If the numbers of gallons of water that you use each month has increased without reason it could be something as simple as a leaking plumbing fixture or sprinkler head. It could also be traced to an underground water pipe that has begun to leak. Because these under "slab leaks" can eventually lead to damage to the foundation of your home or apartment any suspicion of a slab leak should be investigated.
There are several different options for a homeowner that is tired of watching cold water run down the drain while waiting for hot water to arrive each morning. There are retro fit systems that can be installed which will allow the recirculation of hot water between the hot water tank and the far end of the home.
Definitely, and if you are to busy to meet me at the property I'll be glad to call you with a diagnosis and several different options for repair.
It is common for older water heaters to become so full of collected sediment that it reduces the amount of water that can be heated in the tank. If your water heater is more then ten years old it would be best to consider replacing the hot water heater