Why Toilets Flushing Slowly and often Incompletely

How to Fix Sluggish Toilets

By Mark J. Donovan




If you have one or more toilets flushing slowly or not completely you may very well have a systemic problem somewhere in your home’s waste/vent sewer pipes. It is important to understand that there are three key ingredients necessary for a toilet to flush properly. For toilets to flush completely and properly they need (1) sufficient water running through them, (2) adequate air venting to allow the flushed material to keep moving during the flush, and (3) no blockages to hamper the movement of the water, waste and air through the toilet. Failure to deliver on any one of these three ingredients and a toilet will not flush properly.

If you have a toilet, or toilets, flushing slowly and incompletely then you need to troubleshoot, diagnose and solve the problem following the steps listed below.

First, use a plunger to remove any potential blockages in the waste line of the toilet. Make sure you use a plunger that can make an effective seal with the toilet bowl. Also make sure the plunger is fully submerged in the toilet bowl water when plunging to ensure a strong enough plunge of air into the toilet bowl outlet. This process should loosen any blockage and allow the water and waste to begin moving freely again through the toilet and waste pipe.

Second, turn water off to the toilet tank and then flush it. Using rubber gloves feel for any obstructions in the toilet P-trap. Also check in the toilet inlet for any debris that could be clogging the toilet. Then again turn water back on to the toilet tank.

Third, remove the toilet tank cover and check the water level in the tank. The water line in the tank should be such that it is sitting about one inch or less from the top of the overflow tube.

Why Toilets Flushing Slowly and often Incompletely

If it is lower than that then the toilet may not be getting enough water to fill the waste pipe and to create enough suction when you flush the toilet. If necessary adjust the screw on the float ball assembly so to adjust the standing water level in the tank.

Four, when flushing the toilet listen for any gurgling sounds coming from other nearby drains, e.g. the bathroom sink drain as well as other nearby sinks. If you hear gurgling sounds, then this is an indication that the toilet vents are blocked.

You will need to get up on your home’s roof and clear the vent stack pipe. There may be leaves, sticks, or pine needles clogging the vent stack pipe. Run a garden hose down the pipe and spray water down the vent stack pipe. This should hopefully clear any clogs in the vent stack pipe.

Five, using a straighten paper clip poke the water inlet holes around the inside rim of the toilet bowl to clear any mineral deposits that may be clogging them. The mineral deposits can impeded water flow into the toilet when you flush the toilet, which ultimately prevents the formation of adequate suction required for proper flushing.

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You will need to get up on your home’s roof and clear the vent stack pipe. There may be leaves, sticks, or pine needles clogging the vent stack pipe. Run a garden hose down the pipe and spray water down the vent stack pipe. This should hopefully clear any clogs in the vent stack pipe.

Five, using a straighten paper clip poke the water inlet holes around the inside rim of the toilet bowl to clear any mineral deposits that may be clogging them. The mineral deposits can impeded water flow into the toilet when you flush the toilet, which ultimately prevents the formation of adequate suction required for proper flushing.

Six, use a toilet auger to clear the waste lines after you’ve done all of the above and still have no success. Insert and feed the auger line into the toilet bowl until you encounter resistance. Then crank the auger handle to work the auger head through the blockage.


Lastly, run a sewer auger down the roof vent stack to clear out any obstructions that the water hose may have failed to remove. Again, when an obstruction is felt, crank the auger handle until resistance is eliminated.

By following these seven steps you should be able to resolve your home’s toilet woes.


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