After reading the tap dripping post I just had to ask. I work in energy conservation and it is amazing how much a leaky toilet can cost in water usage! I had a Doctor's office call and complain it turned out that he had 4 toilets and all of them were leaking (the water constantly running from the tank into the bowl) I t cost him roughly $ 400 one month for this.
The toilet leaks due to the flapper in the back not closing tightly on the opening to the bowl. It take minutes to fix and costs less then $10.00 well worth the effort!