Did you know you might be flushing hundreds of gallons of water, along with hard-earned cash, right down the drain? A leaky toilet flapper is a very common problem that is often completely undetected by homeowners. To check if you are a victim of flapper leak, simply put dye tablets or food coloring in your toilet tank and walk away for 30 minutes. Be sure that no one flushes the toilet during this time. At the end of 30 minutes, if you see the color in the bowl you have a leak!