Toilet Leak Test

Toilets can quietly leak from the water holding tank all day long. The flapper (blue item in the bottom of the water tank in the image below) needs to maintain a good seal to prevent this problem. And although the leak might be small, over the course of a day over a gallon of water can be wasted.

Checking for slow leaks can be difficult and a visual inspection will most likely not work in this case. The trick for this test is to use food coloring.

Use a bold color (eg red) to make it easier to see. Place 5+ drops in the toilet water tank.

The coloring should be very apparent. Check the toilet bowl to see if any food coloring has already leaked through the flapper. If this is the case there is a sizable leak and the flapper should be replaced. But most times the leak is too small to see immediately and you need to wait overnight. It is best to do this at the end of the night so nobody accidentally flushes the toilet and you have to start again.

If the toilet bowl has coloring in it the next morning, replace the flapper. Otherwise, you have a good seal and no leaks. The pictures show the difference between a good and bad flapper.