Hot running water is a luxury that most of us enjoy and expect. We, in fact, take it for granted, until the tap fails to deliver any.

If you're tired of short showers and high utility bills, you can easily take action. A bit of preventive maintenance on the water heater can provide hot water longer, result in energy savings and even extend the life of your water heater.

While some prefer using a plumber, most of what follows can be done by a do-it-yourselfer.

The basics: A water heater has three fundamental parts the enclosure, the water tank assembly, and the burner and control assembly.

The enclosure holds everything together and protects the tank and other fragile parts from damage. There really isn't much you can do to maintain the enclosure, except regular cleaning which improves its appearance. Rust, which may appear from time to time, should be removed using a wire brush, and the affected area should be touched up with a rust-resistant paint.

Since the tank has no inspection ports, it's hard to tell when it's dirty or beginning to rust. Actually, tank rust usually isn't discovered until after a leak occurs. And then it's too late.

Most tanks are made of glass-lined steel. If water gets through imperfections in the glass, you can count on a rusty result, and eventually a leak. A special rod called a cathodic anode (or sacrificial anode) is built into the tank assembly to prevent rust. As long as the rod is in good condition, tank deterioration is drastically reduced.

This is how it works: Water in the tank attacks the rod instead of the tank and after a few years the rod completely deteriorates sacrificing itself for the good of the tank. Once the rod is gone, the water starts working on the tank. To prevent such damage, replace the cathodic anode a $15 item that takes about 30 minutes to install. Cathodic anodes are not readily available in hardware stores; you'll probably have to find a plumbing supply company.

The cathodic anode is about 5 feet long, about three-quarters of an inch in diameter and has a hex bolt welded onto one end. The hex bolt screws into the top of the tank, holding the rod in place inside the tank, and, when tightened down, the nut also makes a watertight seal. CAUTION: Before removing (unscrewing) the rod, make sure to turn the cold water inlet valve off.

While the water is off, and once the rod has been removed, use the open hole to clean and flush the tank. Pour in a citric-acid-based cleaner, wait about 8 hours for the acid to dissolve the minerals at the bottom of the tank, and flush. You'll be amazed at what comes out.

A food-grade, citric-acid-based water-heater cleaning product called Mag-Erad is available at most plumbing-supply stores. Mag-Erad is a one-of-a-kind product, and, thus, can sometimes be hard to find. If this proves to be the case, call its manufacturer, A.O. Smith, (800) 845-1108.

In addition, the burner assembly should be cleaned at least once a year, and more frequent care is even better. Simply brush away cobwebs, dust and other debris that build up. A vacuum with an upholstery brush works well.

Water temperature is another important factor. Water heater manufactures recommend a low water temperature setting whenever possible (130 degrees or less). Modest settings economize on utility bills, extend the service life of the unit and provide safety for the young and the elderly.

At least once a year, the temperature-and-pressure-relief valve should be checked to ensure that it is in good operating condition. The fire service and the plumbing industry recognize this device as the last line of defense against tank ruptures or, at worst, a steam explosion.

And, don't forget the venting system. It should be checked for proper draft and for any visible deterioration. A poor draft condition can be a health hazard or even deadly. A slow or weak draft can damage heating elements, resulting in a reduced service life to the unit.

As consumers, we spend much of our time worrying about when our water heater is going to begin leaking and therefore need replacement. If we maintain our water heaters properly they will last a long time. Also, they will operate more safely and cost effectively. If you want to know more about your water heater and its operation, pick up a copy of the "Water Heater Workbook" by Larry and Suzanne Weingarten.