Water quality sensors to alert wild swimmers to real-time pollution risk

Real-time water quality monitors are being installed at wild swimming spots and beaches across southern England to help people assess their immediate risk of illness from polluted water.

- Linda Geddes

Wessex Water is installing sensors at three freshwater sites in Dorset, Somerset and Hampshire, plus two coastal sites in Bournemouth, after a successful pilot at Warleigh Weir near Bath. Here, the artificial intelligencebased system correctly predicted when bacteria in the water were high 87% of the time.

Southern Water is testing a different system at Tankerton in Kent and Langstone Harbour in Hampshire, with a further sensor expected soon at nearby Hayling Island.

Although water companies and regulators now test river water for markers of pollution that harm wildlife, there is no requirement to test for faecal bacteria such as E coli and intestinal enterococci unless the site is a designated bathing water.

Even here, water samples must be sent to a lab for analysis, and the results are not published for a week or so afterwards, with final classification each November. This makes it difficult to assess the immediate risk from sewage or agricultural runoff.

"People may be swimming at a location all year, and it is only when the final classification is published that they realise what the quality has been," said Ruth Barden, the director of environmental solutions at Wessex Water.