Cloudy, Brown or Funny-Tasting Tap Water? A Symptom-by-Symptom UK Guide
Updated: 1 day ago
Last reviewed: September 2026
Quick answer When your water tastes funny, smells odd or looks cloudy, the cause usually comes from inside your home — pipes, taps, appliance hoses, the hot water system or water left standing — rather than from the water supply. Three quick questions usually narrow it down: Is it every tap or just one? Hot, cold or both? Did it start suddenly? Use the table below to find your symptom. Two things you should never ignore: brown or black water that doesn't clear, and any fuel, oil or sewage smell — contact your water company straight away.
Not sure what's causing it? Work through the symptoms below, or go straight to our "Which water test do I need?" guide.
Start here: three questions that narrow it down
Every tap, or just one? One tap points to that tap, its washer or the pipe behind it. Every tap points to the supply or the main.
Hot, cold or both? A smell only on the hot side is usually your boiler, cylinder or water heater — not the drinking water.
Sudden or gradual? A sudden change often follows mains work, a burst or plumbing work. A gradual one points to pipes, a filter or a supply change.
The glass test: fill a clean glass from the cold kitchen tap, take it to another room, and smell or look at it there. Sink drains and damp cupboards cause a lot of "bad water" smells that aren't the water at all.
Symptom finder
What you notice | Most likely cause | Do this first | Test or call if… |
Cloudy or milky, clears from the bottom up | Tiny air bubbles | Leave the glass for 2 minutes | It doesn't clear, or keeps coming back |
White bits or film, kettle scale | Hardness (calcium) | Nothing — UK rules set no health standard for hardness | You want to know your hardness for appliances |
Brown, orange or yellow | Iron or manganese stirred up in the main or your pipes | Run the cold kitchen tap for a few minutes | It doesn't clear, affects neighbours, or keeps happening → call your water company |
Black specks | Perished tap washer or hose, or manganese | Check whether it's one tap only | It's every tap |
Chlorine or bleach smell | Normal disinfection, higher near the treatment works | Chill a covered jug in the fridge | It's much stronger than usual |
TCP, antiseptic or "medicinal" | Chlorine reacting with rubber or plastic in taps, kettles or appliance hoses | Try water boiled in a pan, not the kettle | It's in every tap after checking appliances |
Earthy or musty | Water standing in pipes, or natural compounds from reservoirs in warm weather | Run the cold tap; do the glass test | It persists after flushing |
Rotten eggs | Hydrogen sulphide — often the hot water system or a drain | Check hot vs cold, and smell away from the sink | It's in the cold water on a private supply |
Metallic or bitter | Copper, iron or zinc from pipes, especially after water has stood | Run the cold tap until it's cold | It persists — and remember lead has no taste |
Petrol, diesel or oil | Fuel soaking through plastic supply pipes | Don't drink it | Call your water company immediately |
Sewage | Plumbing or drainage fault | Do the glass test | It follows the water → call your water company |
Why is my tap water cloudy or white?
Cloudy water that clears from the bottom of the glass upwards within a minute or two is air. It happens when water is under pressure in the pipes — often in cold weather or after mains work. The Drinking Water Inspectorate (DWI) explains: "White or cloudy water is normally caused by tiny air bubbles trapped in the water, usually when the water has been turned off nearby."
If cloudiness doesn't clear, or you see white particles or a scum on hot drinks, it's usually calcium from hard water. Hardness affects taste and limescale. It has no health-based limit: the Drinking Water Inspectorate says UK regulations "do not specify standards for hardness, calcium or magnesium".
Cloudy water that appears after plumbing work is a slightly different case — see Cloudy Tap Water After Plumbing Work: When to Flush and When to Test.
Brown, orange or black water from the tap
Discoloured water is almost always iron or manganese. Older cast-iron mains slowly corrode and build up deposits, which get stirred up when there's a burst, a repair or a change in flow. The DWI also notes it can come from the pipe connecting your home to the main, or from your own plumbing.
What to do:
Run the cold kitchen tap at a steady rate for a few minutes. Don't use hot taps, washing machines or dishwashers until it clears (it can stain washing).
If it doesn't clear, or neighbours have it too, call your water company. Keep a sample in a clear bottle and note the time.
The Drinking Water Inspectorate says: "If your tap water is suddenly discoloured, you should not assume that it is safe to drink until you have sought advice from your water supplier." until your supplier has told you it is. That's the DWI's own advice.
On a private supply, brown or orange water usually means naturally high iron or manganese in the source, and it's worth testing before choosing any treatment.
Tap water smells of chlorine or bleach
A light swimming-pool smell is normal — chlorine is added at the treatment works to kill germs. It can be stronger if you live near the works or when demand is high. Thames Water and Welsh Water both suggest filling a jug and keeping it covered in the fridge; the smell fades. More on levels in What Is the Level of Chlorine in UK Tap Water?
Tap water tastes of TCP or antiseptic
This is one of the most common complaints, and it almost never comes from the water supply. Chlorine reacts with rubber and plastic parts — tap washers, kettle parts, and especially the hoses of washing machines and dishwashers. If an appliance has no non-return valve, water that has sat in its hose can flow back into your pipes.
How to find it:
Boil water in a saucepan and taste it next to kettle water. If only the kettle tastes odd, it's the kettle. (With a new kettle, boil and discard a couple of fills first.)
Turn off the isolating valves to your washing machine and dishwasher overnight. If the taste disappears, a plumber can fit a non-return (check) valve.
If a single tap is affected, replace its washer.
Water smells earthy or musty
Musty smells usually come from water that has stood in rarely used pipes — a spare bathroom, a house left empty, pipes in a warm cupboard. Some reservoirs also produce natural earthy-smelling compounds in warm weather. Welsh Water suggests taking the water outside or into another room to smell it, because sink drains often cause the smell. Run the cold tap for a few minutes; if you've been away, run every tap.
Tap water smells like rotten eggs
The smell is hydrogen sulphide. Where it comes from matters:
Hot water only: usually the hot water cylinder or water heater. A heating engineer can check it.
Only near the sink: usually the drain or waste trap, not the water. Do the glass test.
Cold water on a private supply: can come from the source itself (some groundwater contains sulphides) or from bacteria in pipes or tanks. Test it — and see Is Borehole or Well Water Safe to Drink?
Water tastes metallic or bitter
A metallic taste usually means copper, iron or zinc has dissolved from your pipes, especially after water has stood overnight or in homes with long runs of pipework. Run the cold tap until it's noticeably colder, and use that water for drinking. Welsh Water also points out that dishwasher detergent left on glasses can taste bitter.
Important: taste isn't a reliable guide to lead. The DWI says that if your home was built "before 1970 – it may have lead pipes". The only way to know is to test — see Understanding Lead Contamination in Drinking Water.
Fuel, oil or sewage smell
Don't drink the water. Fuel and oil spilled near a plastic supply pipe can soak through it over time. Contact your water company straight away so they can investigate.
When a test helps
Most taste and smell problems are solved by the checks above. Testing is worth it when:
a symptom persists after flushing and checking appliances,
you're on a private supply and anything changes,
you live in an older home and have noticed metallic tastes, or
you want evidence before spending money on filters or treatment.
Symptom that persists | Useful test |
Metallic taste in an older home | |
Any change on a private supply | E. coli Test first, then a Complete Kit |
Chlorine taste you want to quantify | |
Not sure |
A home test is a screening step. If a result is unexpected or affects health decisions, confirm it with an accredited laboratory or your water company.
Who to contact
Mains water: your water company — for discolouration that won't clear, fuel/oil or sewage smells, or anything affecting neighbours.
Private supply: your local council's environmental health team.
Inside your home: a WaterSafe-approved plumber for washers, valves and pipework.
For the wider picture, see our Taste & Smell Problems guide.
Test your water
Once you've narrowed down the symptom, a quick home screen tells you whether it's worth taking further.
SustainWater home tests are screening tools. If a result is unexpected, or a health, legal or money decision depends on it, confirm it with an accredited laboratory.
Frequently asked questions
Why does my tap water taste different from normal today? Short-lived changes often follow mains work or changes in chlorine levels when demand rises. If it lasts more than a day or two, or neighbours notice it too, tell your water company.
Why does the kitchen tap taste different from the bathroom tap? They may be fed differently. In many older homes the bathroom cold tap comes from a loft tank. See Is UK Tap Water Safe to Drink?
Is cloudy tap water safe to drink? If it clears from the bottom up, it's almost certainly air. The Drinking Water Inspectorate says: "White or cloudy water is likely to be caused by air trapped in the water and is not harmful to health." If it doesn't clear, or it has lasted more than 24 hours, contact your water company.
Why does my hot water smell of rotten eggs but not the cold? The cause is almost always in your hot water cylinder or heater, not the supply. Ask a heating engineer to check it.
Can a water filter fix a bad taste? Often, yes — carbon filters reduce chlorine tastes and smells. But a filter hides a symptom; it doesn't tell you the cause. For metallic tastes or private supplies, test first.
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