Toilet repair and installation

Almost always the flapper. It is a rubber seal at the bottom of the tank that hardens and warps with age, letting water seep into the bowl until the fill valve senses a low level and tops up. Test it by putting food colouring in the tank and not flushing: if colour appears in the bowl within twenty minutes, replace the flapper. If the flapper is new and it still runs, the fill valve or the flapper seat is the culprit.

Commonly 100 to 300 gallons a day, and a badly seated flapper can waste far more. It runs silently and continuously, which is why the first sign is often a water bill that has doubled with no change in habits. This is the single cheapest repair in plumbing with the largest ongoing cost for ignoring it.

Yes. Movement flexes and breaks the wax seal between the toilet and the drain flange, and once that seal is broken every flush puts a small amount of waste water into the subfloor. It rots the floor from below and lets sewer gas into the room. Sometimes it is just loose bolts; often it is a damaged flange or a subfloor that has already begun to soften. Do not just shim it and hope.

Repair if the toilet flushes well and the porcelain is sound. Parts are cheap and standardised, and a well-made older toilet can be rebuilt for under $250. Replace if the bowl or tank is cracked, if it is a first-generation 1.6-gallon model from the early 1990s that clogs constantly, if the trapway has scaled up, or if you are on your third repair visit in two years.

Either the design or the trapway. First-generation low-flush toilets from the 1990s are notorious for it. Otherwise, look for a partial obstruction lodged in the trapway or hard water scale narrowing it invisibly from inside. If a plumber has augered it more than once and it clogs again, the toilet itself is the problem and replacing it is cheaper than continuing to clear it.

Three candidates. A failed wax ring, which puts waste water on the floor with each flush. A leaking supply connection or shutoff, which puts clean water there continuously. Or condensation on the tank in humid weather, which is harmless but looks alarming. Dry it thoroughly, then flush and watch: water appearing during the flush is the seal; water present all the time is the supply.

If the current toilet is a pre-1994 unit using 3.5 gallons or more, yes. A modern 1.28-gallon toilet saves a family of four roughly 10,000 to 13,000 gallons a year and flushes better than the unit it replaces. Do not confuse modern low-flow with the poor first-generation 1.6-gallon models; the engineering changed substantially and the good ones clear a MaP test at 800 grams or above.

A comfort-height (or right-height) bowl puts the seat at roughly 17 to 19 inches instead of the traditional 14 to 15, similar to a dining chair. It is easier to sit down onto and stand up from, which matters for tall adults, older people and anyone with knee or hip problems. It costs little or nothing extra when you are replacing anyway, and it is the change people mention to us most often afterwards.

It is one of the more approachable plumbing jobs, and many people do it successfully. The parts that go wrong are the parts you cannot see beforehand: a corroded flange, a soft subfloor, a rough-in measurement that does not match the new unit, and over-tightened bolts that crack the porcelain. If the old toilet was rocking or leaking, have someone look at the flange before you buy a replacement.

Yes, and they are the most common cause of avoidable blockages we see. They pass the toilet fine and then fail to break down, catching on joints, roots and any irregularity in the line, then collecting everything that follows. The same applies to paper towel, tissues and cotton buds. Nothing but toilet paper and human waste should go down a toilet, regardless of the packaging claim.