If your water bill seems high, it may be a leak in your toilet.  Toilet  leaks are the most common leaks.  They usually occur in the overflow  pipe or plunger ball.  Check your toilets and faucets for leaks twice a  year. 

Your  water meter is usually located in your basement where the water supply  enters your home.  The shut-off valve is usually located here too.  It  is important to know where the master shut-off valve is in case you have  a major leak.

The meter is read by a radio transponder.  The transponder is  integrated into the water meter.  The meter reader just needs to drive  by your house and the reading equipment automatically picks up the  reading.

Put a  couple of drops of food coloring into the back tank of your toilet (do  not flush).  If any of the coloring comes through to the bowl, then  there is a leak.  Usually it is the rubber ring by the plunger that can  easily be replaced for a few dollars.

Another way to check is to read the water meter in your basement  before going to bed and then again when you wake up in the morning.  As  long as you know no one has used water, the meter dials will  not move.  If they have moved, then something has pulled water through  the meter which could be a leak.