Look at the water level. If it is constantly draining through the opening at the bottom of the reservoir, the problem is most likely an issue with the flapper. The flapper is the mechanism that is lifted up when the toilet is flushed and closes once the water has drained out of the reservoir to allow it to fill back up for the next flush.
Flush the toilet and watch to see if the flapper closes all the way. If it fails to close all the way, there may be one of several issues causing this.
Disconnect the chain connecting the flapper to the flush handle arm and pull the flapper up to flush the toilet. Lower the flapper until the chain is slack. If the toilet no longer runs, your problem was a chain setting that was too short. Reattaching the chain allowing a little more slack will solve your problem. If this doesn't solve the problem, proceed to the next step.
Flush the toilet once again and feel around the opening at the bottom of the reservoir as well as the rubber seal of the flapper. If there is an obstruction on either one, it would prevent a positive seal and cause your toilet to continue running. Cleaning all obstructions will solve your problem. If this step doesn't solve the problem, proceed to the next step.
Feel around the rubber seal of the flapper for rough sections and cracks. If your flapper has rotted or decayed, it will not get a positive seal. The only solution for a rotten flapper is to buy a replacement. These can be purchased at most hardware stores.
Return the reservoir cover to the toilet once you have completed repairs.
Float shut-off problem
Check the water level. If the water is spilling over into the overflow tube, the shut-off valve is not engaging. There are two types of mechanisms for shutting off the water flow. The first is a float ball, most commonly made of rubber or metal. The other mechanism is known as a Fluidmaster fill valve with a float cup. For float ball repair, see step 2. For Fluidmaster with float cup repair, see step 3.
To adjust the water level down, bend the float arm (the bar attached to the float ball) down slightly. This will cause the float arm to shut off the water refill at a lower level. This will prevent the water from rising above the overflow tube.
To adjust the water level down for the Fluidmaster float cup, squeeze the adjustment clip next to the fill valve and slide the clip down the rod. This will cause the float cup to shut off the fill valve at a lower water level, preventing water from reaching the overflow tube.
Test your adjustments by flushing the toilet until you are satisfied with the results.
Return the reservoir cover to the back of the toilet once repairs are completed.
- If your toilet continues to run after all repairs have been made, you may need to replace the parts in our toilet reservoir. These parts can be purchased in part or in whole at most hardware stores for relatively low cost.