Swimming pool

Swimming pool

There are nearly 8 million swimming pools in the US [1] and the number is growing, with a 5 to 6 percent year-over-year increase in pool construction annually since 1998.[2]

Swimming pools can use enormous amounts of water and energy. A standard-size pool holds 20,000 gallons of water,[3] and homes with a swimming pool use about 58 percent more water outdoors than homes without one.[4] Water use is relative when speaking of outdoor environments, however. A 675 square-foot swimming pool requires less water than 675 square-feet of turf grass due to the greater amount of water needed to maintain the grass.[5]

Evaporation is the key reason that water is wasted from swimming pools.[6] Without a cover, an average pool of 18-feet by 36-feet loses about 1 inch of water per week in the peak of summer,which adds up to an annual water loss of 7,000 gallons.[7]

Evaporation also uses a huge amount of energy. It takes one Btu (British thermal unit) to raise 1 pound of water one degree, but each pound of 80ºF water that evaporates takes 1,048 Btu of heat out of the pool.[8] It's estimated that the energy costs to heat America's pools and spas run in the billions of dollars annually.[9] During the summer season, a typical backyard California pool, for example, can use enough energy to power an entire home for three months.[10]

The chlorine used in swimming pool cleaning can be harmful to groundwater, to the air into which it evaporates, and to some extent, humans.[11] Chlorine used in swimming pool cleaning is problematic because the amount needed is so high—for example, household bleach contains 5 percent chlorine; chemicals for use in swimming pools can contain from 12 percent to 95 percent chlorine.[12]

Related health issues

Pools have to be kept clean to be used safely, but the chlorine used in many pools and inhaled or absorbed through the skin in large amounts has been reported to have some possible bad effects. The International Agency for Research on Cancer has determined that dioxins, furans, and trihalmenthanes (similar in structure to PCBs) can arise when chlorine comes into contact with organic matter such as leaves and dirt, and can cause a possible increased risk of cancer; possible damage to the liver, kidneys, and the nervous system; and possible increased risk of birth defects.[13][14][1]

A study from Belgium's Catholic University of Louvain found that chlorine could be linked to childhood asthma (in 2-3 percent of cases.)[15] Chlorine may also cause skin and eye irritations and longer-term respiratory problems like “swimmer’s asthma.” The US Environmental Protection Agency (EPA) has reports and recommendations regarding chlorine.[16]


  • outgassing: The slow release of a gas that was trapped or absorbed in material; with materials that contain chemicals, outgassing has lately been considered a possible cause of "sick building" syndrome, where people suffer health effects from the materials around them.
  • Btu (British thermal unit): A unit of energy used universally in the heating and cooling industries. It is defined as the unit of heat required to raise 1 pound of water by 1° F.

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Pool filter question: The energy cost to keep my filter on even 12 hrs a day is astronimical! Anyone know what the min # hrs/day I can keep it on w/out algae build up or other probs?

natural ponds

standard pool filters do require a lot of energy. Our swimming pond designs http://www.aquahabitat.com/swimming.ponds.html are much more efficient, using about the same power as a standard light buld.

The energy figures in the article need a bit of clarification. This is an individual choice, but most pools and swimming ponds that reach 80 degrees F are not going to be heated when they are that warm. While I understand the latent energy of evaporation, the example should have been expressed only for cold weather months, not year around. Again, it depends on location as most temperate climate ponds and pools are not heated during winter.

The evaporation comparison to lawns is also very highly variable. Climate and soil type will drastically affect evaporation, seepage and evapotranspiration in lawns. A lawn can use more water than a pool / pond, but it can also use less.

natural ponds

For those with traditional swimming pools who would like to reduce their chlorine levels, we do offer cost effective alterntives.

For those interested in going to totally natural swimming ponds http://www.aquahabitat.com/ponds/ponds.html
We welcome you to come see photos of what is possible at http://www.tinyurl.com/pondphotos

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