Should you take the plunge? How to tell how clean the sea is

By

South West environment and tourism correspondent

Bathing water quality can be affected by several factors including sewage spills, heavy rain, agricultural run-off, urban pollution and wildlife.

All of these factors can affect levels of bacteria in the water and the potential risk to swimmers.

A sewage spill does not automatically mean water quality has been affected and the absence of an alert does not guarantee clean water.

More than a third of England's designated bathing waters are in Devon and Cornwall.

This includes popular beaches such as Sennen Cove and Porthcurno on Cornwall's dramatic west coast, to Fistral on the county's north coast, Bigbury-on-Sea in south Devon and surfing hotspot Croyde Bay in north Devon.

The Environment Agency, the regulator which monitors water quality at bathing waters, rates bathing waters from "excellent" to "poor" based on bacteria found in water samples collected over a rolling four-year period.

Samples taken from the water are tested in a lab for elevated levels of E. Coli and intestinal enterococci.

The bacteria can be found in sewage and other waste and can lead to sickness, stomach cramps, vomiting, and diarrhea.

The Environment Agency says the testing regime helps "build a detailed, accurate long-term profile of a site to inform the public's decision of where to visit".

However, the testing only takes place during the bathing water season, which runs from 15 May until the end of September, and only at sites that have been already designated as bathing waters.

It does not give information about conditions on a particular day.

Critics such as Cornwall-based campaign group Surfers Against Sewage argue the system is "not fit for purpose" as people use beaches all year round.

The ratings are available on the Swimfo, external website.

Surfers Against Sewage (SAS) has developed their own app, external developed an app to provide alerts when bathing water quality could be affected by pollution, including sewage spills.

It says the information comes from various sources including voluntarily data from water companies in England and Wales, from sensors that monitor when a Combined Sewer Overflow operates.

The alert stays live for 48 hours post-discharge.

It says UK water companies keep pollution alerts active for varying periods so "for the safety of water users, SAS follows the precautionary approach to keep the current alerting system in place at 48 hours".

The app also includes features such as tide information, health reporting and a live map showing active overflow discharges.

Water companies also provide information on when bathing water quality could be affected by sewage spills.

South West Water has WaterFit Live, external, which the company says helps "people make informed decisions before they swim".

An alert is displayed for 12hours and 30 minutes after a spill concludes.

A separate storm overflow map shows storm overflows in "near real time", with overflows remaining visible for 24 hours after they end.

The utility company says its storm overflow map "simply reports whether an overflow is operating and does not assess bathing water quality risk, which is assessed separately at beach level using the methodology published on the WaterFit Live website".

The Blue Flag scheme , externalassesses beaches against strict criteria covering water quality, environmental management, safety, accessibility and environmental education.

It is operated globally by the Foundation for Environmental Education but managed in England by Keep Britain Tidy.

Some of the Blue Flag beaches include Carbis Bay, Summerleaze and Polzeath in Cornwall, as well as Exmouth, Sidmouth and Blackpool Sands in Devon.

To get a Blue Flag, a beach must have "excellent" bathing water quality, as rated by the Environment Agency.

Unrelated to the Blue Flag scheme, red flags can sometimes be flown at beaches and bathing waters following a short-term pollution incident.

They warn people not to swim until water quality is deemed safe again.

A growing number of community groups across the South West are testing pollution levels at beaches, rivers and waterways.

Friends of the River Teign, external is one such group uses volunteers equipped with real-time testing kits to provide "more frequent, more localised water quality information across River Teign estuary and surrounding coastal waters".

Carolyn Sargentson said the testing would provide "a publicly accessible data set" as part of their campaign for "cleaner water".

A spokesperson for the Department for Environment, Food and Rural Affairs said the government had "taken swift action against water companies who are failing to perform" which included a ban on unfair bonuses for water bosses and making it unlawful to cover up illegal spills.

They said the government was also bringing in a new regulator, no-notice inspections and "MOT-style" checks on water firms.

Bathing water regulations were being upgraded "for the first time in over a decade", they added.

Follow BBC Devon on X, external, Facebook, external and Instagram, external. Send your story ideas to spotlight@bbc.co.uk, external.