Toilet tanks are often the biggest source of water losses in your home - they are notorious for their hidden, silent water waste. Just a small invisible toilet leak (that's one you normally can't hear) will waste from 30 to 500 gallons per day! The ones you can hear will waste much, much more. Many toilets quietly lose gallons each hour and each day, resulting in higher bills for our customers.
Most people will say their toilet does not leak. there is one sure way to find out.
Easy to Follow Instructions
Remove cover from top of toilet tank.
Drop dye tablets (or 2-3 drops of liquid food coloring) into tank and replace cover.
Do not flush the toilet.
Wait 10 minutes.
If colored water appears in the bowl, you have a leak.