[lawgolfer]

Gosh, someone using this board does give good advice (other than myself).

One addition! Replace the "sacrificial anode" on your water heater every 4-5 years. This anode is what protects the metal of the tank against corrosion caused by the small amount of electricity which constantly circulates within water systems. Not one in 500 people even know of this anode, let alone replaces the anode on a regular basis, if ever. The reason why water tanks rust through is because the anode has never been replaced.

The anode is a rod of aluminum or magnesium. Over time it, literally, dissolves (corrodes) away (another reason why you need to drain the tank every year as the sediment settles at the bottom of the tank. Replacement anodes are available at Home Depot or Amazon for around $40.

You can replace the anode yourself. However, you will need a large wrench or, preferably, a socket, and, probably, a "breaker bar" for the socket and a torch to heat the head of the anode as they tend to get stuck in place. The anode will either be a large hex head on the top of the tank around the inlet and outlet pipes or will be integral with the outlet pipe. The latter are particularly hard to remove.

Any time the expansion tank is replaced, so should the anode (believe me, you'll be shocked when you see what remains of the anode--usually only a steel rod around which the aluminum or magnesium was formed).

I've done it myself and learned that I much prefer to have it done by a plumber. It involves a lot of frustration with standing on a ladder, heating the socket head with a torch, and applying a lot of force to break the old anode free from the tank. Anodes which are integral with the outlet pipe are particularly hard to remove as they will be aluminum, not steel, and easily crush and distort. If you do this yourself, the trick is to use an "inside" pipe wrench which drops inside the outlet pipe (a specialized plumbing tool) or insert a 1/2" bolt in the outlet pipe and apply an ordinary pipe wrench to the outside. The 1/2 " bolt prevents the aluminum outlet pipe from being crushed by the application of the pipe wrench.