Bacteria Water Test Results Guide

What this test measures

Test strips cannot detect bacteria, so your kit includes a separate coliform bacteria test. Coliforms are a family of bacteria that live in soil, on plants and in the gut of animals. Most are harmless in themselves, but finding them in drinking water shows that something from the environment is getting in, which is why UK regulations do not allow any in tap water.

The UK standard

UK drinking water regulations require no coliform bacteria, E. coli or enterococci in any 100 ml sample. Mains supplies are disinfected and monitored constantly; private supplies (wells, boreholes and springs) are the owner's responsibility, which is why routine screening earns its keep.

Reading your test

Add 2 ml of your sample to the pouch, seal it and lay it flat. Read it after 48 hours at room temperature, or 24 hours at 37°C. Purple, or no colour change, means no coliform bacteria were detected. Yellow means coliform bacteria are likely present. The result is a screening result, not a certified laboratory count.

What to do next

• A positive result is a prompt to confirm, not a panic. Re-test with a fresh sample taken straight from the tap, without touching the inside of the pouch.
• While you investigate a positive result, boil water for drinking, cooking and teeth-brushing, or use bottled water.
• On a mains supply, report it to your water supplier; they investigate quality concerns free of charge.
• On a private supply, contact your council's environmental health team, and check the wellhead or spring chamber for surface water getting in. If you have a UV unit, check the lamp and pre-filter.
• We can arrange a UKAS-accredited laboratory test to confirm the result: email info@waterkit.co.uk or use the lab test button on your report.
• Repeat the test routinely on a private supply, and after heavy rain, flooding or any work on the source.