-constrained wp-block-group-is-layout-constrained\">\n<h2 class=\"wp-block-heading\"><strong>The tools in our method<\/strong><\/h2>\n\n\n\n<p><span style=\"box-sizing: border-box; margin: 0px; padding: 0px;\"><strong>Volunteer training:<\/strong>&nbsp;Volunteers attended a 2-hour, ZSL-<\/span>led training session that included an overview of local river pollution issues, instructions on how to assess outfalls, a Health and Safety briefing, information on how the survey is coordinated, and apportionment of reaches to volunteers for the survey.<\/p>\n\n\n\n<p><strong>Bankside surveys: <\/strong>Volunteers selected the reach of the river they would like to survey. Their surveys involved walking along a chosen section of the river with the Outfall Safari app, locating outfalls, and scoring them using the Water UK and EA assessment questions.<\/p>\n\n\n\n<p><strong>In-channel surveys: <\/strong>Once volunteers completed their surveys, ZSL staff filled in any gaps where surveying was not possible from the bank by going in-river and locating and ranking the pollution using the same method.<\/p>\n\n\n\n<p><strong>Data processing: <\/strong>ZSL coordinated the survey and gave feedback to volunteers as the survey progressed, via <a href=\"https:\/\/padlet.com\/\" target=\"_blank\" rel=\"noreferrer noopener\">Padlet<\/a>. All data uploaded from the river was checked for accuracy before final reporting to Thames Water, Catchment Partnerships and Environment Agency.<\/p>\n<\/div>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-vertically-aligned-top has-primary-color has-highlight-background-color has-text-color has-background has-link-color wp-elements-5fd49d18174552f3a8eb357148f016b5 is-layout-flow wp-block-column-is-layout-flow\">\n<div class=\"wp-block-group block is-layout-constrained wp-block-group-is-layout-constrained\">\n<div class=\"wp-block-group is-layout-constrained wp-block-group-is-layout-constrained\">\n<div class=\"wp-block-group is-layout-constrained wp-block-group-is-layout-constrained\">\n<p class=\"no-margin-bottom has-large-font-size\"><strong>4,465<\/strong><\/p>\n\n\n\n<p class=\"no-margin-top\"><strong>outfall assessments conducted<\/strong><\/p>\n<\/div>\n\n\n\n<div class=\"wp-block-group is-layout-constrained wp-block-group-is-layout-constrained\">\n<div style=\"height:12px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<p class=\"no-margin-bottom has-large-font-size\"><strong>671 km<\/strong><\/p>\n\n\n\n<p class=\"no-margin-top\"><strong>of river surveyed<\/strong><\/p>\n<\/div>\n\n\n\n<div style=\"height:12px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<div class=\"wp-block-group is-layout-constrained wp-block-group-is-layout-constrained\">\n<p class=\"no-margin-bottom has-large-font-size\"><strong>490 <\/strong><\/p>\n\n\n\n<p class=\"no-margin-top\"><strong>volunteers engaged<\/strong><\/p>\n<\/div>\n\n\n\n<div style=\"height:12px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<div class=\"wp-block-group is-layout-constrained wp-block-group-is-layout-constrained\">\n<p class=\"no-margin-bottom has-large-font-size\"><strong>65%<\/strong><\/p>\n\n\n\n<p class=\"no-margin-top\"><strong>of the outfalls on SWOP in AMP7 were reported via Outfall Safari<\/strong><\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n<div class=\"wp-block-group is-layout-constrained wp-block-group-is-layout-constrained\">\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-9d6595d7 wp-block-columns-is-layout-flex\"><\/div>\n<\/div>\n\n\n\n<div class=\"wp-block-group is-layout-constrained wp-block-group-is-layout-constrained\">\n<div class=\"wp-block-columns are-vertically-aligned-center is-layout-flex wp-container-core-columns-is-layout-9d6595d7 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-vertically-aligned-center is-layout-flow wp-block-column-is-layout-flow\">\n<h2 class=\"wp-block-heading\">Results <\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Identified 638 polluting outfalls (outfalls scoring \u2265 6)<br><\/li>\n\n\n\n<li>Identified 162 highly polluting outfalls (outfalls scoring \u226510) that have been reported from the river for immediate action to stop the source of pollution<br><\/li>\n\n\n\n<li>Found, on average across London, one polluted surface water outfall (PSWO) per km of river surveyed and evidenced the worst-impacted river in terms of density of PSWOs<br><\/li>\n\n\n\n<li>Fed data into the <a href=\"https:\/\/apps.london.gov.uk\/river-health\/\">Greater London Authorities\u2019 River Health Map<\/a> and the London Mayor\u2019s plan for cleaning up rivers<br><\/li>\n\n\n\n<li>Directed Thames Water investment into resolving the polluted surface water outfalls problem. Approximately 65% of the outfalls on <a href=\"https:\/\/www.arcgis.com\/home\/item.html?id=9e2d623c523941169c02bf5294285847\">Surface Water Outfall Programme<\/a> (SWOP) in <a href=\"https:\/\/www.thameswater.co.uk\/media-library\/home\/about-us\/regulation\/our-five-year-plan\/pr24-2023\/completion-of-amp7-winep.pdf\">AMP7<\/a> were reported via Outfall Safari!<\/li>\n<\/ul>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-vertically-aligned-center is-layout-flow wp-block-column-is-layout-flow\">\n<figure class=\"wp-block-image size-full is-resized\"><img decoding=\"async\" width=\"696\" height=\"501\" data-src=\"https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Picture3.png\" alt=\"\" class=\"wp-image-3454 lazyload\" style=\"--smush-placeholder-width: 696px; --smush-placeholder-aspect-ratio: 696\/501;width:556px;height:auto\" data-srcset=\"https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Picture3.png 696w, https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Picture3-640x461.png 640w, https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Picture3-50x36.png 50w\" data-sizes=\"(max-width: 696px) 100vw, 696px\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" \/><\/figure>\n<\/div>\n<\/div>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<div class=\"wp-block-group is-layout-constrained wp-block-group-is-layout-constrained\">\n<div class=\"wp-block-columns are-vertically-aligned-center is-layout-flex wp-container-core-columns-is-layout-9d6595d7 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-vertically-aligned-center is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:33.33%\">\n<figure class=\"wp-block-image size-full is-style-default\"><img decoding=\"async\" width=\"636\" height=\"360\" data-src=\"https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Picture7-1.png\" alt=\"\" class=\"wp-image-3463 lazyload\" data-srcset=\"https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Picture7-1.png 636w, https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Picture7-1-50x28.png 50w\" data-sizes=\"(max-width: 636px) 100vw, 636px\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 636px; --smush-placeholder-aspect-ratio: 636\/360;\" \/><\/figure>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-vertically-aligned-center is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:66.66%\">\n<h2 class=\"wp-block-heading\">Key learnings<\/h2>\n\n\n\n<p>Although Outfall Safari was originally developed to identify misconnections, it has also helped highlight other pollution sources from <strong>polluted surface water outfalls (PSWOs)<\/strong>, such as blockages and failing infrastructure. <\/p>\n\n\n\n<p><em>Table 3 shows the causes of PSWO pollution in London that Thames Water addressed during Asset Management Period 7 (2020\u20132025)<\/em>.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">What we learned<\/h4>\n\n\n\n<p>Even in the absence of a SWOP, quantifying the scale of pollution can help make the case for water company investment and prioritisation of this issue.<\/p>\n\n\n\n<p>We found that flexibility is essential when teaching the Outfall Safari method, as not all water companies have a Surface Water Outfall Programme (SWOP) like Thames Water.<br><\/p>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n<div style=\"height:62px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n<\/div>\n\n\n\n<div class=\"wp-block-cover is-light add-cover-padding\" style=\"min-height:451px;aspect-ratio:unset;\"><img decoding=\"async\" class=\"wp-block-cover__image-background wp-image-99 lazyload\" alt=\"\" data-src=\"https:\/\/castco.org\/wp-content\/uploads\/2024\/08\/section-bkground-2.png\" style=\"--smush-placeholder-width: 1920px; --smush-placeholder-aspect-ratio: 1920\/999;object-position:50% 100%\" data-object-fit=\"cover\" data-object-position=\"50% 100%\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" \/><span aria-hidden=\"true\" class=\"wp-block-cover__background has-background-dim\" style=\"background-color:#fafef1\"><\/span><div class=\"wp-block-cover__inner-container is-layout-constrained wp-block-cover-is-layout-constrained\">\n<div class=\"wp-block-group is-layout-constrained wp-block-group-is-layout-constrained\">\n<h2 class=\"wp-block-heading textalign-center\"><strong>Deep dive<\/strong>: Pollution sources found using Outfall Safari<\/h2>\n\n\n\n<div class=\"wp-block-columns are-vertically-aligned-center is-layout-flex wp-container-core-columns-is-layout-9d6595d7 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-vertically-aligned-center is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:33.33%\">\n<figure class=\"wp-block-image size-full is-resized\"><img decoding=\"async\" width=\"718\" height=\"922\" data-src=\"https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Screen-Shot-2025-05-20-at-11.07.32-AM-1.png\" alt=\"\" class=\"wp-image-3498 lazyload\" style=\"--smush-placeholder-width: 718px; --smush-placeholder-aspect-ratio: 718\/922;width:356px;height:auto\" data-srcset=\"https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Screen-Shot-2025-05-20-at-11.07.32-AM-1.png 718w, https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Screen-Shot-2025-05-20-at-11.07.32-AM-1-640x822.png 640w, https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Screen-Shot-2025-05-20-at-11.07.32-AM-1-39x50.png 39w\" data-sizes=\"(max-width: 718px) 100vw, 718px\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" \/><\/figure>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-vertically-aligned-center is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:66.66%\">\n<h3 class=\"wp-block-heading\"><strong>Misconnected pipework<\/strong><\/h3>\n\n\n\n<p>Between 2020 &#8211; 2025, volunteers found 1,314 incidents of misconnected appliances and\/or defected pipework. These physical miconnections and defects are some of the greatest threats to water quality, sending pollution into rivers and compromising the biodiversity and amenity value of waterways.<\/p>\n\n\n\n<p>Using the Outfall Safari app, volunteers completed an assessment form, with answers converted into an impact score with a max of 20. If the score is greater than or equal to 10, volunteers immediately report to the water company for urgent attention.<\/p>\n\n\n\n<p>Once reported to Thames Water, their Network Operations and Environmental Protection Team work to trace the source of the pollution.<\/p>\n<\/div>\n<\/div>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<div class=\"wp-block-columns are-vertically-aligned-center is-layout-flex wp-container-core-columns-is-layout-9d6595d7 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-vertically-aligned-center is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:33.33%\">\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" width=\"904\" height=\"560\" data-src=\"https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Screen-Shot-2025-05-20-at-11.06.18-AM.png\" alt=\"\" class=\"wp-image-3505 lazyload\" data-srcset=\"https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Screen-Shot-2025-05-20-at-11.06.18-AM.png 904w, https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Screen-Shot-2025-05-20-at-11.06.18-AM-640x396.png 640w, https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Screen-Shot-2025-05-20-at-11.06.18-AM-768x476.png 768w, https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Screen-Shot-2025-05-20-at-11.06.18-AM-50x31.png 50w\" data-sizes=\"(max-width: 904px) 100vw, 904px\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 904px; --smush-placeholder-aspect-ratio: 904\/560;\" \/><\/figure>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-vertically-aligned-center is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:66.66%\">\n<h3 class=\"wp-block-heading\"><strong>Missing surface water caps<\/strong><\/h3>\n\n\n\n<p>Between 2020 &#8211; 2025, volunteers found 500 incidents of missing private surface water caps. <\/p>\n\n\n\n<p>These are blockages that specifically occur in a customer&#8217;s private drainage system, before they reach the sewers. Often, the blockage can lead to sewage overflowing and entering the surface water systems, polluting the local watercourse.<\/p>\n\n\n\n<p>In the photo, you can see the numerous ways in which Thames Water remediated such incidents!<\/p>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<div class=\"wp-block-columns are-vertically-aligned-center is-layout-flex wp-container-core-columns-is-layout-9d6595d7 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-vertically-aligned-center is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:33.33%\">\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" width=\"914\" height=\"504\" data-src=\"https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Screen-Shot-2025-05-20-at-11.06.05-AM-1.png\" alt=\"\" class=\"wp-image-3485 lazyload\" data-srcset=\"https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Screen-Shot-2025-05-20-at-11.06.05-AM-1.png 914w, https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Screen-Shot-2025-05-20-at-11.06.05-AM-1-640x353.png 640w, https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Screen-Shot-2025-05-20-at-11.06.05-AM-1-768x423.png 768w, https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Screen-Shot-2025-05-20-at-11.06.05-AM-1-50x28.png 50w\" data-sizes=\"(max-width: 914px) 100vw, 914px\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 914px; --smush-placeholder-aspect-ratio: 914\/504;\" \/><\/figure>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-vertically-aligned-center is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:66.66%\">\n<h3 class=\"wp-block-heading\"><strong>Private blockages<\/strong><\/h3>\n\n\n\n<p>Between 2020 &#8211; 2025, volunteers found 291 incidents of private blockages.<\/p>\n\n\n\n<p>These incidents involve private properties where surface water caps are missing. This can cause sewage to enter the open cap and be discharged to the local watercourse, polluting surface waters and causing harm to local aquatic life and river biodiversity.<\/p>\n\n\n\n<p>To remediate this, Thames Water offered to replace the cap free of charge to the customer. Permission is needed to do this. <\/p>\n\n\n\n<p><\/p>\n<\/div>\n<\/div>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<div class=\"wp-block-columns are-vertically-aligned-center is-layout-flex wp-container-core-columns-is-layout-9d6595d7 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-vertically-aligned-center is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:33.33%\">\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" width=\"2722\" height=\"2007\" data-src=\"https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/who-is-responsible-diagram.png\" alt=\"\" class=\"wp-image-3504 lazyload\" data-srcset=\"https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/who-is-responsible-diagram.png 2722w, https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/who-is-responsible-diagram-640x472.png 640w, https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/who-is-responsible-diagram-1024x755.png 1024w, https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/who-is-responsible-diagram-768x566.png 768w, https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/who-is-responsible-diagram-50x37.png 50w, https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/who-is-responsible-diagram-1536x1133.png 1536w, https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/who-is-responsible-diagram-2048x1510.png 2048w, https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/who-is-responsible-diagram-1280x944.png 1280w, https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/who-is-responsible-diagram-1600x1180.png 1600w, https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/who-is-responsible-diagram-1920x1416.png 1920w, https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/who-is-responsible-diagram-2560x1888.png 2560w\" data-sizes=\"(max-width: 2722px) 100vw, 2722px\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 2722px; --smush-placeholder-aspect-ratio: 2722\/2007;\" \/><\/figure>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-vertically-aligned-center is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:66.66%\">\n<div class=\"wp-block-group is-nowrap is-layout-flex wp-container-core-group-is-layout-ad2f72ca wp-block-group-is-layout-flex\">\n<h3 class=\"wp-block-heading\"><strong>Private and private defects<\/strong><\/h3>\n<\/div>\n\n\n\n<p>Between 2020 and 2025, volunteers found 102 incidents of private defects and 269 incidents of public defects.<\/p>\n\n\n\n<p>Private defects encompass any defect except those not defined elsewhere. This designation covers a diverse array of uncommon and potentially unique defects, with one similarity being that the issue relates to the customer&#8217;s private drainage system.<\/p>\n\n\n\n<p>Public defects are the responsibility of Thames Water to rectify, as it has occurred to the part of the drainage system that Thames Water is responsible for.<\/p>\n\n\n\n<p>For both categories, as each incident is unique, the response is tailored to the specific situation.<\/p>\n\n\n\n<p><\/p>\n<\/div>\n<\/div>\n<\/div><\/div>\n\n\n\n<div class=\"wp-block-group is-layout-constrained wp-block-group-is-layout-constrained\"><\/div>\n\n\n\n<div class=\"wp-block-cover is-light add-cover-padding\" style=\"min-height:420px;aspect-ratio:unset;\"><img decoding=\"async\" class=\"wp-block-cover__image-background wp-image-99 lazyload\" alt=\"\" data-src=\"https:\/\/castco.org\/wp-content\/uploads\/2024\/08\/section-bkground-2.png\" style=\"--smush-placeholder-width: 1920px; --smush-placeholder-aspect-ratio: 1920\/999;object-position:50% 100%\" data-object-fit=\"cover\" data-object-position=\"50% 100%\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" \/><span aria-hidden=\"true\" class=\"wp-block-cover__background has-background-dim\" style=\"background-color:#fafef1\"><\/span><div class=\"wp-block-cover__inner-container is-layout-constrained wp-block-cover-is-layout-constrained\">\n<div style=\"height:20px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<div class=\"wp-block-group is-layout-constrained wp-block-group-is-layout-constrained\">\n<div class=\"wp-block-columns are-vertically-aligned-center is-layout-flex wp-container-core-columns-is-layout-9d6595d7 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-vertically-aligned-center is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:33.33%\">\n<figure class=\"wp-block-image alignleft size-full\"><img decoding=\"async\" width=\"800\" height=\"800\" data-src=\"https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/CASTCOgif.gif\" alt=\"\" class=\"wp-image-3604 lazyload\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 800px; --smush-placeholder-aspect-ratio: 800\/800;\" \/><\/figure>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-vertically-aligned-center is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:66.66%\">\n<h2 class=\"wp-block-heading\">A multi-faceted purpose, with diverse data sources<\/h2>\n\n\n\n<p>The Outfall Safari Programme moves into all aspects of <a href=\"https:\/\/castco.org\/knowledge-base\/monitoring-purpose\/\" target=\"_blank\" rel=\"noreferrer noopener\">monitoring purpose<\/a>, with community engagement at the heart of it. By moving through to investigation and resolving issues, Outfall Safari provides mechanisms to allow the community to improve rivers meaningfully and provide an interface between those with the means to do so. <\/p>\n\n\n\n<p>This scheme also demonstrates CaSTCo&#8217;s &#8216;Weight of Evidence&#8217; approach, combining data from community surveys with detailed surveys and data from both the EA and the water company. It&#8217;s blending these different data sources together that makes this program so successful!<\/p>\n\n\n\n<p>As part of the CaSTCo project, Outfall Safari also ran three &#8220;Train The Trainer&#8221; sessions between December 2024 and January 2025 in the Anglian, Teme and Mersey demos, expanding the method into other regions. Plus, through the r<span style=\"box-sizing: border-box; margin: 0px; padding: 0px;\">ollout of the&nbsp;<a href=\"https:\/\/cartographer.io\/\" target=\"_blank\">Cartographer app and database<\/a>&nbsp;for the collection of Outfall Safari data across the UK, and updated guidance (supported by ten CaSTCo partner organisations), integrating in user feedback, has built a robust toolset for the entire country.<\/span><\/p>\n\n\n\n<p><\/p>\n<\/div>\n<\/div>\n\n\n\n<p><\/p>\n<\/div>\n<\/div><\/div>\n\n\n\n<div class=\"wp-block-columns block is-layout-flex wp-container-core-columns-is-layout-9d6595d7 wp-block-columns-is-layout-flex\"><\/div>\n\n\n\n<div class=\"wp-block-group is-layout-constrained wp-block-group-is-layout-constrained\">\n<div class=\"wp-block-columns are-vertically-aligned-center is-layout-flex wp-container-core-columns-is-layout-9d6595d7 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-vertically-aligned-center is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:33.33%\">\n<figure class=\"wp-block-image size-full is-style-circle-frame\"><img decoding=\"async\" width=\"440\" height=\"592\" data-src=\"https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Picture6-1.jpg\" alt=\"\" class=\"wp-image-3462 lazyload\" data-srcset=\"https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Picture6-1.jpg 440w, https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Picture6-1-37x50.jpg 37w\" data-sizes=\"(max-width: 440px) 100vw, 440px\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 440px; --smush-placeholder-aspect-ratio: 440\/592;\" \/><\/figure>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-vertically-aligned-center is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:66.66%\">\n<h2 class=\"wp-block-heading\"><strong>Demonstrating CaSTCo principles<\/strong><\/h2>\n\n\n\n<p><strong>Collaboration<\/strong><br>The Outfall Safari was developed in collaboration with a range of organisations in London, including local communities, organisations, NGOs, water companies, and regulators to collect data on polluted surface water outfalls (PSWOs).<\/p>\n\n\n\n<p><strong>Open<\/strong><br>Our data is available upon request and is shared annually with all stakeholders, local policymakers, and citizen scientists. Further prototypes to share data openly and allow data to be easily combined with other datasets for bigger impact are underway.<\/p>\n\n\n\n<p><strong>Impactful<\/strong><br>Since 2016, the Outfall Safari in London has conducted 4,465 outfall assessments and identified 638 polluting outfalls, engaging 490 community members across Greater London. The data is shared across all stakeholders and has been fed into the Greater London Authorities <a href=\"https:\/\/apps.london.gov.uk\/river-health\/\" target=\"_blank\" rel=\"noreferrer noopener\">River Health Map<\/a> and will be used as part of the evidence base to inform the Mayor of London&#8217;s plan for <a href=\"https:\/\/www.london.gov.uk\/Mayor%20brings%20together%20landmark%20coalition%20to%20deliver%20major%20new%20improvements%20to%20London%E2%80%99s%20rivers\" target=\"_blank\" rel=\"noreferrer noopener\">clean and healthy waterways<\/a>.<\/p>\n\n\n\n<p>Outfall Safari has also laid the foundations for building similar programmes in other cities and regions!<\/p>\n\n\n\n<div class=\"wp-block-buttons is-content-justification-left is-layout-flex wp-container-core-buttons-is-layout-fdcfc74e wp-block-buttons-is-layout-flex\">\n<div class=\"wp-block-button\"><a class=\"wp-block-button__link wp-element-button\" href=\"https:\/\/www.zsl.org\/what-we-do\/projects\/londons-rivers\">Learn more &amp; get involved<\/a><\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n<div class=\"wp-block-group is-layout-constrained wp-block-group-is-layout-constrained\">\n<div class=\"wp-block-group is-layout-constrained wp-block-group-is-layout-constrained\"><\/div>\n<\/div>\n\n\n\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-9d6595d7 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<div class=\"wp-block-cover\"><img decoding=\"async\" width=\"1000\" height=\"584\" class=\"wp-block-cover__image-background wp-image-3493 size-full lazyload\" alt=\"\" data-src=\"https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Screen-Shot-2025-05-20-at-11.06.34-AM.png\" data-object-fit=\"cover\" data-srcset=\"https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Screen-Shot-2025-05-20-at-11.06.34-AM.png 1000w, https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Screen-Shot-2025-05-20-at-11.06.34-AM-640x374.png 640w, https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Screen-Shot-2025-05-20-at-11.06.34-AM-768x449.png 768w, https:\/\/castco.org\/wp-content\/uploads\/2025\/05\/Screen-Shot-2025-05-20-at-11.06.34-AM-50x29.png 50w\" data-sizes=\"(max-width: 1000px) 100vw, 1000px\" src=\"data:image\/svg+xml;base64,PHN2ZyB3aWR0aD0iMSIgaGVpZ2h0PSIxIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciPjwvc3ZnPg==\" style=\"--smush-placeholder-width: 1000px; --smush-placeholder-aspect-ratio: 1000\/584;\" \/><span aria-hidden=\"true\" class=\"wp-block-cover__background has-background-dim-0 has-background-dim\" style=\"background-color:#707664\"><\/span><div class=\"wp-block-cover__inner-container is-layout-flow wp-block-cover-is-layout-flow\">\n<p><\/p>\n<\/div><\/div>\n<\/div>\n\n\n\n<div class=\"wp-block-column has-bg-color has-secondary-background-color has-text-color has-background has-link-color wp-elements-4d040a0241bb643e15f8ae16a319d62e is-layout-flow wp-block-column-is-layout-flow\">\n<blockquote class=\"wp-block-quote block is-layout-flow wp-block-quote-is-layout-flow\">\n<p><\/p>\n\n\n\n<p>Being part of CaSTCo has shown me the power of collaboration. Training others to run their own Outfall Safaris helped spark important conversations between NGOs and water companies, and the shared learning across regions has been invaluable. I\u2019ve seen how working together can break down barriers, reduce duplication, and build towards a future where every UK city is monitoring PSWOs and contributing to a national dataset.<\/p>\n\n\n\n<p><strong><strong>Elizabeth Witcombe<\/strong><\/strong>, Estuaries and Wetlands Project Officer at ZSL<\/p>\n<\/blockquote>\n<\/div>\n<\/div>\n\n\n\n<div class=\"wp-block-group is-style-no-margin has-bg-alt-2-background-color has-background is-layout-constrained wp-block-group-is-layout-constrained\">\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-9d6595d7 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:66.66%\">\n<h2 class=\"wp-block-heading has-text-align-left is-style-no-margin-bottom\">Supporting <strong>material<\/strong><\/h2>\n\n\n\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-9d6595d7 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<div class=\"wp-block-group is-nowrap is-layout-flex wp-container-core-group-is-layout-ad2f72ca wp-block-group-is-layout-flex\">\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><tbody><tr><td><a href=\"https:\/\/castco.org\/knowledge-base\/method-audit-outfall-safari\/\" target=\"_blank\" rel=\"noreferrer noopener\">CaSTCo Method Audit: Outfall Safari<\/a><\/td><\/tr><tr><td><a href=\"https:\/\/catchmentbasedapproach.org\/learn\/outfall-safari-guide\/\" target=\"_blank\" rel=\"noreferrer noopener\">CABA: Outfall Safari Guide and Resource Pack<\/a><\/td><\/tr><tr><td><a href=\"https:\/\/www.zsl.org\/what-we-do\/projects\/londons-rivers\" target=\"_blank\" rel=\"noreferrer noopener\">ZSL: London rivers case study<\/a><\/td><\/tr><tr><td><a href=\"https:\/\/catchmentbasedapproach.org\/wp-content\/uploads\/2019\/02\/ZSL_TheRiversTrust_Outfall_Safari_Guide_Final.pdf?_gl=1*mbkj1i*_up*MQ..*_ga*MTgyNDIyMzE2Ny4xNzQ3NzUzMjMz*_ga_B1593W7WQH*czE3NDc3NTMyMzIkbzEkZzAkdDE3NDc3NTMyMzIkajAkbDAkaDAkZEJxM0hUM203X1ZLRlJWa2FCNjlsbUtVdTNhQkl5Z2FwNnc.*_ga_NY80EKWNL4*czE3NDc3NTMyMzMkbzEkZzAkdDE3NDc3NTMyMzMkajAkbDAkaDAkZGpZZFJWTWtZbVFZUy02dGJ6M194NHBoNU1CbU4wOGpjU2c.\">ZSL: Tackling pollution in urban rivers: a guide to running Outfall Safari<\/a><\/td><\/tr><tr><td><a href=\"https:\/\/www.thameswater.co.uk\/news\/national-drainage-misconnection-day-2022\">Thames Water: Thames Water partners with ZSL <\/a><\/td><\/tr><tr><td><a href=\"https:\/\/www.thameswater.co.uk\/about-us\/regulation\/our-five-year-plan\">Thames Water: Thames Water five year plan (Amp7)<\/a><\/td><\/tr><tr><td><a href=\"https:\/\/www.london.gov.uk\/Mayor%20brings%20together%20landmark%20coalition%20to%20deliver%20major%20new%20improvements%20to%20London%E2%80%99s%20rivers\">London Government: Mayor of London&#8217;s plan for clean and healthy waterways<\/a><\/td><\/tr><\/tbody><\/table><\/figure>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n<p><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Outfall Safaris help communities identify hidden pollution from surface water outfalls, providing data that supports clean-up efforts by Thames Water and environmental partners.<\/p>\n","protected":false},"featured_media":3348,"template":"","case_study_tag":[52],"class_list":["post-3423","case-study","type-case-study","status-publish","has-post-thumbnail","hentry","case_study_tag-pollution"],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.5 - 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