Cloudy or milky hot water: what causes it

The glass test

Fill a clear glass from the hot tap and set it on the counter. Contra Costa Water District's advice is to let it stand for two to three minutes. If the cloudiness clears starting from the bottom, it's air. If it doesn't clear, or bits settle or float, keep reading.

Clears from the bottom: air

Water in your pipes is under pressure and holds dissolved air. The water district explains that filling a glass drops the pressure, so bubbles appear and the water looks milky or carbonated. In hot water it can come from warming cold lines or from water heated above 140°F, and it often shows up in spring as the weather warms.

Bradford White lists more causes: faucet aerators mixing in air, air added at city pumping stations, air trapped in private well systems, and utilities switching from one well to another. The UK's Drinking Water Inspectorate adds that air is common right after main repairs and normally clears within 24 hours.

Air is harmless. If it's constant in the hot water only, check the heater's temperature setting. Water above 140°F also raises the risk of scalds. See what temperature a water heater should be.

Settles to the bottom: minerals

Mammoth Community Water District explains that as water is heated, calcium and magnesium carbonates come out of solution and form white or tan sand-like deposits in the water heater. Using hot water carries them along, where they clog washing machine screens, showerheads and aerators. Its fix is to flush the water heater at least once a year. Our guide shows how to flush a water heater.

Hard water makes more of it. Meridian, Idaho reported city well water around 7 to 10.5 grains per gallon in 2025 (see our Meridian page).

Floating white flakes: the dip tube

The same water district says floating white particles usually point to the water heater's plastic dip tube, the pipe that carries cold water to the bottom of the tank. As it ages it can disintegrate, sending brittle white pieces into the hot water, from small pebbles to longer shards. The tube can be replaced, and a plumber will usually flush the tank to clear the pieces at the same time.

When the cold is cloudy too

Bradford White notes that milky water can show up in cold lines as well as hot. If both are cloudy, the cause is usually upstream, such as main work or a change in water source. Bridgewater, Massachusetts, for example, began bringing two wells back online through a new treatment facility in October 2026 (see our Bridgewater page). The Drinking Water Inspectorate suggests contacting your water supplier if it lasts more than 24 hours or comes with an odd taste or smell.

Local pages mentioned

• Meridian, ID
• Bridgewater, MA