Discolored water has two possible homes: the water supply and pipes, or the water heater. The single most useful thing you can do before calling is run cold water at the same tap and see whether it's clear. If only the hot water is tinted, the heater is almost certainly involved.
Hot water looks wrong? Start here
- Fill a clear glass from the cold tap, then one from the hot. Compare them.
- Note the color: orange or brown, yellow, black specks, white grit or milky.
- Check whether neighbors or the whole street have discolored water.
- Note roughly how old the heater is, from its label.
What each color usually points to
Orange, red or brown, hot water only. Rust from inside the tank. The anode rod has been consumed and the steel is corroding. The most common and most significant finding.
Orange or brown in hot and cold. The supply or the house plumbing, often old galvanized steel pipes in older homes, or temporary disturbance in the mains.
Black specks or flakes. Deteriorating rubber in washers or connectors, or sediment stirred up from the tank floor.
White grit or flakes. Mineral scale from the tank or a deteriorating dip tube. Very common in hard-water areas.
Milky water that clears from the bottom up. Air bubbles. Usually harmless.
Blue or green staining at fixtures. Corrosion of copper plumbing rather than the heater, though a heater set very hot or thermal expansion can play a part.
Why tanks start to rust from the inside
A steel water heater tank is lined with a glass-like coating, but no lining is perfect. The anode rod protects the exposed spots by corroding in their place. Once it's used up, the tank's own steel takes over that role, and rust begins to appear in the hot water. Heat speeds the process up, which is why the hot side shows it first.
The age at which this happens varies enormously with water chemistry, temperature settings and whether the anode was ever checked. That variation is why two neighbors with identical heaters can have very different experiences.
California factors
Hard and aggressive water. In much of the inland south and the Central Valley, mineral-heavy water accelerates anode consumption and adds sediment that can carry color. Hardness and water chemistry vary by district; your water provider can tell you about your supply.
Softened water. Homes with water softeners often see anodes consumed faster. That doesn't mean softeners are a bad idea, just that the anode deserves checking more often.
Older housing. Pre-war and mid-century homes, common in the Bay Area and the older cores of Los Angeles and Sacramento, may still have galvanized steel supply lines. Rusty water in both hot and cold often traces back to them rather than the heater.
Well water. In foothill and rural communities on private wells, iron and manganese in the water itself can cause staining and tint that has nothing to do with the heater. Filtration questions go to a water treatment specialist.
Seismic strapping. If rusty water leads to a replacement, securing the new tank is part of the job; the installer confirms what applies at your address.
A quick description on the phone often narrows it down immediately.
What not to do
Leave these to the technician
- Draining or flushing the tank yourself while it's under pressure
- Removing the anode rod or opening fittings on the tank
- Operating the relief valve to "clear" the water
Running the cold tap to see whether it clears is fine. So is keeping a sample in a clear glass to show the technician.
How the technician handles it
The technician confirms whether the discoloration is hot-only, checks the age and condition of the heater, and where appropriate inspects the anode rod. A heavily consumed anode on a tank that's otherwise sound can be replaced, often along with a flush to clear loose sediment. Rust coming from a tank that's corroded significantly, especially an older one, points to replacement, and the technician will price both options honestly. If the source is the pipes or the supply rather than the heater, they'll tell you that too, rather than selling you a tank.
What affects the cost
| Finding | Likely remedy |
|---|---|
| Spent anode, sound tank | Anode replacement, often with a flush. A modest visit. |
| Anode hard to remove or no overhead room | More labor, or a segmented replacement rod. |
| Corroded tank | Replacement, priced with strapping, connections and haul-away. |
| Deteriorated connectors | New connectors; usually inexpensive. |
| Supply or pipes | Not a heater job. You'll be told so. |
How long it takes
Diagnosis is usually quick. An anode replacement and flush is typically a single visit, though a seized anode takes longer. Replacement depends on the unit and access, and the technician will give you a realistic plan.
Useful before rusty water turns into a leak.
Discolored hot water questions
When the cold water runs clear and only the hot is tinted, the water heater is the most likely source. Usually the anode rod has been used up and the steel tank has started to corrode from the inside. On an older tank that's a strong sign replacement is near. On a younger one, an anode replacement and flush may help, depending on what the technician finds.
Probably not. Discoloration in both usually comes from the supply: work on the water mains, a change in how the water is being routed, or old galvanized pipes in the house. Water district work typically clears within hours to a day. If it persists, or the house has old steel pipes, a plumber can look at the lines; the heater itself may be fine.
Black flecks can be bits of a deteriorating rubber washer or hose, fragments from certain fittings, or sediment disturbed from the tank. The technician will look at the flexible connectors, washers and the tank to find the source. It's worth mentioning whether the specks feel rubbery or gritty.
Milky water that clears from the bottom of a glass upward is usually just tiny air bubbles and harmless. Cloudiness that settles as white grit is more likely mineral sediment from the tank, common in hard-water areas. The second points to a heater that could use flushing or has heavy scale.
We can't give health advice, and it's reasonable to avoid drinking discolored water until the cause is known. Hot water from a water heater generally isn't recommended for drinking or cooking anyway. For questions about your supply's quality, contact your water provider. Our job is finding whether the heater is the source and fixing it.
If the tank lining is still intact and the rust is early, replacing a spent anode can slow further corrosion. If the tank has already corroded significantly, a new anode won't reverse that, and the rusty water usually returns. The technician will inspect the old anode and the water to judge which case you're in.
Not always, but on an older tank with rust only in the hot water, a leak often follows sooner or later. That makes it a good time to plan a replacement on your schedule rather than waiting for water on the floor. The technician can give you an honest view of how far along it seems.
A pale yellow tint can come from iron at low levels, from sediment, or from organic material in some supplies, including some well water. If it's only in the hot water, the tank is a likely contributor. If it's in both, the supply or the pipes are more likely. Say whether you're on a private well when you call.