Fix leaky toilets. A "running" toilet can waste two gallons of water per minute. A silent leak can waste up to 7,000 gallons per month. To find silent leaks, put a few drops of food coloring in your toilet tank. Wait a few minutes and look in the bowl. If you see color in the toilet bowl, the tank has a silent leak. Toilet leaks are typically caused by either a worn out flapper valve or a fill valve that doesn't completely shut off when the tank is full. Click on the related link below for a video on how to easily replace a leaky flapper valve.