What is chloramination?
Chloramination is an alternative means of providing a residual disinfectant that is used in some parts of Scotland and elsewhere. A small quantity of ammonia is added to chlorine after the disinfection process to form a long-lasting disinfectant called monochloramine. It has been in common use within the water industry for many years.
Why do water companies use chloramination?
The main advantage of chloramination is that it persists longer through the distribution pipework, keeping the water safe from bacteria and other bugs.
The chlorine taste of water that is chloraminated is usually less noticeable to consumers than chlorine alone.
Chloramination also has the advantage that it reduces the formation of some regulated by-products (trihalomethanes or THMs ) that can form when chlorine is added to water.
Is chloramination safe?
Yes. Chloramination is perfectly safe at the levels used in drinking water in Scotland. It has been used for many years in parts of Scotland such as Edinburgh, Aberdeen and Inverness with no issues. The World Health Organisation provide the authoritative guidance on safe levels of substances in drinking water. You can read this detailed guidance at Guidelines for drinking-water quality: Fourth edition incorporating the first and second addenda (who.int) .
I've heard that chloraminated water can harm fish. Is that true?
Fishkeepers need to de-chlorinate any tap water that they use for fish. Chloraminated water needs a slightly different (but readily available) product to de-chorinate the water, therefore they need to be aware how their water is disinfected. Any reputable fishkeeping shop should be able to advise.
There is no reason why chloraminated tap water should be harmful to fish in the aquatic environment. The tiny amount that is used in the water supply dissappears completely by the time it has passed through the sewerage system.
What is DWQR's view of chloramination?
Chloramination is a valid and safe treatment process that has been used for many years in the water industry across the UK. It is therefore available for Scottish Water to use, should they choose to do so. As with any treatment process, Scottish Water is expected to control it very carefully and fully address any concerns that consumers may have.