If you have found grit in your hot water, in the bottom of a sink strainer, or in the bottom of a glass, your first instinct may be to drain the water heater. That can help, but it is smarter to figure out where the grit is coming from first. In St. Louis homes, sediment usually comes from one of three places: the water heater tank itself, the plumbing inside the house, or the water that arrives from the street. A few simple checks can narrow it down before you spend time on a repair.

Start by noticing which side of the house has the problem

Run the cold tap in the kitchen and the hot tap in the same room. Then do the same at a bathroom sink and at an outside spigot if you have one. Watch what comes out, and take notes on which fixtures show grit.

  • If grit appears only on the hot side, the water heater tank or the hot water pipes are the most likely source.
  • If grit appears on both the hot and cold sides, the problem is more likely in the supply line, the service connection, or a shared fixture.
  • If grit appears only at one faucet, check that faucet's aerator and inlet screen before blaming anything else.

Collect a clean sample to look at

Fill a clear glass jar or a clean white cup from the cold tap, then let it sit undisturbed until it settles. Repeat the same step with hot water from a different fixture. Compare the two samples side by side in good light.

Fine, sandy particles that drop quickly to the bottom often point to material moving in the supply or left over from work on the street. Flakes that look like rust, dark specks that smear, or a hard crust that breaks apart can point to corrosion inside the piping or tank. White, chalky residue that stays on the glass points more toward mineral buildup, which is common with hard water across the St. Louis area.

Check the water heater tank

Sediment settles to the bottom of a tank over time, and it can be stirred up when demand is high or when the tank has been running hot for long periods. If the hot side is the only side with grit, look at the tank and its connections before opening anything.

  • Check the gas or electric controls and the labeled manufacturer information before doing any work on the unit.
  • Look for drips, staining, or rust at the fittings on the top of the tank.
  • Note the age of the tank and whether it has ever been drained. Older tanks without regular maintenance tend to collect more sediment.

If you decide to drain the tank, let the water cool first, because hot water can cause burns. Attach a hose to the drain valve, run it to a safe outdoor spot or a floor drain, and open the valve slowly. Keep a close eye on the discharge. If it runs cloudy at first and then clears, the tank was likely holding sediment. If it stays gritty or dark, the problem may be in the supply or in the pipes rather than the tank alone.

Look at the street supply

Sediment that appears suddenly across a whole block or neighborhood often comes from work on the water main or from a change in flow. If you notice grit in several homes nearby, or if the problem began right after street or utility work, contact your water provider and ask whether there has been recent work in your area. A provider can tell you whether any service was disturbed and what they are doing about it.

Do not assume that a temporary sediment event is a permanent problem. Many homeowners run their taps for a while after notice of work, then find the water clears. If the grit keeps returning after several days, treat it as a plumbing or source question that needs more investigation.

When a home test is not enough

A simple jar test and a visual check are useful for sorting out likely causes, but they cannot tell you what a particle is made of or whether the water meets any particular standard. If you are worried about metals, or if the grit is dark, heavy, or accompanied by changes in taste or color, consider sending a sample to a certified lab. A lab can identify the material and report results in a form you can compare with official guidance. Ask the lab what sample container, preservation, and holding time they require before you collect the sample.

A simple next-step order

  1. Note which fixtures show grit and whether it is hot only, cold only, or both.
  2. Collect and compare settled samples from hot and cold water.
  3. Clean the aerators and screens at the affected faucets.
  4. If the hot side is the problem, drain the tank carefully and watch the discharge.
  5. If the problem spans several homes or began after street work, contact your water provider.
  6. If the material is unclear or you are concerned about what it contains, use a certified lab before deciding on a repair.

Working through these steps in order keeps you from replacing parts or draining equipment when the real source is somewhere else. Write down what you observe each time, because a dated list of what you saw makes it much easier for a plumber, a provider, or a lab to help you.