HoTWater

About the HoTWater App

The HoTWater app aims to provide river users with information on E. coli bacteria levels in river water. These bacteria levels are an indicator of water quality and potential health risks.

Unlike designated bathing sites, most stretches of our rivers do not have designated bathing status, meaning environmental agencies do not routinely monitor the water quality in a river.

In designated bathing areas, water quality is monitored regularly during the bathing season to help the public assess the risks of entering the water. These tests measure bacteria including E.coli, with results reported in colony-forming units per 100ml ( cfu/100ml ).

Environmental agencies classify water quality into the following categories:
• Excellent – EC: ≤500 cfu/100ml
• Sufficient – EC: ≤900 cfu/100ml
• Poor – Worse than Sufficient

If water quality is rated Poor, authorities advise against swimming.


How the HoTWater App Fills the Gap

Since no official monitoring exists for most stretches of our rivers, local volunteers test river water in their geographical areas (In Henley-on-Thames, water samples are currently taken using a Fluidion Alert 1 analyser to assess water samples at four sites: two on Tuesdays and two on Thursdays. Test results are typically published the following day, once analysis is complete)

The HoTWater app may also display results provided by other local groups operating in their own local areas. All groups contributing data, including HoTWater, work to best endeavours, and results are shared in good faith for the benefit of all river users.

While we apply DEFRA classifications to our results for reference, it’s important to note that official classifications are based on seasonal data, not single samples. DEFRA classifications also involve tests for Intestinal Enterococci. In line with DEFRA, we do not test silt from the riverbed.

It should also be noted that the DEFRA classifications refer to results from laboratory tests that follow DEFRA standards, whereas the results displayed in the HoTWater app come from a Fluidion ALERT 1 analyser, which provides for more rapid results. However, the Fluidion ALERT 1 results are often higher than the DEFRA results because they can also detect particle-associated E.coli that DEFRA methods may miss.

Why This Matters

Our rivers often include output from numerous water company outflow pipes, and run through residential, commercial and agricultural areas
Many individuals, clubs, and organisations are concerned about water quality and the lack of up-to-date official data to guide their activities on the river.

The HoTWater app aims to bridge this information gap, helping river users make more informed decisions about their water-based activities.

Certification: The HoTWater group is certified under the Fluidion Water Safety Excellence Program