SWIM in HoTWater

Royal Mail delivered the R-Cards and the incubator today so I will be looking for the best way to test one of them.  I suspect this will be side by side with the HoTWater team in Henley so that I have some sort of a reference. 

 The following photo is of a R-Card of unknown origin. It is included for demonstration purposes only. Each blue dot indicates the presence of E.coli in a 1 ml sample      row 1 = 1      row 2 = 12      row 3 = 49      row 4 = 43      row 5 = 45      row 6 = 13 total = 163 Because the accepted unit of measurement is colony forming units of E.coli per 100 ml sample, we multiply 163 x 100 giving 16300 cfu/100ml  In practice we will be examining 3 cards for each test and recording the mean/average of the 3 cards. Because 16300 is greater than 900 the Environment Agency would classify this sample as "poor", and advise against swimming. Me too ( I hope samples from the Thames are not a polluted as this ).

  SWIM refers to Shiplake and Wargrave Indicative Monitoring (of E.coli in the river) which is associated the HoTWater group . It’s just a light hearted name for a dirty topic. Hopefully, one day, we will be able to SWIM in clean water.

 

In 2025 I worked with the HoTWater group in Henley monitoring E. coli levels in the Thames, with results published online and via the HoTWater app. In 2026, Irene and I plan to extend weekly testing (May–October) to the Wargrave & Shiplake stretch. We’ll cover setup costs and the first 10 tests. Each additional test costs about  £11 , and we’d welcome: • Occasional volunteers to help test • Contributions to pay for 1 or more tests Interested? Please email: swimtesting@gmail.com John & Irene Crawford Shiplake Now fully funded for 2026