"Old reliable" churns away in your basement or utility room day after day, month after month, year after year like a farm mule in days of yore. Except this one doesn't eat as much - nor do you have those ugly, malodorous piles laying all around the place!

Except every once in awhile, like a cantankerous old mule, the modern water heater doesn't do what it's supposed to do. That's when you call a plumbing contractor saying "no hot water."

This is the top reason why people call a plumbing or heating contractor, according to a survey taken a few years ago by the Plumbing-Heating-Cooling Information Bureau (PHCIB) in Chicago. A related problem, a leaking water heater, came in at number 5 out of the top 10.

Looking over the list, I can't help but shake my head at all the waste of time and money these emergency service calls represent. Most people don't pay much attention to their household "mule team" - the mechanical systems that provide so much comfort and convenience in our modern lives. We take for granted our water heaters, toilets, faucets, furnaces and air conditioners, until they stop working. Then comes the panicked call to the service company, and a repair job that always ends up costing more than we expect.

Regular care and maintenance can forestall most of these breakdowns at a fraction of the cost of repairs. Have your plumbing, heating and air conditioning inspected, cleaned and checked at least once a year. Progressive service companies offer service agreements in which they automatically come out to take care of these things for a modest annual fee.

Homeowners also should consider replacing ancient water heaters, toilets, furnaces, boilers and other appliances with new high-efficiency or water-saving models. Most of us are in the habit of squeezing out every last day of service out of such equipment. Yet any unit more than 12-15 years old probably can pay for itself within a few years through reduced energy or water usage.

Here are the rest of the top 10 household repairs identified by the PHCIB.

#2 - Clogged drains. Many of these calls could be avoided by taking greater care in what you put down drains - especially the kitchen sink drain, the most used and most clogged drain in the house. I also recommend regular treatment with Bio-Clean, a biological drain cleaner sold only through plumbing contractors.

#3 - Dripping faucets. This is an annoyance that most homeowners have to deal with from time to time as the washers in the faucets wear out with use. You can extend the life of your faucet washers by not turning them off with too much force.

You may also consider replacing your older faucets with those that feature washerless valve cartridges instead of rubber washers. Since the valve mechanism is contained in one cartridge, these faucets are easier to repair and replace. In addition, cartridges are generally more durable and do not leak because they do not deteriorate with friction or age as washers do.

#4 - Leaking pipes. In extreme cases, these can cause expensive damage to floors and belongings. To stop a small leak from turning into a big one, take a look at your pipes periodically to check for rust or white lime deposits that may indicate a leak is starting.

#5 - Leaking water heaters. Most often when you have a leaker, it's time to get rid of the water heater. Usually leaks indicate rusting through at the bottom of the storage tank, for which there is no good repair. By the time this happens, the water heater is usually so old you'd benefit from replacing it with a more energy-efficient model anyway.

#6 - No heat. When your furnace or boiler stops operating, it can make for a long, cold winter night. An ounce of prevention here is worth of ton of cure. It's important to make sure your heating system is functioning properly before the first cold snap hits. Have a competent contractor do a thorough examination and cleaning in late summer or early fall every year.

#7-8 - Running & leaking toilets. This is not only an annoyance, but a waste of water and money. Leaky toilets can cost you upwards of $100 a year on your water bills. If you hear a low humming noise, or if the toilet continues to run into the bowl after the toilet is flushed, it indicates that some part of the mechanism is out of order. Sometimes a little jiggling of the ballcock or flush valve mechanism solves the problem with cost. Otherwise you may need to replace the entire mechanism.

#9 - New faucet installation. Many homeowners replace faucets not only when they break down, but for decorative reasons as well. This is the ninth most common reason for a service call, according to the PHCIB.

A few people buy a faucet from a home center and then call a plumbing firm to do the installation. This is okay, but be forewarned that in doing so, the plumbing firm will warrant only its workmanship, not the faucet itself.

#10 - Malfunctioning food waste disposer. This can be a messy headache for homeowners. Here are several tips to keep your unit in good working order. First, always run cold water when grinding to move the waste all the way down the drain lines. Fats and grease congeal and harden in cold water and can be flushed through the system. Hot water should not be used because it can dissolve fats and grease, which may then accumulate in the drain line.

Almost all bio-degradable food waste can be fed into disposers. However, they should not be used to grind clam or oyster shells, corn husks or other material with a high fiber content. Under no circumstances should you put glass, plastic or metal non-food materials through a disposer. This includes bottle caps, tin covers or aluminum foil, which are some of the items service technicians commonly find in clogged or broken disposers.

Maintenance is easy. Grinding small bones and egg shells actually helps clean the disposer by scraping away stubborn deposits or citric acid and pulp. Grinding a little ice is another way to clean deposits and get rid of odors. For the most part, though, disposers are self-cleaning.