How to Fix a Low Flow Toilet

plunger in a toilet bowl
  • 1 hours
  • Intermediate
  • 0-40
What You'll Need
Needle nose pliers
Flapper valve
What You'll Need
Needle nose pliers
Flapper valve

Failure for waste to clear your toilet is a common problem as a result of a low flow toilet. You will notice that the flush is slow, and everything does not go down. Then you have to wait until the tank is filled and flush it again. It can be gross and frustrating. A low flow toilet is usually caused by the handle linkage being too long or a warped flapper valve that can easily be fixed.

Step 1 - Open Toilet

Lift the back of the toilet and set it where it won't fall and break. Straddle the toilet and look inside. You will see many simple parts. On the bottom there is the flapper valve and attached to it is a chain. The problem is the chain or flapper valve.

Step 2 - Check the Chain

inside a toilet tank

First check the chain. The chain is attached to the flush arm. The flush arm is attached to the handle you use to flush the toilet from the outside. When the handle is pushed down, the flush arm is lifted. The chain attached to the flush arm is pulled up, opening the flapper valve. The chain needs some slack so it can be pulled up by the arm. It should not have more than one inch of slack.

Step 3 - Adjust the Chain

Flush the toilet while watching. If there is too much slack on the chain when flushed and the flapper valve does not lift quickly, adjust the chain at the flush arm end. For most chains you can simply take one of the links and hook it on the metal hook that attaches the chain to the flush arm. If not, you may need needle nose pliers to open one of the chain links and attach it to the flush arm. Try flushing the toilet and see if the problem is fixed. If not, continue reading.

Step 4 - Check Flapper Valve

black toilet flapper valve

The other problem that may cause a slow flow toilet is the flapper valve. The valve could be warped and unable to create a tight seal. To replace the flapper valve you will need to turn off the water flow to your toilet. The water valve is located in the back of the toilet, at the bottom, near the wall.

Lift the flapper valve and look at the bottom. If the bottom circle of rubber is warped (not completely round) then it needs to be replaced. You can remove the flapper valve along with the chain. Unhook the chain at the end where the flush arm is. Take the flapper valve with you to the hardware or plumbing supply store. Buy a replacement valve and bring it home.

Step 5 - Replace Flapper Valve

Replacing the valve is as easy as it was to remove. Place the valve on the hole and then hook the chain to the flush arm. Adjust the chain if necessary so there is not too much slack. Make sure the flapper valve is on the hole properly. Turn the water flow to the toilet back on. Test your flush.