· by Michael Blair, Nashville's Plumbing Repair
The sound is easy to recognize once you know it: the fill valve opens for five or ten seconds, then shuts, with nobody near the bathroom. Plumbers call it a phantom flush or ghost flushing. Nothing is flushing. Water is leaking from the tank into the bowl slowly enough that you never see it move, and every so often the float drops far enough to call for a refill. It wastes a surprising amount of water and it is one of the cheaper plumbing problems to fix, provided the right part gets replaced.
Proving where the water is going
Put a few drops of food coloring in the tank, do not flush, and come back in half an hour. Color in the bowl means the flapper or the seat it closes against is letting water through. No color in the bowl but the tank still refilling points at the fill valve or the overflow tube instead, which is a different repair.
Also check the water level in the tank. It should sit below the top of the overflow tube. If it is at or above that line, the fill valve is set too high and water is trickling into the overflow, which drains into the bowl exactly like a leaking flapper does.
The flapper, and why Nashville water wears it out
The flapper is the rubber seal at the bottom of the tank that lifts when you flush and drops to close the outlet. Rubber hardens, warps and picks up mineral deposits, and once it no longer sits flat the seal weeps. Chlorine in municipal water shortens its life, and in-tank cleaning tablets shorten it much more. If you use those blue tablets, stop; they are the most common reason a flapper fails inside a year or two.
Replacement is a few dollars and a few minutes, but it has to be the right flapper. Toilets from different makers, and different eras from the same maker, use different sizes and different chain geometry. Take the old one to the store or match the toilet model number. A universal flapper that almost fits will leak too.
The flush valve seat and the fill valve
If a new flapper does not stop the leak, the seat it rests on is the problem. On older toilets it is part of the flush valve, and mineral scale or a rough edge there will defeat any flapper. Cleaning the seat sometimes works; replacing the flush valve is the reliable fix, and it means lifting the tank off the bowl, which is where most people call a plumber.
A fill valve that will not shut off fully keeps the level creeping up to the overflow. They are also inexpensive, and modern ones adjust for height without tools. A fill valve that hisses constantly, or refills very slowly, is telling you the same thing.
- Dye test first, so you replace the part that is actually leaking
- Set the tank water level about an inch below the overflow tube
- Match the flapper to the toilet, not the shelf
- Turn the supply off at the wall before opening anything
What it is costing you
A slow flapper leak can move a considerable amount of water over a month without a single visible drip, and Metro Water Services bills sewer on the same volume, so the waste is charged twice. A bill that has climbed with no change in habits is worth a dye test in every toilet in the house before assuming anything more serious.
If the toilet is old enough that parts no longer match, or it runs, rocks or needs a second flush, a replacement toilet is often the better spend than a third round of parts. Modern toilets use far less water per flush, and the water saving alone tends to carry the cost over a few years.