Help us map the UK's tap water quality


Help us map the UK's tap water quality


Practical Fishkeeping is planning a nationwide project to map the chemistry and quality of the UK's tapwater so fishkeepers have a better understanding of how it needs to be treated.

Across the country, tapwater differs widely in both pH and hardness, as well as the presence of pollutants, such as nitrate and phosphate, and the way in which it is disinfected.

A growing number of water authorities, including as Thames, Welsh Water, Scottish Water and parts of Anglian Water, have now switched from dosing their water supplies with chlorine to adding a different disinfectant called chloramine.

Although this is better for human health, it's considerably more dangerous to fish and can't be removed through aeration or the use of standard dechlorinators, as chlorine can.

Chloramine use could be much more widespread than many people realise, and many people may not be treating their water effectively, leaving fish exposed to potentially harmful levels of chlorine.

Because chloramine is produced by adding liquid ammonia to the chlorinated water supply, the knock-on effect is that our tapwater is now much more likely to contain higher levels of ammonia and nitrite than it has done in the past.

This shift in disinfecting technology has also seen the standards for the presence of nitrite and ammonia in tapwater lowered, so although water meets Drinking Water Inspectorate standards it might not be ideal for keeping fish in.

How you can helpWe're asking readers to contact their local water authority to obtain a copy of a very specific type of report, known as a Schedule Four Drinking Water Quality Report. This should not be confused with the company's annual report, which is freely available from the Drinking Water Inspectorate.

View the UK's water quality and chemistry on an interactive map.

The Schedule Four report we're after is specific to the zone you live in, so you will probably need to state your postcode when requesting it.

This detailed document is available free from either your local water authority website, or by calling the telephone number that appears on your water bill.

The Drinking Water Quality Report includes test results and provides values for virtually every chemical parameter you can think of, from the pH to the amount of phosphate and chlorine present. If you send a copy of your postcode-specific Report to us, we'll extract the data and add it to our online interactive UK Tapwater Quality Map.

Practical Fishkeeping Technical Writer, Jeremy Gay, who supplied the first report from his local Northampton West zone of Anglian Water's catchment said: "It's opened my eyes. I had no idea there was chloramine in my tapwater.

"I worked in the aquatic trade in Northampton for many years and we were not informed that chloramine was present in the supply, so we weren't removing it properly."

Get the right reportImportantly, you need to ensure that you request a report for your specific supply zone, as the water supplied by an authority can differ across a region, particularly if you live in a very large county, such as North Yorkshire in which the water varies greatly in chemistry.

All water authorities produce annual reports on their water quality which describe how well they did at meeting the Drinking Water Inspectorate standards. Unfortunately, these lack the specific technical information we need, so please make sure you ask or search for the correct type of report.

Confusingly, different water authorities may use different terminology for Drinking Water Quality Reports (sometimes known as DWRs). You may see need to ask for a Schedule 4 report or PWZ report.

When you've got your zone specific report, please either email the PDF document to [email protected] or send it by post to: UK Tap Water Quality Map, Practical Fishkeeping, Bretton Court, Bretton, Peterborough, PE3 8DZ.

We will send a free gift to the first report we receive from each water authority, and you'll get an acknowledgement on the map.


Thank you to all of the readers who have sent in water reports. We now have all reports for the United Utilities area, but we don't have very many at all for the south west of England.