How to Fix a Free-Flowing Toilet

5. Check the Flapper

A Flapper can become dirty, brittle, or warped, meaning it no longer creates a proper seal and allows water to run freely into the toilet bowl. To remove the flapper, unhook the sides from pins at the base of the overflow tube. If there are mineral deposits or dirt on the flapper, place it in vinegar for 30 minutes before brushing off any dirt with an old toothbrush. If your flapper’s showing signs of wear and tear, you will need to buy a new one. Take the old one to the store to ensure you get one in the same style and follow the instructions on the package to install it.