Not sure why your water bill is suddenly sky-high? There's a strong possibility your toilet may be the problem as it is the biggest water-waster in nearly every home. Here is one fool-proof way for you to test your toilet:
If you look in your toilet bowl and the water seems to be clear and still, you might still have a problem. To test this, simply remove your toilet tank cover and add a few drops of food coloring. If the tank flapper is not sealing correctly, the first place the tank water will go is in the bowl. The food coloring will make it obvious.
Simply replace the flapper and you may have solved your water bill problems.