Chlorine in UK tap water: why it's there and how much

Yes, there is chlorine in UK tap water, and it is there on purpose. In England and Wales, water companies must disinfect water and keep a small residual, typically 0.5 mg/l or less, to protect it in the pipes. At these levels, the Drinking Water Inspectorate (DWI) says it is perfectly safe to drink.

Levels vary with where you live, the season and the time of day. This guide covers why chlorine is added, how much reaches your tap, why you smell it, how chloramine differs and how to reduce the taste. For the shower side, see our complete guide to filter shower heads in the UK.

We sell a filter shower head, so every figure here links to its source.

Why do UK water companies add chlorine?

Water companies add chlorine because the law requires them to disinfect water before they supply it. A small amount then stays in the water as a residual, which protects it on the journey through the pipes to your tap.

In England, regulation 26 of the Water Supply (Water Quality) Regulations 2016 requires water companies to disinfect water before supplying it and to verify that the disinfection works. The DWI says companies in England and Wales must also hold a residual chlorine concentration in the pipes that carry water to your taps.

The residual is a safeguard, not the main treatment. The DWI explains that water is already safe when it leaves the treatment works. The trace of chlorine is there to preserve its quality through miles of pipes. Chlorine has about 100 years of safe use for hygiene worldwide, the DWI adds.

Chlorine's record is strong. A 2010 report written by WRc for the DWI puts it plainly: chlorine has probably done more to prevent waterborne disease than any other form of water treatment. So a trace of chlorine at your tap means the system is working as designed.

How much chlorine is in UK tap water?

The chlorine in UK tap water is kept low. In England and Wales, water companies typically hold it at 0.5 mg/l or less, and most aim to stay below 1 mg/l, the DWI says.

Bristol Water gives a fuller picture of one network. It typically adds 0.5 to 1.0 mg/l at the treatment works. By the time water reaches homes, the level is typically 0.1 to 0.8 mg/l. A typical swimming pool, for comparison, holds 1.5 to 5.0 mg/l.

Thames Water, which supplies much of London, says the chlorine leaving its treatment works is usually around 0.9 mg/l. That is just under a gram of chlorine in 1,000 litres of water.

For a global benchmark, a 2003 background document from the World Health Organization (WHO) notes that most disinfected drinking water contains 0.2 to 1 mg/l. The WHO guideline value for free chlorine in drinking water is 5 mg/l. The table gathers these figures as each source published them, checked on 29 September 2026.

Levels vary within one network. The DWI says homes near a treatment works may get a little more chlorine than homes several miles away. Companies must also manage levels so that a minimum reaches the far end of the network.

Season and time of day matter too. Bristol Water says that levels run slightly higher in winter, because cold water holds chlorine for longer. They can also be higher first thing in the morning and in the early evening, when heavy use moves water through the network faster.

To see the range for your own area, ask your water company for its free water quality report. The DWI says it shows the minimum and maximum residual chlorine in your local supply.

Is chlorine in tap water safe to drink?

Chlorine in tap water is safe to drink at the low levels water companies use. The DWI calls it a proven public health measure and says that, at the very low levels used in drinking water, it is perfectly safe to drink.

The WHO guideline value of 5 mg/l is itself cautious: the WHO describes it as conservative. The DWI says levels in England and Wales are well below it, and that much higher concentrations are routinely used safely elsewhere, for example in swimming pools.

Water quality overall is high. In 2025, overall compliance with the drinking water quality standards in England was 99.97%, according to the DWI's Drinking Water 2025 report.

Chlorine itself has no numerical limit in the regulations. The DWI's guide to chlorine disinfection notes that excess levels show up as taste and odour complaints instead. The DWI says the reason chlorine can be a concern at all is that some people are very sensitive to its taste and smell. A chlorine taste is a question of preference, not safety.

Why does my tap water smell of chlorine?

Tap water can smell of chlorine when levels change, when hot water releases it, or when you are sensitive to it. An occasional slight smell is probably due to maintenance work in your area, and the DWI says there is no cause to worry.

Plenty of people notice it. In 2025, water companies in England logged 57,759 consumer contacts about the appearance, taste or odour of tap water, according to the DWI's 2025 figures on consumer contacts. Of those, 5,618 were about chlorine taste or odour. The 57,759 contacts equal 0.97 per 1,000 people.

Maintenance and changing levels

Work on the pipe network sometimes needs higher chlorine levels for a while, the DWI says. The 2010 WRc report notes that complaints are often thought to follow changes in chlorine levels rather than the level itself.

Hot water and the shower

Bristol Water explains that chlorine is more noticeable in hot water, particularly from a combi boiler or an electric shower, which heat water directly. Hot water cannot hold as much chlorine, so it escapes as the water leaves the hot tap or shower head. That is why a hot shower can smell of chlorine when a glass of cold water does not.

Some people notice it more

Sensitivity varies from person to person. The WHO notes that most people can taste chlorine below 5 mg/l, and some at levels as low as 0.3 mg/l.

When to contact your water company

The DWI says to contact your water company if you notice a particularly bad or strong smell, or a TCP-like taste that makes the water unpalatable. Do the same if a new taste or smell does not go away in a short time.

A TCP-like or antiseptic taste is often not chlorine alone. Thames Water links it to chlorine reacting with materials such as appliance hoses, tap washers and plastic kettles, and Bristol Water describes a similar taste from plastic and rubber in plumbing and appliances. Your water company can help check whether the cause is in your home plumbing.

Chlorine or chloramine: which is in your water?

Chlorine and chloramine are the two forms of residual disinfectant in UK tap water. Most supply zones have used free chlorine, while some use chloramine, which lasts longer in the pipes.

The DWI's guide defines the terms. Free chlorine is the total of chlorine, hypochlorous acid and hypochlorite. Chloramine forms when chlorine reacts with ammonia, and counts as combined chlorine. Combined chlorine is a less powerful disinfectant than free chlorine but gives a more persistent residual.

Chloramine is also harder to taste. The 2010 WRc report found that the taste threshold for monochloramine is typically much higher than for free chlorine, with a factor of 6 to 10 not unusual. In one company it studied, chlorinated zones had far more chlorine taste and odour contacts than chloraminated ones.

Which UK water companies use chloramine?

There is no single list in the sources we checked. Chloramine has been the minority choice: in the 2006 to 2008 data behind the WRc report, an average of 5.25% of the supply zones in its data were chloraminated. Bristol Water, for example, says it does not add chloramine. For your own area, ask your water company or check the water quality pages on its website.

One point about our own product. Waterhush's only claim is that it reduces free chlorine, and we make no claim about chloramine. If your area uses chloramine, bear that in mind.

How to reduce the chlorine taste in drinking water

The simplest way to reduce the chlorine taste in drinking water is a covered jug of tap water in the fridge for a few hours. Boiling also reduces chlorine, and a jug filter with an activated carbon cartridge is another option.

1. Fill a clean jug from the cold kitchen tap and cover it.
2. Put it in the fridge for a few hours, or overnight.
3. Drink it within 24 hours, then throw away what is left and clean the jug regularly.

Bristol Water, Thames Water and the DWI all give this advice, and the DWI says cooling tap water in the fridge is all that is needed.

Boiling works too: Bristol Water says boiling the water can reduce the amount of chlorine. If you prefer a filter, the DWI suggests a simple jug filter with an activated carbon cartridge. Follow the maker's instructions and change the cartridge on time, or it will stop working.

Chlorine in shower water: a matter of preference

Chlorine in shower water comes from the same regulated supply as your drinking water, so there is nothing to fix for safety. If you would rather shower with less free chlorine, a filter shower head is designed to reduce free chlorine: that is a preference.

By law, your water company must supply wholesome water suitable for all domestic purposes, including drinking, cooking and washing. The DWI's guidance on home filters and softeners adds that there is no need to install extra treatment at home as a health protection measure.

What people notice in the shower is usually the smell, because hot water holds less chlorine, as Bristol Water explains. Some people simply prefer less of it, and that preference is why someone might filter a shower at all.

Whether shower filters deliver on that is a fair question. The evidence, and its gaps, are covered in do shower filters work? What the evidence really says.

The Waterhush Shower Kit is one option: a round handheld head with the cartridge already fitted in the handle, on its own 1.5 m hose. Waterhush reduces free chlorine, and that is the only claim we make. The cartridge includes four filter media: calcium sulfite, vitamin C, KDF and carbon. What's inside a shower filter, material by material has its own article.

The kit needs a shower with a hose outlet. Electric showers are not confirmed, so check your shower manufacturer's manual first. Is it right for your shower? Check in three questions.

What the figures don't tell you

The figures in this guide do not tell you the chlorine level at your own tap on a given day. They are typical ranges from the DWI, two water companies and the WHO, and real levels shift with distance, season, time of day and maintenance.

• Your local range: your water company's free water quality report shows the minimum and maximum for your supply.
• Your shower: none of the sources above gives a figure for chlorine at the shower head.
• Chloramine today: the zone data in the WRc report dates from 2006 to 2008, so ask your water company for the current position.
• Scotland and Northern Ireland: most figures here come from England and Wales, where the DWI is the regulator. Scotland and Northern Ireland have their own.
• Your nose: a stronger smell does not always mean more chlorine, because changing levels and hot water both play a part.

For anything specific to your address, your water company is the source that can answer.

The bottom line

Chlorine in UK tap water is deliberate and low: water companies must disinfect water, and a small residual, typically 0.5 mg/l or less, protects it in the pipes. At those levels, the DWI says it is perfectly safe to drink.

The main limit is that national figures cannot tell you your own tap's level, so ask your water company. If you would simply rather shower with less free chlorine, a filter shower head is designed for that.