Signs of sewage

How to tell if sewage pollution is affecting your local swim spot

Even without formal water quality testing in place, there are some ways to tell if your swim spot is being affected by sewage.

  • Sight & smell check
    Are there visible signs of untreated sewage pollution? This could be “rag” (sanitary items, nappies), a bad odour or grey “milky” water. Sewage fungus is another sign.
  • Sewage spill history
    Check The Rivers Trust Sewage Map for information on when untreated sewage pollution entered your waterway in the previous year.
  • Sick after swimming
    Has anyone been sick after swimming in your stretch of river or lake?
  • Citizen Science
    Carry out Citizen Science water quality testing – SAS and your local member Rivers Trust will be able to help signpost you to funding and water quality testing programmes.

Any evidence you have on the state of your river or lake will help in your campaign in applying for bathing water designation. Ensuring your community are informed on

the issues will help in getting them on board.


However, as people are likely to be using the waterway to swim, paddle, fish and kayak it is important to strike a balance on how you communicate the water quality issues.

There are many benefits to being in blue spaces, and it would be a shame to put people off entirely. Emphasise that it is down to individuals to assess the risk of using the river or lake themselves. Good general advice is to avoid entering the water until 48 hours after heavy rainfall. This is likely when sewage overflows will have discharged untreated sewage.

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