Water Healer Magazine (Korea)

Chlorine or Chloramine in Your Shower Water? How to Check

Look up your water supplier's report for 'chlorine' or 'chloramine', read the mg/L figure, and see what public bodies say about showers, fish tanks and dialysis.

8 min readWater Healer (Korea)

Also in: シャワーの水は塩素かクロラミンか？ 水質報告書での調べ方

Short answer: Your water supplier publishes which disinfectant it uses, usually in a water quality report or on its website, so you can look it up instead of guessing. The World Health Organization (WHO) gives 5 mg/L as the guideline value for free chlorine in drinking water, and the Drinking Water Inspectorate (DWI), the regulator for England and Wales, says levels there are well below it. Health Canada expects exposure to chloramines through showering or bathing to be negligible, while fish keepers and home dialysis users need to know which one they have.

You notice a faint swimming-pool smell in the shower steam, or a neighbour with a fish tank asks what is in the tap water. Behind both questions is the same fact: water is disinfected so that it stays safe all the way from the treatment works to your tap. The disinfectant is usually chlorine or chloramine, and for some households the difference matters.

Why is there a disinfectant in tap water?

The DWI explains it this way: water is safe when it leaves the treatment works, and the trace of chlorine is there only to preserve its quality as it passes through the miles of pipes that carry it to homes and workplaces. In England and Wales it is a regulatory requirement for companies to disinfect their water and hold a residual chlorine concentration within the network.

What is the difference between chlorine and chloramine?

Health Canada defines chloramines as oxidising compounds containing one or more chlorine atoms attached to a nitrogen atom. It adds that monochloramine is more stable than free chlorine and so keeps disinfecting for longer, which is why it is commonly used in the distribution system as a secondary disinfectant. Chloramines have also been used in distribution systems to help reduce the formation of common disinfection by-products.

Which one a supplier uses varies by place. Health Canada says the majority of drinking water treatment plants in Canada use some form of chlorine. Water Corporation in Western Australia says it adds chlorine to all of its supply schemes. Sydney Water says it adds different chemicals to drinking water, including chlorine and ammonia, and its water analysis tool lets you choose between free chlorine, total chlorine and monochloramine. So one supplier can report several disinfectant measures.

How do I check what my supplier uses?

  1. Find your supplier. Check your water bill, or ask your landlord or building manager.
  2. Open its water quality page or annual report. Many suppliers publish an annual drinking water quality report. Water Corporation, for example, publishes a drinking water quality annual report and keeps earlier years' reports on the same page, and Sydney Water offers a tool where you enter your address to see the water analysis for your area. The DWI says water companies in England and Wales will provide a free water quality report on request, showing the maximum and minimum level of residual chlorine in your local supply.
  3. Search the report. Look for "chlorine", "chloramine", "monochloramine" and "total chlorine".
  4. Ask if it is unclear. If the report does not name the disinfectant, contact the supplier and ask directly. The DWI notes that higher levels are sometimes needed during maintenance of the pipe network, which can explain an occasional taste or smell of chlorine.

How do I read the numbers?

Levels are given in milligrams per litre (mg/L or mg/l). Reference points from public bodies:

SourceWhat it says
WHOThe guideline value for free chlorine in drinking water is 5 mg/L
DWI (England and Wales)Water companies typically keep residual disinfectant, as free or combined chlorine, to 0.5 mg/l or less, and most aim to stay below 1 mg/l
Health CanadaFree chlorine in most Canadian distribution systems ranges from 0.04 to 2.0 mg/L, and most Canadian supplies that use chloramines keep the residual below 4 mg/L
Sydney WaterCompares chlorine at your tap with the Australian Drinking Water Guidelines limit of 5 milligrams per litre

Taste is a different matter from safety. WHO notes that most individuals can taste chlorine or its by-products, such as chloramines, at concentrations below 5 mg/litre, and some at levels as low as 0.3 mg/litre. Health Canada says sensitive individuals may detect chlorine at levels as low as 0.6 mg/L. That helps explain why two people in the same house can disagree about whether the water smells of chlorine.

Minerals are a separate question; see hard water and hair.

What do public bodies say about showering?

Only one source quoted here addresses showering.

Health Canada's technical document on chloramines states that exposure to chloramines via inhalation and skin contact during showering or bathing is expected to be negligible. The other pages quoted here deal with drinking water and do not comment on showering.

The DWI says that at the very low levels used in drinking water, chlorine is a proven public health measure, and that some people find it a concern because they are very sensitive to its taste and smell. If you have a health concern about your own skin or breathing, ask a doctor, because a water report cannot answer it.

Do fish tanks and dialysis need extra care?

Yes. The sources single out both.

Fish and aquariums. Sydney Water says that the chemicals added to drinking water, including chlorine and ammonia, are present at low and safe concentrations but may affect fish or other creatures in a tank, aquarium or pond. Its fish fact sheet adds that fish gills allow easy absorption of chemicals, so chlorine should be removed before water goes into an aquarium or pond. Health Canada says aquarium owners must ensure the use of proper aeration or chlorine/chloramine quenching, which means neutralising the disinfectant before the water goes into the tank.

Home dialysis. Health Canada says dialysis treatment providers at every level, including those for independent or home dialysis, should be notified when the water is chloraminated. If someone in your household has home dialysis, tell the dialysis unit which disinfectant your supplier uses and follow its instructions on preparing the water.

Does leaving water to stand remove the smell?

For chlorine, often yes. The DWI suggests putting a jug of tap water in the fridge for a short period to reduce the chlorine smell or taste, and to throw away unused water after 24 hours and clean the jug regularly. Sydney Water says the smell and taste of chlorine should disappear if you let water stand in a jug for about an hour or keep it in the fridge. For aquariums, it says that to dechlorinate water it is usually enough to leave it in an open container for 48 hours, and in the same paragraph it adds that you can also use an aquarium water conditioner to remove chlorine and chloramine.

All of these standing and chilling tips are worded for chlorine. None of the sources quoted here describes standing or chilling as a way to remove chloramine. Health Canada describes monochloramine as more stable and longer lasting than free chlorine, and it notes that for consumers who find the taste of chloramines objectionable, there are residential drinking water treatment devices that can decrease chloramine concentrations. So do not assume that a jug on the counter removes chloramine. Ask your supplier what works for your water; for a fish tank, an aquarium shop can also advise.

What should I do next?

Note the disinfectant and the mg/L figure from your supplier's report. If you keep fish or use home dialysis, act on the advice above first. If you are considering a shower filter, check what the maker has tested it against and compare that with the disinfectant your supplier reports. For a related household task, see how to clean limescale from your showerhead.

FAQ

How can I tell if my water has chlorine or chloramine?

Check your supplier's water quality report or website and search for "chlorine", "chloramine", "monochloramine" and "total chlorine". If the disinfectant is not named, ask the supplier. The DWI notes that companies in England and Wales provide a free water quality report on request.

Is chloramine safe to shower in?

Health Canada's technical document on chloramines states that exposure through inhalation and skin contact during showering or bathing is expected to be negligible. For personal health questions, speak to a doctor.

What level of chlorine is considered acceptable?

WHO gives 5 mg/L as the guideline value for free chlorine in drinking water. The DWI says that most water companies in England and Wales aim to keep the level below 1 mg/l, and Health Canada reports free chlorine in most Canadian systems between 0.04 and 2.0 mg/L.

Why do fish owners need to know which disinfectant is in the water?

Sydney Water explains that the gills and other exposed areas of fish allow chemicals to be absorbed easily, and Health Canada says aquarium owners must use proper aeration or chlorine/chloramine quenching. Sydney Water says leaving water in an open container for 48 hours is usually enough to dechlorinate it, and that an aquarium water conditioner can remove both chlorine and chloramine.

Sources

  • chlorine
  • chloramine
  • water report
  • shower