How Green Is Your Swimming Pool?

It's nice to take a dip in your backyard swimming pool, but your little oasis may come at a tremendous cost to the environment.

Water filters guzzle power, nasty chemicals keep the water sterile, and the water itself is a tremendous waste during dry spells. In fact, this suburban status symbol could be an ecological travesty.

According to USA Swimming and the National Swimming Pool Foundation, there are approximately 10 million swimming pools in the United States. With the average backyard pool topping off at a whopping 25,000 gallons, it's evident that this status symbol is thirsty.

And that thirst is a big problem. In parts of the country suffering from severe drought, such as southern California, farmers and households alike wrestle for their share of this scarce resource.

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San Diego County's main water supplier, the Metropolitan Water District of Southern California, plans to cut back its water deliveries to the city 13 percent this summer.

The San Diego County Water Authority Board will, in turn, cut urban water deliveries by 24 percent, increasing the pressure on everyone to cut back everywhere they can.

The water we jump in and splash around with comes from the same source as our drinking water, so filling up the swimming pool can create an environmental conflict.

The amount of water it takes to operate a pool goes well beyond the initial fill, because the sun and hot weather quickly evaporate a pool's water. The rate at which the water evaporates in a pool varies in different climates and regions around the country.

The evaporation rate is calculated with such a complex formula, Pythagoras himself would have trouble figuring it out. A simple rule of thumb for evaporation is that losing half an inch to an inch per week is normal. But even that amount can be a great strain on the water supply.

One way to decrease evaporation is to put a lid on it -- on the pool, that is.

Many people already have a solar cover, which looks like a giant sheet of bubble wrap floating on the water.

But most of these solar covers go unused, because they're difficult for one person to put on and pull off single-handedly. Imagine trying to fold a giant, wet blanket.

Still, the benefits of using the cover most certainly outweigh the extra effort, because a cover can reduce the amount of make-up water needed by 30 to 50 percent, according to the U.S. Department of Energy.

Evaporating water typically goes unnoticed by most swimmers, but the red eyes, bleached bathing suits and strong chemical smells of many suburban pools always get attention. They're the result of simply keeping the water clean.

"The entire function of the chemicals in pools is to keep them sanitary and pleasant to look at," explains Dr. Neal Langerman, member of the American Chemical Society.

Any body of water, including a swimming pool, is a breeding ground for bacteria, algae, insect larvae and viruses. A pool needs to be sanitized to prevent the growth of these threats, which is done with a sanitizer most people refer to as "chlorine."

"The traditional sanitizer found in a swimming pool is a concentrated form of household bleach called sodium hypochlorite," Langerman explains. "Depending on your local climate, an algaecide may also be needed."

Traditionally, swimming-pool chlorine comes in pucks or tablets that can be tossed in the pool's skimmer or filtration system. As they dissolve, they sanitize the water.

"The puck or tablets have a high concentration and are toxic. But once they are diluted in the pool water, it's no more harmful than the water in your shower. The real concern is when this sanitizer reacts with organic material," says Dr. Thomas Lachocki, CEO of the National Swimming Pool Foundation. "This reaction creates disinfection byproducts, and some of these are carcinogenic."

Exposure to the chemicals and byproducts over the course of decades has been reported to increase risks of cancer and other respiratory ailments.

A study presented at the 51st Annual Meeting of the American College of Sports Medicine (ACSM) showed that swimmers with just several minutes swimming in water with chlorine had an incidence rate of over 60 percent for exercise-induced bronchoconstriction (EIB) -- basically, an asthma attack without the asthma.

The study showed that the most commonly recommended concentration of chlorine -- one part per million -- in a pool increased the rate of EIB by over 60 percent.

When the chlorine was cut by half, to 0.5 PPM or less, the EIB risk rate dipped to under 20 percent. That makes it evident that reducing the amount of chemicals may reduce harmful risks and respiratory ailments.

According to Lachocki, the "smell" that burns your eyes and nose at indoor pools consists of chloramine vapors, which are produced when chlorine reacts with organic material floating in water.

"Proper ventilation of indoor facilities virtually eliminates these chloramines and that strong chemical smell," he says.

As the harmful effects of chemical disinfection on a swimmer's health become better understood, environmentalists worry that these chemicals have damaging effects on the environment.

"When you keep proper pool chemistry, follow the labels exactly as they read, and put the correct amount of chemicals in the pool," says Lachocki. "It will not adversely impact the environment. Most people discharge their pools into the storm drains -- the chemicals are not stable enough to worry about, they rapidly break down and leave a solution of salt water."

Still, people worry about the dangers in using and handling these chemicals altogether, so healthier and more eco-friendly alternatives are being developed as swimmers go green.

One alternative is salt. New technologies have been developed so that the pool boy can use salt as a sanitizer and limit his exposure to harmful chemicals.

"It's such a better way of sanitizing a pool. Our salt chlorine generator uses low levels of voltage to create electrolysis and convert salt into liquid chlorine as the pool water passes through the cell," explains Bill Kent, owner of AquaCal AutoPilot, Inc., in St. Petersburg, Fla. (www.autopilot.com). "After the process, there's less salt in the pool water than in a human tear -- it is below the taste threshold."

"Plus, during the electrolysis process the disinfectant byproducts are burned up reducing the risk of respiratory ailments and cancer," adds Kent.

These salt chlorine generators are relatively inexpensive and can fit most existing pool filtering systems.

"About 99 percent of all the new pools we install include a salt chlorine generator," noted David Pew, service manager and construction supervisor at Backyard Oasis Pools, Inc. in Wake Forest, N.C. "The units can be retrofitted for just about any existing pool for anywhere from $1,200 to $2,000, depending on the size of your pool, without draining the water."

The savings make a big splash because salt is much cheaper than chlorine.

Other technologies becoming very popular are ultraviolet-light and ozone-based filtration systems. Both are a bit more expensive, but show promise in reducing and even eliminating the chemicals needed to keep the pool water clean.

For many environmentalists and scientists, it's not the chemicals drowning the potential for a pool to be green -- it's the filter. Of all household appliances, pool filters are the largest energy consumers after air conditioners.

One way to reduce a filter's energy consumption is to replace the old power hog with a new, more efficient, variable-speed unit.

A study by the Center for Energy Conservation at Florida Atlantic University showed that some pool owners saved a whopping 75 percent of their pool's energy consumption by replacing pumps and reducing the amount of time their filters were run.

Cash-strapped owners who can't afford to replace pumps can still find themselves swimming in a 60 percent energy savings simply by cutting back on filter running time.

Despite all the strides toward more efficient pools and the advances in chemical reduction, there are many environmentalists who feel that swimming pools are an inessential luxury item outright.

"Swimming pools are an environmental insult and should not be put in back yards," says Langerman. "The pool people will hate me, but I don't care. The impact is so severe it simply doesn't make sense."

Whether or not you agree, it's extremely unlikely that anyone is going to backfill their pools with dirt this summer. This suburban status symbol is not going away, but least it's getting a little bit greener ... and not necessarily due to algae.