Swimming pools and spas are prime leak areas also. That's been the experience of Dick Rennick, founder and CEO of 30-year-old American Leak Detection (Palm Springs, Calif.).

"Pools and spas seem to leak more frequently than anything else," he says. "And a lot of people don't know they leak because they have an automatic pool filler, which constantly keeps the water at a certain level."

There are approximately 1.3 million swimming pools in North America, and the average pool size is from 18,000 gallons to 30,000 gallons. Rennick says that, if a pool loses an inch of water over a 24-hour period, it equates to about 300 gallons.

That's a lot of water.

"An average home with a family of three would really have to work hard to use up 300 gallons of water in 24 hours," he notes.

Ann Belus, co-founder and president of 28-year-old Cable Pipe and Leak Detection, Spring Valley, Calif., sees a pretty even mix of indoor and outdoor leaks in her business.

"The leaks are usually in hot water lines because those pipes are more susceptible to wearing," she says. But the company also does a lot work for condominium and apartment complexes, which run a lot of pipe underground.

This all adds up to higher water bills for homeowners.

"Customers usually call us when they have a high water bill or a high energy bill because their water heater is leaking," Rennick explains. "When the bill isn't $14 a month but $114 a month, then they get concerned."

And most people don't realize how much a small leak will cost them.

"If the leak diameter at 60 psi is 1/4 inch, you can lose 1.2 million gallons of water a quarter, which is a pretty large leak," Belus says. "A smaller leak diameter of 1/32 inch loses 18,500 gallons of water per quarter. That's still a lot of wasted water you're paying for."

Who Do You Call?

"The larger the company, the more diversified they want to become," Rennick notes. "And in that diversification process, they may venture into leak detection."

Smaller companies usually can't afford the high-tech equipment used in modern plumbing leak detection, Belus says. But the most important aspect of leak detection is not the equipment, which can cost a few thousand dollars and that anyone can buy, but the experience and training of the technicians.

"You can't just hire a plumber, give him the equipment, and tell him to do it," she explains. "He has to fully understand everything that's involved in leak detection, from knowing which pipes are underground to what sounds to listen for."

Rennick agrees. "The only thing that can find that leak is the operator. The operator needs good equipment, but the better the operator is trained, the more chance of him or her being able to pinpoint that leak without doing what we call 'bang and bash'."

"Bang and bash" occurs when you can't pinpoint a leak, so you guess and start putting holes in the walls or digging up the yard. This is how it used to be done before the equipment, and the technicians, became more sophisticated.

"This is a very specialized, very narrow niche," Rennick says. "You cannot master it in a few weeks or a few months. The only way to learn it is by doing it, getting in the trenches, making mistakes, and learning from your mistakes."

Piping systems are going to continue to leak, and leak detection services are going to continue to be in demand, he explains.

Belus says her company still uses the small leak detector that she and her husband started with in 1976. Learning the craft, listening to the sounds of the rushing water in underground pipes or through walls, and knowing where that leak is coming from, that's the key to success in the leak detection business, not necessarily the equipment.

"[Our company has] become very proficient at leak locating because that's all our guys do," Belus adds. "You have to know what to listen for, you have to build up the technique that helps you tell exactly where that leak is underground through experience and training."