A toilet that keeps running is not an emergency, which is exactly why it runs for six months. It is also quietly expensive: a constantly cycling toilet can waste a couple of hundred gallons a day, and you will meet that on your water bill long before you get annoyed enough to fix it.
The good news is that the fix is almost always a ten dollar part, and there are only three real candidates. Here they are in order of how likely they are and how little they cost.
First, find out which kind of running it is
Take the lid off the tank and put it somewhere it will not get stepped on. Then watch for a minute.
If water is trickling into the bowl and the tank keeps refilling to make up for it, the leak is at the bottom of the tank. That is the flapper. This is the common one by a wide margin.
If water is running into the overflow tube (the open vertical pipe in the middle of the tank), the tank is filling too high and spilling. That is the fill valve or its float setting.
If it runs for a few seconds every so often with nobody in the room, that is a slow flapper leak. Same fix as the first case, just a smaller version of it.
Fix one: the flapper
The flapper is the rubber disc at the bottom of the tank that lifts when you flush and drops to seal afterward. Rubber hardens, minerals build up on the seat, and eventually it stops sealing.
The confirmation test takes ten minutes and costs nothing: put a few drops of food colouring in the tank and do not flush. Come back in fifteen minutes. If there is colour in the bowl, the flapper is leaking, full stop.
Replacements are ten to fifteen dollars at any hardware store. Shut off the supply at the valve behind the toilet, flush to empty the tank, unclip the old flapper from the pegs, note where the chain sits, and clip the new one on. While you are in there, run a finger around the seat the flapper lands on. If it feels rough or crusty, wipe it clean, because a new flapper on a rough seat leaks too.
One more thing to check first, because it costs nothing: the chain. Too short and it holds the flapper open a hair. Too long and it slips under the flapper and props it up. You want just a little slack.
Fix two: the fill valve
If water is pouring into the overflow tube, the tank is filling past where it should stop.
Try the float adjustment first, because it is free. Modern fill valves have a clip or a screw on the float that sets the shutoff height. You want the water line about an inch below the top of the overflow tube. Move it down, flush, watch it refill, adjust again.
If adjusting does nothing, or the valve hisses, or it never quite shuts off, the valve is worn. A universal fill valve is around twenty dollars and swaps out in about twenty minutes with the water off and the tank empty.
Fix three: the flush valve or the whole works
If you have replaced the flapper and it still leaks, the flush valve seat itself may be pitted or warped. On an older toilet, this is the point where replacing the entire tank assembly (fill valve, flush valve and flapper as one kit) makes more sense than a third trip to the store for a fourth part.
That job means pulling the tank off the bowl, which is more than most people want on a weeknight, and it is a fine thing to hand to a plumber.
When it is not the toilet at all
A few running toilets are a symptom of something upstream.
If several toilets in the house misbehave at once, or if fixtures bang and hiss generally, check your water pressure. Pressure over about 80 psi chews through fill valves, supply lines and appliance hoses, and it is a house-wide problem worth solving once rather than replacing parts forever. Here is how to check it.
If the toilet also drains slowly or gurgles, you are looking at a drain problem wearing a toilet costume, and the toilet parts are innocent. Work out whether it is that fixture or your main line first.
If the tank sweats and puddles on the floor, that is condensation rather than a leak, and it is a different conversation.
The tablets thing
Skip the in-tank cleaning tablets, especially the bleach ones. They sit against the flapper and the seals all day and shorten the life of every rubber part in the tank. Plenty of the “my new flapper failed in six months” stories start with a tablet in the tank.
When to call somebody
Call if the shutoff valve behind the toilet will not turn or will not seal, if the tank is cracked, if the toilet rocks on the floor or the base is wet (that is the wax ring, and water is going under the floor), or if you have done the flapper and the fill valve and it still runs.
SwiftPro handles toilets, and everything else plumbing, across Northern Virginia. Call (703) 997-9757 or book online. If the answer is a ten dollar flapper you can fit yourself, we will tell you that too.
