How can I tell if I have a slow, hard-to-detect leak in my toilet?
A common, hard-to-detect leak is caused by a poor seal from the flapper valve at the bottom of the tank. Plum Air recommends an easy check: remove the tank lid, flush, and once the tank refills, add several drops of food coloring to the water. Wait 20 minutes. If any color appears in the toilet bowl, you have a leak that needs professional attention.