Quick Answer:
If you see sand, grit, or cloudy water right after replacing a valve, it’s usually loose material shaken free from the pipe or the valve itself. Don’t assume it’s pipe scale falling apart — first check screens and flush the line. Clean any removable screens, run cold water until it clears, and inspect fixtures before using appliances.
Why This Happens
Replacing a valve disturbs the flow and can dislodge mineral deposits, rust, or trapped grit. Sediment can come from the pipe, from the supply main, or from debris caught in the fitting during installation. It often looks like what you’d see after a utility event — similar to Cloudy water after city outage — or the loose material that shows up when water is restored to a house: Grit after turning water back on.
Step-by-Step What to Do
Step 1 — Stop and assess
- Don’t use hot water yet. Sediment can be drawn into the water heater and settle there.
- Open a nearby cold tap slowly to let pressure normalize and see how widespread the issue is.
Step 2 — Inspect the new valve and screens
- Shut the valve off if the installation allows, then remove any removable screens or filters on the valve or adjacent fittings.
- Inspect those parts visually and rinse them. Inspect new valve screens for trapped grit.
- If the valve has internal debris you can’t access, open a downstream faucet to flush the line while the valve is open briefly to push grit out.
Step 3 — Flush the system
- Open the lowest cold-water tap in the house (basement or first floor) and run it for several minutes until water clears.
- Check other fixtures and remove aerators or shower heads to clear trapped particles and rinse them.
- Run only cold water first; avoid sending sediment into the water heater.
Step 4 — Recheck and restore use
- Once water runs clear at multiple taps, reinstall cleaned aerators and screens.
- Turn on hot water and check the water heater by running a hot tap briefly; if it’s dirty, you may need to flush the heater per the manufacturer’s steps or call a pro.
What Not to Do
- Do not tighten valves before clearing sediment. Tightening can trap grit against seats and cause leaks or poor operation.
- Do not rely on chemical cleaners to dissolve grit in the supply lines.
- Avoid running high-demand appliances (dishwasher, washing machine) until water is visibly clear to prevent clogs.
When to Call a Professional
- If sediment keeps appearing after thorough flushing and screen cleaning.
- If you can’t access or clean the valve internals safely, or if the valve leaks after you clean it.
- If multiple fixtures show persistent discoloration or if you suspect corrosion inside the piping.
Safety Notes
- Wear gloves and eye protection when handling debris or removing screens.
- Be cautious with hot water — do not run hot taps while flushing until cold water clears to avoid scalding and contaminating the water heater.
- If water looks rusty, smells odd, or you’re unsure about safety, avoid drinking it and call your water utility or a plumber.
Common Homeowner Questions
- Is this dangerous to drink? Usually not if it’s only mineral grit, but avoid drinking if it’s rusty, smelly, or persistent; run water until clear.
- Will this damage appliances? Sediment can clog screens and strainers; clean filters and delay using appliances until water is clear.
- How long will it take to clear? Often minutes to an hour of flushing; if it continues beyond that, get professional help.