Grit in hot water comes from the city main, your pipes, or the water heater. If cold taps are gritty too, it is likely the supply side, often after a water line repair or hydrant flush. If only hot water carries it, suspect scale and sediment in the tank or pieces of a failed dip tube.
Is it the water supply or the water heater?
Fill a clear glass from a cold tap and another from a hot tap at the same sink. Let both sit for a minute and look at what settles.
| What you see | Where it probably started | First move |
|---|---|---|
| Grit or cloudy water in cold and hot | The city main or your own supply pipes | Run cold water and check for water crew work nearby |
| Grit or flakes in hot only, and it has built up over months | Sediment or scale in the water heater | Plan a tank flush |
| Soft, white or tan plastic-looking bits in hot only, clogging aerators | A disintegrating dip tube | Have the tank inspected |
| Grit that appeared suddenly, right after a leak repair or hydrant work in your area | Disturbed deposits in the main | Run cold taps and give it time |
### What does the city say about sediment?
The City of Phoenix Water Services FAQ says discoloration or sediment may show up after a water leak repair or after a fire hydrant has been flushed near your home or business. It says visible particles are generally an accumulation of iron or minerals that were stirred up. The water may not look pleasant, but Phoenix says it is safe to drink because disinfectant remains in the tap water. If the city's pipes are the cause, Phoenix says the city checks disinfection levels and may flush hydrants to clear the system, and it can take several hours for the water to clear.
Two cautions from that same FAQ are worth passing on. First, cloudiness can interfere with disinfection, so people with severely compromised immune systems, infants and some elderly residents may be at higher risk, and the city says it will visit affected addresses if drinking the water is not advisable. Second, if you wash laundry during a discolored spell, Phoenix recommends not washing it, or using a rust stain remover or regular detergent but not chlorine bleach, because bleach reacts with the iron and can leave a permanent stain.
If the problem started suddenly and cold water is affected, call your water provider rather than your plumber. Phoenix Water Services lists 602-262-6251 on weekdays from 8 a.m. to 5 p.m. and 602-261-8000 on weekends, holidays and after 5 p.m. Other Valley cities run their own utilities, so check your bill for the right number.
What inside the water heater makes grit?
### Sediment and scale
Sediment is minerals that settle out of the water and collect on the bottom of the tank. It builds fastest where water is hard. The Phoenix FAQ says calcium and magnesium from the soils that Phoenix's source water travels through contribute to hardness, and our page on how hard Phoenix water is has the numbers.
Two manufacturer sources point to the same fix. A. O. Smith's annual maintenance checklist includes draining and flushing the tank, and it marks the step very important for gas water heaters. The Department of Energy's Building America guideline says higher temperature settings can accelerate sediment buildup and cites a standard calling for draining twice a year to remove scale and sediment. Rheem's electric heater manual adds that a rumbling noise can mean scale or mineral deposits have built up on the heating elements, and it says to remove and clean them. If you hear popping or rumbling along with the grit, read why a water heater pops or rumbles.
Sediment can sit quietly for years and only show up at the tap when something disturbs it. A plumber can tell you how much is in your tank by draining a little from the bottom. If the hot water is tinted brown or orange rather than gritty, read why only your hot water is brown or discolored.
### A failed dip tube
The dip tube is a plastic pipe inside the tank that sends incoming cold water to the bottom. A Phoenix home inspection firm describes what happens when one fails: the amount of usable hot water can drop significantly, and faucets may become clogged with plastic pieces of the failed tube. The same firm says water heaters fitted with a faulty dip tube between 1993 and 1996 were affected, including State, A. O. Smith and Rheem models, and that a failed dip tube can be fixed without replacing the whole tank.
InspectApedia describes what the debris looks like: white and white-tan particles of varying sizes that are soft enough to mash to powder between a thumb and forefinger. It says the particles clog faucet strainers and that they do not dissolve in acid, which is how you tell them apart from mineral scale. If your debris is soft, pale and does not dissolve in acid, suspect the dip tube. Our page on why you run out of hot water so fast covers the other symptom of a broken dip tube, a short supply of hot water.
### The anode rod
The anode rod is a sacrificial metal rod that protects the tank lining from corrosion. Rheem's manual says it is slowly consumed, and that it should be removed annually for inspection and replaced when more than 6 inches of core wire is exposed at either end. A. O. Smith says to check the anode at least every three years depending on local water conditions, and annually on units with a water softener. A worn-out rod is one more reason to open the tank up and look, because a technician can see it while doing the flush.
What can you do about it yourself?
Start with the low-risk steps.
- 1Clean the aerators and showerhead screens. Unscrew them and rinse out the debris. InspectApedia notes kitchen faucets clogged faster than other faucets in the case it describes, which makes the kitchen aerator a good early check.
- 2Run cold water first if the city was working nearby. Run a cold tap on the lowest level of the house until it clears, then check the hot side. Phoenix says it can take several hours to clear, so give it time before assuming the water heater is at fault.
- 3Look for pattern. Does it show up first thing in the morning, only after long idle periods, or right after someone opened a hot tap hard? A pattern helps the technician.
- 4Flush the tank if it is overdue. A. O. Smith includes a drain and flush in its annual checklist. Our page on how often to flush a water heater in Phoenix gives a schedule for hard water and explains the steps.
A. O. Smith warns that the tank must be full before the power is turned back on, so do not restore power to an electric heater until the tank has refilled. Rheem says not to attempt repair of electrical wiring, heating elements or other safety devices, so leave anything beyond a basic flush to a professional.
When should you call a plumber?
Call if grit keeps coming back after you clean the aerators and flush the tank, if the debris looks like plastic, if you have not flushed the tank in years and it is old, or if the water heater is leaking, noisy or making less hot water. A plumber can drain the tank and see what comes out, check the anode rod, and tell you whether the tank is worth keeping. Our page on whether to repair or replace a water heater covers that decision, and why hard water damages plumbing explains why scale keeps returning.
HQ Plumbing and Air is licensed and insured, takes emergency calls 24/7, and gives free estimates with an upfront price before any work starts. You can also see our water heater services.