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Why is my tap water cloudy or milky?

Start here: is it the hot tap, the cold tap, or both?

Run each tap on its own before you do anything else. Which taps are affected narrows the cause more than any description of the symptom can.

Hot tap only

Dissolved air coming out of solution

Hot water holds less dissolved gas than cold, so heating drives air out of solution as a cloud of fine bubbles. Cloudy hot water that clears from the bottom of the glass upward is air, every time, and there is nothing to treat. If it also leaves a white film on the kettle, that is scale from hardness, which is a separate and equally harmless matter.

Cold tap only

Aerated water, or fine suspended sediment

Cold water can arrive full of air after work on the main or a pressure change, and it clears bottom-up in the same way. If the glass never clears, you are looking at suspended particles instead. That is turbidity, and unlike air it is something your utility measures and can act on.

Hot and cold

A change on the supply side

Cloudiness at every tap that does not clear on standing points upstream of your fixtures — sediment lifted off the pipe wall in the service line or the main, or a change at the treatment plant. The tell is whether your neighbors have it too, which is one text message away.

On a city water supply

The usual municipal trigger is work on the system. EPA's own distribution-system guidance describes flushing as a maintenance technique used to remove stagnant water, restore disinfectant residual, remove loose deposits and scour pipe surfaces — and it is candid that, depending on velocity and method, flushing can loosen and mobilize sediment in the pipe without fully removing it, and that conventional flushing through an open hydrant can spread sediment to nearby customers if it is not done carefully. That is your cloudy glass, described from the utility's side. It is worth knowing what the federal turbidity rule actually measures, because it is not your tap: for systems using conventional or direct filtration, turbidity can never exceed 1 NTU, and 95 percent of samples in any month must be at or below 0.3 NTU. Those samples are taken on filtered water at the plant. A system can meet that standard exactly and still deliver a cloudy glass to your kitchen after a main is disturbed, because the material was picked up in the miles of pipe that come afterwards. Persistent cloudiness in one building while the water at the street runs clear is a plumbing problem, not a utility problem.

On a private well the causes are different, and we answer that version of the question separately. Read the private-well answer.

What your own utility reports

Enter your ZIP code to see the utility-reported values behind this symptom, taken from the water quality data your system files with regulators. Where your utility reported nothing, this says so rather than filling the gap with an estimate.

What actually fixes it

Do the glass test before you spend anything. If the cloud clears from the bottom up within a minute or two, it is air: harmless, self-resolving, and no filter improves it, because there is nothing there to remove. If the glass stays uniformly cloudy, the next call is to your utility rather than to a filter store — EPA lists customer complaints about turbidity as one of the reasons a system flushes a section of main, so the complaint is the mechanism by which this gets fixed. If instead the water is clear but leaves white deposits, you have hardness rather than turbidity, and USGS is unambiguous that hardness is not a health concern, only a nuisance. A point-of-use filter treats the one tap it is fitted to and leaves the rest of the house exactly as it was; on a supply-side problem that is money spent on the wrong side of the meter.

When it is worth testing

  • A glass of the water is still cloudy after standing.

    Ask your utility for recent turbidity results for your service area. If the cloudiness is confined to your building, a certified-lab turbidity result on a cold-tap sample is what separates your plumbing from the main — and it gives the utility a measurement from your address instead of a description.

  • The water is clear but leaves white scale on the kettle, the shower screen and the taps.

    A hardness result, expressed as milligrams per liter of calcium carbonate. USGS classifies 0 to 60 as soft, 61 to 120 as moderately hard, 121 to 180 as hard, and above 180 as very hard. Hardness has no EPA standard of its own, primary or secondary — the closest is the secondary standard for total dissolved solids at 500 mg/L, which lists hardness and deposits among its effects — so water systems are not required to publish a hardness figure and plenty of them never do. That is why the lookup above answers hardness for the city rather than system by system: one figure, taken from the utilities' own reported hardness where any of them reports it, and from county sampling where none does. Each value carries a label saying which of the two it is, a county estimate describes the area rather than your tap, and where we have neither the lookup says not reported. This is a comfort and appliance question rather than a safety one, so the number's job is to tell you whether treating it is worth the cost, not whether the water is safe.

  • The cloudiness returns every time work is done on the street and takes days to clear.

    A certified-lab turbidity result taken while the water is cloudy, plus a note of the dates. A repeating pattern tied to specific work is the kind of evidence that moves a section of main up a utility's flushing schedule, and EPA's guidance describes exactly that: spot flushing at locations with a history of customer complaints.

Frequently asked questions

Is cloudy tap water safe to drink?

Usually yes, because the usual cause is dissolved air, which is harmless and clears on its own. The test that separates the harmless case from the one worth pursuing takes a minute: fill a clear glass and watch it. Air clears from the bottom upward as the bubbles rise. Water that stays uniformly cloudy is carrying suspended particles, and that is the case to raise with your utility rather than to shrug at.

Why did my water go cloudy after work on the street?

Because that work changed the pressure and the direction of flow in the main. EPA's distribution-system guidance is explicit that flushing can loosen and mobilize sediment in the pipe without fully removing it, and that conventional flushing needs care or sediment spreads to nearby customers. Repairs and main breaks do the same thing without the planning. It is the most common reason municipal water turns cloudy for a day, and it normally clears once the disturbed water has passed through.

Does cloudy water mean my utility is breaking the turbidity standard?

Not by itself. The federal requirement for systems using conventional or direct filtration is that turbidity never exceeds 1 NTU and that 95 percent of monthly samples are at or below 0.3 NTU — measured on filtered water at the treatment plant, not at your sink. Material picked up in the distribution system after that point is a real problem worth reporting, but it is not the same measurement, and treating the two as one is how these conversations usually go wrong.

Do I need a filter for cloudy water?

Not for air, which no filter removes and which needs no removing. For sediment, a filter can clear the tap you install it on, but it does nothing about material arriving through the meter and nothing for the other taps in the house — and your utility needs to know about that either way. For hardness, USGS is clear that it is a nuisance rather than a health concern, so treating it is a preference about appliances and skin, not a safety decision. Establish which of the three you have before deciding you need equipment.

Other tap water symptoms

Sources

All tap water problems by symptom

By TapWaterData Team

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