Step one: the dye test
Take the tank lid off and set it somewhere safe, because porcelain lids crack easily. Drop a few drops of food coloring or a dye tablet into the tank water. Do not flush.
Wait fifteen to twenty minutes, and keep everyone from flushing in that time. If color shows up in the bowl, the leak is inside, from the flapper or fill valve. If the bowl stays clear but you see drips on the floor, the leak is outside the tank, from the supply line, the bolts or the wax ring.
Signs that point to each cause
Match what you see and hear to the likely part.
- Hissing or running water after a flush points to the fill valve
- Color in the bowl after a dye test points to the flapper
- Drips at the base of the tank point to tank bolts or washers
- Wet floor at the wall point to the supply line or shutoff valve
- Rocking toilet with seepage at the base points to the wax ring
- Water pooling only after a flush suggests a cracked tank or bowl
A cracked porcelain tank cannot be repaired reliably, and a hairline crack that weeps only when the tank is full is easy to miss. Replace the tank or the whole toilet. If the floor around the toilet stays damp after you fix the parts above, the water may be coming from a pipe in the slab rather than the fixture, and a leak detection visit can sort that out.
Tank still leaking after a part swap? Call and we will check the rest of the toilet.
Call (855) 575-2890Fix the flapper or the fill valve
- 01Shut off and drain
Turn the oval-handled valve behind the toilet clockwise, flush, and sponge out the remaining water.
- 02Swap the flapper
Unhook it from the overflow pegs, match the new one by size, and set the chain with a little slack.
- 03Replace the fill valve
Disconnect the supply nut under the tank, loosen the locknut, lift the old valve out, and install a new one at the same height.
- 04Refill and retest
Open the valve slowly, adjust the water level a half inch below the overflow tube, and repeat the dye test.
Tank bolts and the seal between tank and bowl
If the drip appears where the tank meets the bowl, the tank bolts or the rubber washers are failing. Tighten the nuts a little at a time, alternating sides, and stop as soon as the leak stops. Porcelain cracks if you overtighten.
If tightening does not help, the washers need replacing. You will drain the tank, remove the bolts, lift the tank off, and replace the gasket and washers. The tank is heavy and slippery, so work with a helper and set it on a towel. Replace the bolts and washers as a set, and use the rubber washer on the inside of the tank, not the outside.
Tavares local note: chlorinated water and rubber parts
The City of Tavares disinfects its groundwater with chlorine, averaging 0.6 ppm in the 2023 report. That level is safe to drink, but chlorine slowly breaks down rubber and soft plastic. Flappers and fill valve seals are often the first parts to go, so replace them when they feel soft, sticky or warped.
Tavares Utilities also publishes no hardness figure. If you see crusty mineral deposits on a flapper seat or fill valve, the water may be leaving scale there. Wipe the seat with a cloth and a little vinegar before you install a new part. For problems beyond the tank, our toilet repair service covers the whole fixture.
When to stop and call a plumber
Call if the supply line or shutoff valve leaks and will not stop with a gentle snug. Call if the toilet rocks, if the floor feels soft near the base, or if you see water coming through a ceiling below. Those signs point to a failed wax ring or a leak that has already spread.
Also call if you have replaced the flapper and fill valve and the dye still reaches the bowl. The flush valve seat may be worn or pitted, and fixing it can mean replacing the whole toilet. A licensed plumber in Eustis or Mount Dora can check it and quote the work, and the same goes in Tavares.
Tools and parts to have ready
You need an adjustable wrench, a bucket, a sponge, a towel, a flashlight, food coloring and a screwdriver. Take a photo of the old part before you go to the store, and write down the brand name stamped inside the tank. Fill valves and flappers come in several sizes, and many shops sell a kit that bundles the flapper, fill valve and bolts, and matching them by photo saves a second trip.
Buy a universal flapper only if the tank is a standard type. Tanks with a wide three-inch flush opening need a larger flapper than the usual two-inch type, and picking the wrong one is a common reason a repair fails. Some low-flow toilets need a specific model, and a mismatched flapper can leak or cut the flush short.
Frequently asked questions
Add dye to the tank and wait fifteen to twenty minutes without flushing. Color in the bowl means water is slipping past the flapper or flush valve seat. You may also hear the toilet refill on its own every so often.
A small leak can lose gallons a day, and a bad one can waste far more. You may not hear it. Your water bill and the toilet running on its own are the usual clues. A toilet that refills by itself in the middle of the night is a strong hint. Fixing a flapper is one of the cheapest repairs to make.
The leak is probably at the wax ring or the closet flange, not the tank. Water at the base after a flush means the seal under the bowl has failed. That repair means lifting the toilet, so call a plumber if you have not done it before.
Close the shutoff valve behind the toilet until the line is replaced. A braided supply line can burst without warning, and a floor leak on a slab can soak flooring fast. Replacement lines are inexpensive and easy to install.
It depends on the part and on the water. Chlorinated water slowly degrades rubber, so many flappers need replacing every few years. Replace sooner if the flapper feels soft, slimy or warped, or if the toilet runs on its own.
No. Epoxy or silicone patches rarely hold under water pressure and the weight of the tank. A cracked tank can fail suddenly. Replace the tank if it is the same model, or the whole toilet, and ask a plumber to confirm the fit.
A licensed plumber can fix it today, with a clear price before work starts.
Call (855) 575-2890Sources and standards
Where this page cites a local fact, it comes from a public City of Tavares page, another city's own web page or a published water quality report. Where a figure is not published, the page says so instead of guessing.
Plumbing work in Florida is governed by the Florida Building Code, Plumbing, which is the standard inspectors apply, and permit rules vary by city. The contact page explains how to reach us, and any plumber's license can be checked with the Verify a License tool at MyFloridaLicense.com.