Toilet bowl water level low

How a toilet bowl refills

When you flush, water from the tank rushes into the bowl and starts a siphon through the curved trap built into the porcelain. The siphon pulls most of the bowl's water down the drain, then breaks with a gurgle. At that moment the bowl is nearly empty, and it needs a refill. That refill comes from the small refill tube on the fill valve, which sprays water down the overflow pipe while the tank fills. The overflow pipe empties into the bowl, so the bowl comes back up to the level set by the top of the trap.

That standing water is what keeps sewer gas out of the house, so a low bowl matters for more than looks. If the refill tube is off or kinked, the bowl stays low after each flush. If the bowl fills normally and then sinks, something is pulling water past the trap: a partial clog that keeps siphoning, a blocked vent pipe that lets other drains suck water out, a rag or string hanging over the trap that wicks it away, or, less often, a hairline crack.

Why the water in the bowl is low

Let's fix it

1. Watch when the level dropsFlush and watch the bowl refill. When the tank stops filling, put a small piece of painter's tape on the inside of the bowl at the waterline, or mark it with a pencil just above the water. Check it again in an hour and the next morning. If the bowl is low the moment the refill stops, the problem is the refill (go to Step 2). If it comes back to its normal level and then drops over time, something is pulling water out (Steps 4 to 6). Also notice whether the flush itself is weak, and whether the toilet gurgles when you run the sink or tub.
   Done

   Enlarge

2. Clip the refill tube back onTake off the tank lid and set it on a towel. Find the thin rubber or plastic refill tube that runs from the top of the fill valve (the tall valve on the left on most toilets). Its other end should clip to the top of the overflow pipe, the open tube in the middle of the tank, with the end pointing down into the pipe. If it has fallen off, clip it back on with the angle clip. Don't push the tube's end down inside the overflow pipe below the water level, since that siphons tank water away. If the tube is cracked, kinked or stiff, a replacement costs a few dollars. Flush and watch: you should see water spraying into the overflow pipe while the tank fills.
   Done

   Something went wrong?

   • Nothing comes out of the tube The fill valve's refill port may be clogged. Turn the water off, take the cap off the fill valve as its instructions show, and flush out debris, or replace the fill valve.

   Enlarge

3. Set the tank and refill levelsLook for a water line marked inside the tank. The water should stop there, or about 1 inch below the top of the overflow pipe if there's no mark. If it stops lower, raise it with the fill valve's adjustment: on most modern float-cup valves, turn the adjustment screw or clip on the side to raise the float. Some fill valves also have a separate bowl refill dial or lever. If yours does, turn it toward more refill as the valve's instructions show. Flush twice and recheck. A tank that's set too low also causes a weak flush, which can leave the bowl short.
   Done

   Enlarge

4. Clear a partial clogA partial clog in the trap keeps a slow siphon going after the flush and leaves the bowl low, often with a weak or slow flush. Use a flange plunger, the kind with a rubber sleeve that sticks out of the bottom. Fit it snugly into the drain opening, push down gently the first time to push the air out, then plunge firmly in and out 15 to 20 times, keeping the seal. Flush to test. If plunging doesn't help, a closet auger (toilet auger) reaches through the trap without scratching the porcelain. See how to unclog a toilet for the full method.
   Done

   Enlarge

5. Check for a blocked vent or a wickRun the bathroom sink or tub for a minute and watch the toilet. If the bowl water bobs, drops or the toilet gurgles while other drains run, the plumbing vent may be blocked, or the drain line further down is partly clogged. See the guide for a gurgling toilet. Clearing a vent usually means working on the roof, which is a job for a plumber unless the roof is low and safe to walk. Also look into the bowl with a flashlight: a piece of string, dental floss, hair or a cloth hanging over the trap can slowly wick water down the drain. Fish it out with a gloved hand or a bent coat hanger.
   Done

   Something went wrong?

   • Only this toilet drops, no gurgling That points away from the vent. Check again for a partial clog or a wick, then for a crack (Step 6).

   Enlarge

6. Check for a crackIf the level drops overnight with no clog, no gurgling and nothing in the trap, look for a crack. Dry the floor around the base and check it again after a few hours. With a flashlight, look closely at the inside of the bowl and the outside of the porcelain for a thin dark line. A cracked bowl can't be reliably repaired and needs to be replaced; don't wait, since a crack can let go suddenly. If water at the base appears only when you flush, it's more likely the wax seal under the toilet. See the guide for a toilet leaking at the base.
   Done

   Enlarge

Watch it done

Low Water Level In The Toilet Bowl-Easy FixBy Helpful DIY on YouTube. Their method may vary a little from ours.

Watch on YouTube

If it comes back

If the refill tube keeps slipping off, the clip may be worn or the wrong size. A new fill valve kit comes with a fresh tube and clip and often fixes a slow or noisy fill at the same time. See the guide for a toilet tank that won't fill.

If the toilet keeps running or refilling on its own between flushes, that's a different leak inside the tank, usually the flapper. See how to fix a running toilet.

If the bowl drops in a toilet that's rarely used, such as a guest bath or a vacation home, some of it may simply be evaporation. Flushing it once a week keeps the trap full and the sewer gas out.