Discolored vinyl flooring near or under a toilet is unsightly, but it can also indicate a problem, such as a leaking toilet. Not all leaking fixtures leave puddles on the floor. Sometimes a leaking toilet can damage floor coverings and underflooring without creating any obvious signs. Detecting and stopping leaks early helps prevent rot and costly water damage.
Discoloration from toilet leaks doesn't always take the form of a water ring immediately next to the fixture. It can also look like a colored stain and appear some distance from the toilet. These less obvious stains are caused by small amounts of water seeping through the floor material. While this type of stain can be small and unobtrusive, it still requires attention since a slow leak can seriously degrade subflooring and wooden structural supports.
If the toilet wobbles or moves from side to side, it probably also leaks. A loose toilet has poor contact with its wax seal and will allow water to leave the fixture over time. Tightening the nuts on either side of the toilet can sometimes fix the problem temporarily but can also damage the fixture itself. If the seal has become deformed or broken, tightening the toilet won't help, and the seal needs to be replaced entirely.
Installing a new wax seal is a simple process but does require some care. Shut off all water to the toilet, and drain the tank and bowl before removing the fixture to prevent further leakage. Scrape the old wax ring off the floor, inspect the toilet flange for damage and place the new ring. Set the toilet back onto the ring in one vertical motion. Allowing the toilet to rock or move off center can destroy the ring, causing an imperfect seal. If you're not certain of your ability to replace the toilet correctly, have the new seal installed by an experienced plumber.
Not all flooring stains are caused by toilet leaks. According to Ask Tool Talk, high moisture concentrations can cause a chemical reaction between minerals in a concrete subfloor and the glue used to secure the vinyl. This type of problem often gets worse after a shower or after mopping the floor. These stains are merely cosmetic and do not indicate a leak. However, differentiating this type of stain from one caused by a leak without inspecting the toilet seal is difficult.