Toilet Troubleshooting

Use this troubleshooting page to resolve common problems with a standard, gravity flush toilet.

Toilet is Overflowing ¶ 

Water is freely flowing out of the toilet bowl.

If your toilet is overflowing, the first priority is to prevent flooding and water damage. Open the toilet tank and push down the flapper. This will prevent any more water from filling the bowl. Shut off the water supply to the toilet. Once the water is turned off and you’ve cleaned up the mess, you can troubleshoot the cause of your plumbing problem.

Toilet Flushes but Doesn’t Drain ¶ 

When you pull the handle, the toilet bowl swiftly fills with water but doesn’t drain correctly.

Clogged Toilet ¶ 

The most prevalent cause of a toilet that doesn’t drain is the common clog. Heavy use or foreign material can easily clog a toilet. The quick use of a plunger can usually resolve most small clogs.

Inadequate or Blocked Venting ¶ 

Most waste plumbing requires air pressure to help water and waste move through the drain line and out of the building. Venting in a drain system allows air to apply continual downward pressure through a drain. One sign of a venting problem is the continual rise and fall of the water level in the toilet bowl while it’s not in use.

If venting problems occur soon after a new construction project or recent addition, the problem could be quite simple. Most buildings have venting pipes that run to the roof and allow air pressure to enter the system. During construction, plumbers often cap or cover these pipes while installing the plumbing system. If a vent cap was left in place, it could stop a drain from working properly. If you feel safe climbing on the roof, check for any covered vents and remove them.

Obstruction in the Drain Line ¶ 

It’s possible that the problem with the toilet is actually a problem in the plumbing running from the toilet. Blockages caused by waste, tree roots, or broken drain lines can prevent a toilet from draining correctly. In some cases, a significant blockage in the branch line of a room or the main drain line of a building can cause other drains to work slowly or not at all. Do a quick check on other drains in the room or building. If other drains have begun to perform poorly, this could point to a larger problem with the building’s drain system.

Toilet Doesn’t Flush ¶ 

When the handle is pulled, nothing happens, or the toilet’s familiar flush is replaced by a trickle of water.

Low Water Levels in the Toilet Tank ¶ 

If a toilet tank doesn’t fill properly, the toilet won’t have enough water to flush. Check the water level in your tank. The water should come up to about one inch below the overflow tube. If the water level is too low, double check the water valve to make sure the toilet is receiving water. If this doesn't help, check for problems with the flapper, float, fill valve, and refill tube.

Broken or Disconnected Pull Chain ¶ 

The pull chain connects a toilet’s handle to the flapper. A broken or disconnected pull chain will prevent the flapper from lifting when you try to flush the toilet. Check your toilet tank to make sure that the pull chain is connected correctly.

Loose or Broken Handle or Handle Arm ¶ 

Loose toilet handles are a common cause of flushing problems with toilets, and a broken handle will prevent a toilet from running at all. Loose handles can be tightened easily with an adjustable wrench. If your handle or its arm is broken, use this guide to replace it.

Warped Flapper ¶ 

A warped or damaged flapper can cause extra water to flow into the toilet bowl between flushes. Not only is this a waste of water, it can cause low water levels in the toilet tank and prevent flushing. Look for any visible signs of a warped, bent, or dislodged flapper. Lift up the toilet tank lid and put firm pressure on the flapper. If you notice a change in water levels in the tank or bowl, this is a clear sign of a faulty flapper. Follow this guide to replace it.

Misaligned or Broken Float ¶ 

Problems with your toilet’s float often cause water level and flushing problems. Floats normally look like a round ball attached to an arm or a cylinder wrapped around the tank's main fill tube. The float acts as a cut-off switch, preventing extra water from filling the toilet tank. If a float is stuck or rests too low, it can stop water from filling the tank enough to provide for a proper flush. Check the height of your float; if the float and water level sit more than one inch from the top of the overflow tube, the float should be adjusted. You can adjust the float with the help of this float adjustment guide. If your float won't adjust, or if it fills with water or shows other signs of damage, use this guide to replace it.

Misaligned Refill Tube ¶ 

The refill tube is the small rubber tube running from a toilet's fill valve. This tube is designed to spray water into the overflow tube, and slowly refill the toilet bowl while the tank fills. If the refill tube is pushed down into the overflow tube, it may prevent the tank from filling properly. Make sure that the refill tube is directed into the overflow tube but doesn’t go more than one inch into the tube.

Faulty Fill valve ¶ 

If a toilet tank doesn’t fill properly, the toilet won’t have enough water to flush. Push the float down slightly to see if water moves through the fill valve. If water doesn’t flow into the tank normally, the fill valve may need to be cleaned or replaced.

Toilet Tank is Leaking ¶ 

Water appears to be coming from the toilet tank.

Loose Fill Valve Locknut or Coupling Nut ¶ 

A loose connection from a toilet tank can quickly lead to a minor leak. Check the underside of the toilet tank for wet areas. If the entire underside of the tank is wet, briefly dry it with a towel. Feel around the locknut on the fill valve, where the supply tube connects to the toilet. If water is leaking out around the locknut or coupling nut, tighten it gently.

Failed Supply Tube ¶ 

Supply tubes can sometimes fail, or develop leaks over time. A wet supply tube is a sign of a loose coupling nut or broken supply tube. If water appears along the length of the supply tube, check the underside of the toilet tank around where the supply tube connects to the bottom of the toilet tank. If this area is still dry, your supply tube should probably be replaced.

Loose Tank Bolts ¶ 

Loose tank bolts can cause water to leak around the tank bolts or flush valve seal. Check the underside of the toilet tank for wet areas. If the entire underside of the tank is wet, briefly dry it with a towel. Feel around the tank bolts and around the flush valve, where the toilet tank connects to the bowl. If water appears to be leaking from these areas, gently tighten the tank bolts with a screwdriver.

Loose Flush Valve Shank Nut ¶ 

If water is leaking from around the flush valve, even after tightening the tank bolts, then it’s possible that the large nut that connects the flush valve to the tank is loose. Remove the toilet tank assembly and tighten the large shank nut on the bottom of the flush valve. It is often helpful to replace the flush valve gasket while tightening the shank nut.

Failed Flush Valve Shank Gasket or Flush Valve Seal ¶ 

The seals and gaskets in a toilet can degrade over time. When the flush valve shank gasket or seal begin to fail, water can leak from the flush valve. If these components appear to be failing, remove the toilet tank assembly to replace the shank gasket and valve seal.

Water Leaks From Under the Toilet ¶ 

Water appears to be coming from under the toilet bowl.

Supply Tube or Tank Leak ¶ 

Water forming around the bottom of a toilet may actually be from a leak in the toilet tank. Before removing the entire toilet, check the underside of the toilet tank for wetness. If the underside of the tank is wet, then the leak is likely coming from the fill valve, tank bolts, or flush valve. If the supply tube is wet, it’s likely due to a loose coupling nut or broken supply tube.

Loose Flange Bolts ¶ 

The flange bolts are the large bolts that help to hold a toilet down against the floor. If these bolts are loose, the toilet’s seal can be compromised. If the tank bolts seem loose, dry the area around the base of the toilet and tighten the flange bolts. Be sure to check the toilet again a while after tightening the bolts. Loose flange bolts can often damage the wax ring that seals the bottom of the toilet bowl.

Failed Wax Ring ¶ 

Most toilets have a wax ring that seals the joint between the toilet bowl and the closet flange. If the bottom of the toilet remains wet, even after tightening the flange bolts, then the ring should be replaced.

Toilet is Clogged ¶ 

Something appears to be obstructing the flow of water from the toilet.

Visible Obstruction ¶ 

Oftentimes, obstructions in the toilet are visible and can be removed without the need of equipment or chemicals. For minor waste clogs, use hot water or 2 to 3 cups of bleach to break up the clog without damaging the plumbing. If you choose to use a drain cleaner, be sure to follow the manufacturer's directions to avoid any damage to the drain line.

Unseen Obstruction ¶ 

Unseen obstructions can often be resolved by using use hot water or 2 to 3 cups of bleach to break up the clog without damaging the plumbing. If something is lodged deep in the toilet, use a plunger to clear the obstruction. Flange plungers are recommended for unclogging toilets.

To effectively use a plunger, follow these steps:

  1. Shut off the toilet’s water supply.
  2. Place the plunger into the toilet bowl, making sure the bell of the plunger is completely submerged in water and covers the toilet drain. Add warm water to the toilet bowl if necessary. The bowl should be no more than half full.
  3. Press the plunger down to form a seal over the toilet drain.
  4. Gently plunge up and down a few times while keeping the drain sealed.
  5. Still taking care to keep the drain sealed, start plunging with force. Be patient—sometimes you’ll have to plunge around 20 times to force out the obstruction.

If plunging your toilet doesn’t resolve the problem, try using a toilet auger to clear the clog.

Toilet Runs Continuously ¶ 

Water is continuously flowing from the tank into the toilet bowl.

Tangled Pull Chain ¶ 

If the toilet’s pull chain has become tangled, it can prevent the toilet flapper from closing. Check the pull chain and make sure that has enough slack to allow the flapper to close completely.

Overtightened Handle ¶ 

When the nut on a toilet handle is too tight, the handle arm won’t fall to its resting position after flushing. Make sure the handle has enough play to allow the arm to move freely.

Bent Handle Arm ¶ 

It’s easy to bend a toilet’s handle arm while cleaning the tank or during the course of a repair. If the handle arm moves freely but doesn’t provide enough slack in the pull chain, add slack to the chain or gently bend down the end of handle arm.

Warped or Damaged Toilet Flapper ¶ 

A warped or damaged flapper can cause extra water to flow into the toilet bowl between flushes. Look for any visible signs of a warped, bent, or dislodged flapper. Lift up the toilet tank lid and put firm pressure on the flapper. If you notice a change in water levels in the tank or bowl, this is a clear sign of a faulty flapper. Follow this guide to replace it.

Misaligned or Broken Float ¶ 

Problems with your toilet’s float often cause water level and flushing problems. Floats normally look like a round ball attached to an arm or a cylinder wrapped around the tank's main fill tube. The float acts as a cut-off switch, preventing extra water from filling the toilet tank. If a float is set too high, it will allow water to continually fill the tank and run through the overflow tube. Check the water level in your toilet tank; if the water level reaches the top of the overflow tube, the float should be adjusted. You can adjust the float with the help of this float adjustment guide. If your float won't adjust, or if it fills with water or shows other signs of damage, use this guide to replace it.

One Comment

I must hold down handle to obtain complete flush. Seems that the flapper drops too soon. Any suggestions regarding cause?

Earnest Mercer - Reply

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