Water Quality Live

No. The alerts and any related data do not constitute a definitive assessment of water quality at a given time. It is the responsibility of the user to consider whether the water is safe to enter.

Water quality is one of several factors that users should consider when entering water for recreational purposes; others include currents, water temperature, wave height and surge, wind speed and direction.

While the aim is to ensure such information is accurate, it only provides a guide to the likely water quality and the processes used are subject to a margin of error. There are no guarantees, conditions or warranties that the information is current, accurate or complete.

Wild swimming, as with any recreational use of outdoor waters, has its dangers – any participation in such activity is entirely at your own risk as is any use of this app and/or the information that it provides.

Water quality alerts are currently only provided at Warleigh Weir, but in-river sensors are being installed and AI is being trained to provide them at:

• Fordingbridge
• Farleigh Hungerford
• Poole Park Lake.

Bathing water quality is measured by looking at the levels of faecal indicator bacteria present in them. Traditionally, samples are collected by hand and taken to a laboratory where the bacteria are grown in incubators on petri dishes and analysed under controlled conditions. This takes around three days, which is far too long to inform water users of the level of risk they may be encountering if they enter the water.

Since no technology can continuously measure the concentration of these bacteria, this solution has been developed to utilise readily available sensors that provide robust real-time measurements of other water quality indicators, including temperature, pH, conductivity, dissolved oxygen and river flow.

The information from the sensors and lab samples is used to train algorithms to predict the bacteria levels at bathing locations all year round.

Under the current Bathing Water Regulations, lab samples are taken approximately weekly. The bathing water quality is classified as excellent, good, sufficient or poor based on 95th and 90th percentiles of the concentration of E. coli and Intestinal Enterococci in the samples over a four-year rolling period.

The bacteria are indicator organisms reflecting the likelihood of pathogenic organisms that can cause illnesses if consumed, so their presence means there is a potential risk to bathers' health. The greater the concentration, the greater the health risk if ingested.

There are currently no government guidelines for real-time bathing water quality standards, so informed decisions are made based on existing bathing water levels to set alerts for when E. coli and Intestinal Enterococci are predicted to exceed certain levels.

Swim alerts are set for when E. coli levels are predicted to exceed 900 colony forming units per 100 ml, and Intestinal Enterococci levels are predicted to exceed 300 colony forming units per 100 ml.

It can take anywhere between 12 to 24 months to train the algorithms used to predict bacteria levels. The time it takes depends on the amount of data necessary and the complexity of the catchment area.

This is the process:

1. Install sensors at a bathing location.
2. Take routine lab samples.
3. Review flow, rainfall and asset information.
4. Train algorithms to predict bacteria levels.
5. Ensure predictions are sufficiently accurate using ongoing lab sampling.
6. Provide alerts to local users.

Flow rate and rainfall levels are measured using the Environment Agency's river flow and rain gauge stations. We then share this information under the Open Government Licence.

Alerts are not provided for flow rate or rainfall. It is your responsibility to decide if the water is safe to enter.