There are three likely culprits that can cause a toilet to run continuously — the float, flapper, or fill valve. Luckily, each is easy to replace.

Next, remove the tank lid. Inside you’ll should see the main parts responsible for your toilet's water control: the flapper chain, flapper, overflow tube, a ball float or float cup, and fill valve.

Suppose the toilet’s fill valve is shot. Again, it’s not a big deal. Fill valve kits are designed with DIY installers and handy people in mind. Honestly, there’s not much to installing one.

Reattach the fill tube and push it firmly onto the fill valve. Make sure it perches about 1 in. above the rim of the overflow tube and that the fill tube sends water into the toilet overflow tube.