How to Fix a Toilet That Randomly Runs

No one has used the bathroom for a while, yet the toilet randomly runs, starting to fill up like it was recently flushed. To more superstitious folks, it might seem like the bathroom is being haunted. For us, it sounds like the problem is the water level in the tank.

Why Does My Toilet Keep Randomly Filling?

A lot of random plumbing issues can occur with toilet flushing such as leaks or even changes to your shower temperature. Normally when you flush, however, the water stops running after a few seconds. So if the toilet keeps running randomly on and off, then you know you have an issue. This is often referred to as a phantom flush.

When you flush the toilet, a number of things happen at once. You pull a lever that lifts the flap. That flap covers the channel that takes water from the tank to the bowl. When it opens, all of the water gushes down to the bowl and into the drainage pipe, then the flap closes to seal the tank once more.

A float in the tank controls the toilet filling valve, which lets water back into the tank after you flush. When enough water fills the tank and the float rises into place, it shuts the toilet filling valve off.

This is all usually over in less than a minute if everything works correctly.

If a toilet randomly runs for a few seconds and empties without flushing, it’s likely the result of a cracked toilet flapper, the chain being caught, the float needing to be lowered, or the refilling tube needing to be repositioned.

Problem 1: Toilet Flapper Could Be Cracked

If your toilet randomly runs off and on for a few seconds, it is likely due to a broken flapper. While the flapper is supposed to drop down and re-seal the tank when enough water has gone through, a cracked or decaying flapper will allow water to keep flowing through and run periodically.

The flapper is what seals the water tank, so when it’s raised, it allows water to go into the toilet bowl.

Problem 2: Chain Might Be Caught

If you’ve tried replacing the flapper, it could be the chain is caught. When you pull the lever to flush the toilet and lift the flap, there’s a chain attached to help that happen. Issues with the chain can result in the water running continuously.

For example, if the chain is too long or on the wrong link then it can get caught under the flapper and prevent it from sealing. If it’s too short, it won’t seal at all.

Problem 3: Float May Need to be Lowered

Toilets can overflow or run continually if there’s too much water in the tank. This can occur if the float is too high, causing the water to fill up and pour into the overflow tube. When your toilet keeps running intermttinetly due to an excess of water in the tank, then the float needs to be lowered so the tank doesn’t fill up as much.

Problem 4: Refill Tube Could Require Repositioning

A running toilet can occur when the refill tube is too long or improperly positioned, causing it to continually pump water into the bowl. The refill valve creates a suction effect and pulls water out of the fill valve and into the toilet. If this is the case, the tube needs to be shortened or positioned just above the opening of the overflow. 

Solutions to Fix Your Toilet

Usually, when a toilet randomly runs for a few seconds, it isn’t an overly complicated job to resolve. You may need some tools before beginning, including but not limited to the following: 

  • Rubber gloves
  • A sponge or towels
  • Cutting pliers
  • Multi-bit screwdriver
  • Replacement fill valve
  • Other replacement parts for your toilet

Bathroom plumbing can be different from many other kinds of plumbing. For any major repairs, it’s always recommended to contact a licensed plumber to inspect whatever plumbing issue you have on hand. This will ensure the problem is properly repaired and maintained.

If there is ever a plumbing issue you aren’t sure how to handle, aren’t confident handling, or simply don’t want to deal with, always rest assured that an expert plumber can handle the issue for you.

If you’re looking to tackle your running toilet on your own, then here are some simple solutions you can try. If you try them and your toilet keeps running anyway, call in the experts to help.

Solution 1: Replace the Flapper

If the flapper looks at all damaged, try turning off the toilet’s water supply and then flushing the toilet. Use a sponge to clean up any leftover water and then unhook the flapper and replace it with a new one. Turn the water supply back on and test.

If the toilet randomly runs or the tank starts filling by itself, it’s a sign that the flap is failing. This means it’s not properly covering the hole to the tank and is allowing water to escape and the level to drop.

If the tank is filling up past where it should be, the pressure could cause even a brand new flap to fail. But if the water level is normal and the flap still isn’t able to seal the tank, replacement is the best course of action.

Solution 2: Lower the Float or Move the Chain

If the float is what’s causing your running toilet, you’ll have to lower it. You do so with the float arm by loosening or tightening the screw until the float arm lowers. If the chain is getting in the way or causing issues, simply adjust how long or short it is so it doesn’t get in the way but also doesn’t keep the flapper open.

Solution 3: Shorten the Refill Tube

Pull the refill tube out of the overflow. Hold it above the opening of the overflow, and then trim it off at that height precisely with cutting pliers. Clip it to the side over the overflow tube again to keep it in the right place.

Call a Plumbing Professional to Fix Your Toilet

If none of these quick fixes work or if you just don’t feel comfortable trying to do the job yourself, call 703-214-5611, don’t hesitate to call John C. Flood, the professional plumber in Northern, Virginia, Washington, D.C., and Maryland who can address any issue with your toilet or other plumbing fixtures.

Letting these problems continue can waste water and increase your bill, literally sending dollars down the drain.

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