Quick Answer:
If your toilet is refilling at random after a recent city water outage, the most likely cause is small sediment or a pressure surge making the fill valve stick or the inlet screen partially block. Start with simple checks: confirm the flapper and overflow are correct, shut off the toilet supply, remove and clean the fill valve inlet screen, then retest. If cleaning does not stop the random refills, call a plumber.
Why This Happens
City outages and the restoration of service can move sediment and change pressure in the pipes. That debris can lodge in the small inlet screen or valve mechanism inside the toilet tank. A stuck or partially blocked fill valve can let a trickle through, trigger the float to reset, and cause intermittent or random refills.
Similar behavior can follow other events like winterization or long idle periods. If you’ve seen related issues before, check articles such as Phantom flush after winterization for more on how small changes produce odd toilet behavior.
Step-by-Step What to Do
1. Observe and note the refill pattern
- Listen to the toilet for when the refill happens (right after flushing, randomly, or only at certain times).
- Check whether the bowl is constantly losing water or if the tank is visibly losing water into the bowl.
2. Check the easy wear items
- Inspect the flapper or seal for warping, mineral buildup, or debris under it.
- Make sure the overflow tube isn’t cracked and that the water level is set below the tube top.
3. Shut off water and remove the toilet tank lid
- Turn the toilet supply valve clockwise until it stops.
- Flush to drain most of the water from the tank so you can work safely.
4. Clean the fill valve inlet screen and retest refill behavior
- Locate the fill valve (usually on the left inside the tank). At its base or where the supply line enters the valve is a small mesh or rubber inlet screen.
- Carefully remove the screen if it’s removable. Rinse it under clean water and gently scrub away sediment with an old toothbrush.
- If the screen is not removable, flush the supply briefly (with the supply valve slightly open and tank drained) to try to clear debris, then wipe accessible areas clean.
- Reassemble, open the supply, let the tank refill, and watch for the previous random refill behavior.
5. Adjust or replace the fill valve if needed
- If cleaning stops the issue, monitor for a day or two. If the problem returns, the fill valve may be worn and should be replaced.
- If the valve still sticks, note whether the float or arm moves freely; replace the entire valve assembly if parts are corroded or broken.
What Not to Do
- Don’t force a sticking fill valve; plumber if cleaning fails.
- Don’t pour strong chemical cleaners into the tank to try to dissolve grit — that can damage seals and internal parts.
- Don’t ignore repeated refills; ongoing leakage wastes water and can hide a failing valve or seal.
When to Call a Professional
- If cleaning the inlet screen and replacing simple parts does not stop the random refills.
- If you cannot shut off the supply valve or the valve leaks at the connection to the tank.
- If you see consistent loss of water into the bowl despite a new fill valve or flapper, as this could indicate a more complex issue.
Safety Notes
- Turn off the toilet supply valve before working. If you are unsure where it is, shut off the house main water.
- Wear gloves and eye protection when handling dirty water or scraping mineral deposits.
- Avoid using metal tools inside plastic valve parts; use gentle force to prevent cracking or other damage.
Common Homeowner Questions
- Why did this only start after the outage? Sediment and pressure surges from service restoration are common triggers.
- Can I leave the tank off while I wait for a plumber? You can shut the supply valve to stop refills; avoid using that toilet until fixed if the bowl leaks.
- Is this an emergency? Not usually an urgent emergency, but fix it soon to prevent wasted water and potential higher bills.
If random refills continue after you’ve cleaned screens and replaced worn parts, consider contacting a licensed plumber — especially if you can’t stop leaks or the valve assembly appears damaged.
Toilet refills only at night