Another area that you need to look out for is the water heating element. Over the period of time and due to continuous usage, the element gets a coating of sediment on the surface and this prevents it to heat the water properly. It also consumes more time and thus increases the energy consumption. A professional can change an anode rod if you feel uncomfortable doing it yourself. You also need to flush the tank if you have a storage type water heater to get rid of excessive scaling. If there is too much deposit in the tank, then it will result in rust and it might also make the water contaminated. Do check the water that you are getting from the heater on time to time basis and if you see any particles, then it might be the time to get it flushed.
Always remember to call in the professional to get the water heater checked and serviced. They will make sure that all the points are covered and this will increase the life of your water heater by considerable margin.