Swimming Pool and Spa Introduction

Swimming Pool

A swimming pool is an artificially enclosed body of water intended for recreational or competitive swimming, diving, or for other bathing activities that involve swimming, e.g. play, wading, water exercise, floating on inflatable toys, cooling off on hot days, or just sitting and entertaining around. The chemical chlorine is most commonly used as a sanitizer, primarily to control algae, bacteria and pathogens.  Alternative pool systems use saltwater or UV treatment systems to maintain sanitation. Swimming pools can be constructed either above ground (generally constructed from plastic and metal), or in the ground (usually formed either out of reinforcing steel bars concrete and lined with sprayed or pumped concrete, prefabricated sectional walls and a vinyl lined interior), or a one piece fiberglass shell.[1] 

Hot Tub/Spa

A spa or hot tub is a large manufactured tub or small pool full of heated water and used for soaking, relaxation, massage,Jacuzzi or hydrotherapy. In most cases, they have jets for massage purposes.

There are two different styles of hot tubs:

  • Simple wooden-staved soaking tubs
  • One piece plastic tubs (usually referred to as "spas")

Hot tubs are usually heated using an electric or natural gas heater, though there are also submersible wood-fired heaters, as well as solar hot water systems. Water sanitization is very important in hot tubs, as many organisms thrive in a warm, wet environment. Maintaining the hot tub water chemistry is also necessary for proper sanitization and to prevent damage to the hot tub.[2] 

Water Use

The amount of water used to fill and maintain a swimming pool throughout the year is affected by a variety of factors including:

  • Size of the pool (surface area and depth)
  • Amount of evaporation (related to local climate)
  • Frequency of backwashing
  • Leakage
  • Frequency and method of pool and pool deck cleaning
  • Splashing
  • Presence and use of a pool cover 
  • Temperature of pool water (warmer water evaporates more easily)
  • Presence of a fountain or waterfall
  • pH and chemical content of pool water
  • Individual maintenance habits

Because of the variability of conditions listed above it is difficult to determine how much water a swimming pool will use. By comparing homes with and without swimming pools and correcting for differences in landscape size its estimated that homes with a swimming pool use about 58 percent more water outdoors than homes without a swimming pool (Maddaus and Mayer, 2001). This research indicates that the addition of a swimming pool results in a substantial increase in water use.

Water Saving Tips

A few simple methods can save precious water in and around your pool

  • Use a pool cover. It will reduce water loss due to normal evaporation. The cover can also reduce heating bills by preventing night heat loss and will save on chemicals too. Pool covers come in a wide range of types and costs. Consult your pool service company, builder or pool retail store. Make certain that it fits properly. The cover is the number one water and energy conservation device!
  • Repair any swimming pool leaks. Even a small leak in either pool equipment or the pool's structure represents a substantial waste. In fact, an inch-a-day leak in a 15-by-30-foot (4.6-by-9.1 m) pool can waste approximately 102,000 gallons per year (386 m3)!
  • If heated, reduce your pool and spa water temperature to save water and energy costs. Warmer water evaporates more quickly.
  • Shut down unnecessary fountains and waterfalls. The effect of aeration loses a significant amount of water to evaporation.
  • Manually clean your filter. You'll do a more thorough job and use less water. The average backwash uses between 250 to 1,000 gallons (.95 m3 to 3.78 m3) of water -- without completely cleaning your filter!
  • Curb diving, splashing and water fights in your pool and spa. Boisterous play causes inordinate amounts of water loss due to splash-out.
  • Maintain proper chemical levels and adequate circulation time. Not only will your pool water be safer and cleaner, but you'll avoid the need to drain your pool or use excessive water to correct conditions of neglect.
  • When you are filling your pool, be sure to keep an eye on your water level. Forgetting to shut off fill water can make for a costly waste of water.
  • Plug the overflow line when the pool is in use and always when adding water. Keep the pool water in the pool.
  • Turn off the tile-spray device on your automatic pool cleaner. Its splashing invites evaporation losses, and overspraying can send water right out of the pool! A good deal of that spray evaporates before it hits the tile.
  • Reevaluate the frequency of backwashing if your pool has no separation tank. Most people backwash more frequently than necessary. This wastes water. Some pool filters do not have to be backwashed at all; they can be taken apart and cleaned, even though this process is less convenient.

For information on using solar energy to heat your pool and save energy click here for an excellent article from Home Energy Magazine.

www.epoolandspa.com (accessed 6/28/01) Permission granted.

Drought Action

In a severe drought you may be restricted from adding any water to your swimming pool, backwashing, etc. This may effectively shutdown your pool for the year. The bad news is the swimming season is over. Consult your pool specialist before removing water from your pool, as some pools require a certain amount of water to maintain structural integrity. The good news is that you can use the water in your pool to water your plants! Allow the chlorine level in your pool to drop to a level that won’t damage your plants. Use a siphon hose or buckets to distribute water across you landscape. Keep using your pool cover to prevent evaporation.

Energy Savings

Swimming pools and spas use energy to heat water, to run filtration systems, to pump water into the pool and through Swimming Pool Coverwater features, and for lighting. You can reduce the energy consumed by your swimming pool by implementing the following recommendations:

  • Use a pool cover. It will reduce heating bills by preventing night heat loss and will save on chemicals too. Some pool covers are designed to use solar energy to heat the pool. Make certain that the cover fits properly. A cover is the number one fossil fuel conservation device!
  • If heated, reduce your pool and/or spa water temperature. Some pool covers are designed to use solar energy to heat the pool.
  • Shut down unnecessary fountains and waterfalls to reduce pumping costs.
  • Manually clean your filter. You'll do a more thorough job and use less energy.
  • Reevaluate the frequency of backwashing if your pool has no separation tank. Most people backwash more frequently than necessary. This wastes water and energy. Some pool filters do not have to be backwashed at all; they can be taken apart and cleaned, even though this process is less convenient.
  • Install a solar water heating system for your swimming pool.

Your savings will vary depending upon your specific swimming pool and situation, but by implementing a few simple efficiency measures it should be possible to save a substantial amount of energy in your swimming pool.

It is estimated that the energy costs to heat the nation's 5.7 million pools and spas run in the billions of dollars annually. Outdoor pools use high amounts of energy to heat water, which loses heat during the evening and through evaporation. Indoor pools use a lot of energy for systems that remove evaporation-caused humidity.

pool cover can dramatically reduce energy use by a swimming pool. A pool covered just half the time can save up to 50 percent in annual energy costs.

A basic pool cover with enough material for a 30-foot by 15-foot (4.6-by-9.1 m) pool will cost around $80. A storage reel for the cover costs about $160. A high quality insulating pool blanket can cost up to $700 for a 30-foot by 15-foot pool.

Reducing the water temperate just four degrees, from 82 to 78 degrees (27.2 C to 25.6 C) , can cut your pool's natural gas costs by as much as 40 percent. If you live in a sunny region you might consider installing a solar heating system for your pool.

Table 1 shows some savings estimates for pool covers. To use this table to estimate costs for you pool, divide your pool's surface area (sq. ft.) by 1,000 then multiply this number by the heating costs and savings figures for your pool type in the location that most similarly matches your local climate.

For example let’s say you live in Chicago and have an outdoor pool that is 30 x 15 feet. Your pool’s surface area is 450 square feet. Divide 450 by 1000 to get a value of 0.45. From the table you find the annual heating costs for an outdoor pool in Chicago is $1,024. Multiply this by 0.45 to get an estimated annual heating cost of $461.

Table 1: Estimated Swimming Pool Heating Costs and Savings (from the U.S. Department of Energy RSPEC! pool efficiency program)
  Pool Table 
*Fuel cost assumption: Gas, $0.50/therm 


Leak Detection

Even minor swimming pool leak can cause substantial damage and result in huge water bills and it is estimated that one in every 20 swimming pools has a leak.  All pools, hot tubs, fountains and water features are subject to leaks.  Common locations for leaks are where the pool and pipes are joined, at separations along the pool top, in the water supply and return lines to the filtration system, and in the liner, sidewalls and floor of the pool itself.  Leaks are also found around the pump seals and o-rings. Installing a water meter on the pool makeup line is the most effective way of monitoring water use and detecting leaks. The approximately $150 meter installation cost can save you thousands in unecessary water losses.  For commercial and public pools, a meter on the make-up water supply line is vital to efficient pool operation and maintenance.

Just how serious can a leak become? A pinhole-sized leak in a pool plumbing system with 40-pound pressure (psi) will lose approximately 970 gallons (3.67 m3) of water in a 24-hour period. This comes to about 30,000 gallons (113.5 m3) a month or 360,000 gallons per year (1,361 m3). That's enough to drain and refill the average residential swimming pool more than a dozen times.

In addition to an astronomical water bill, there are other warning signs of hidden leaks in pools and spas. Among them are a loss of one-eighth inch or more of water in a 24 hour period, algae formation too soon after chemical treatment, loose or falling tiles, pool deck cracks, gaps and cracks in the pool shell, a settling of the whole pool or spa structure into the ground or constantly damp soil surrounding the pool and/or under the house.

Another leak indicator might be a letter from your neighbor's attorney advising you that your leaking pool is destroying their foundation.  Pool leaks can erode soil under home foundations, causing catastrophic damage to your home, or your neighbor's home.

Many people believe that water loss in a pool or spa is due to evaporation instead of a leak. If you are among these believers, here's a neat trick that will help solve the mystery. Place a bucket on the top step of the pool and fill it with water to the pool's water level.   Also, turn off the water to the automatic water refill system if your pool has such a device.  After a day, if the water level in the pool is lower than the bucket, there probably is a leak in the pool structure or plumbing system.

To further detect whether the cause is the structure or the plumbing system, measure the water loss with the pump running for 24 hours and again with the pump off. If more water is lost when the pump is running, the plumbing is probably the cause.

Thanks to state-of-the-art technology, most pool or spa leaks can be found and repaired without major disruption or the need to take out a second mortgage. Sophisticated detection equipment along with a qualified technician can often find even the smallest leak - even one only the size of a pinhead.  The latest in high-tech leak detection equipment uses a special television camera that is snaked through plumbing pipes to spot leaks. The camera delivers a clear picture on a video screen showing the problem while a transmitter located in the camera head pinpoints its location. Although this system is used primarily for sewer and drain leak detection, it is also used to detect leaks in swimming pool pipes.

Another modern means of detecting leaks below concrete pool decking or in pool walls is a super sensitive microphone. By injecting air or inert gas into a pipe, then listening electronically for sounds of air or gas escaping, the technician can precisely locate the leak. Once the location has been determined, the repair can be made with minimal damage, often in an area as small or smaller than one square foot.

When a television camera or sound won't do the trick, air can save the day. With this method, compressed air is used to pressurize a pipe. The air displaces the water in the pipe until it reaches the leak, at which point bubbles escape from the hole to reveal the problem area. Or, where a pipe fails to maintain a constant air pressure, a leak exists.  Caution: Exposed plastic pipe should never be pressurized with air above 5psi.

A not-so-new method of detecting cracks in a pool structure is the use of dye. The key to this method is to monitor the flow of the dye in the water. Once a leak has been found in a pool wall it can be repaired with an epoxy or high-pressure injection system that will fill even microscopic fissures along the entire length of a crack. Many of these techniques can be performed even while the pool is full of water-another water saver.

You should expect to pay about $175 to $250 for high-tech leak detection, depending upon the location and complexity of the problem. Repairs are extra.


Maddaus, Lisa and Mayer, Peter. (2001). Splash or Sprinkle? Comparing the Water Use of Swimming Pools and Irrigated Landscapes. 

Koeller, J. (2004). Swimming Pool Cover Rebate Follow-up Customer Survey.

[1] Wikipedia contributors, "Swimming pool," Wikipedia, The Free Encyclopedia, http://en.wikipedia.org/w/index.php?title=Swimming_pool&oldid=127665147 (accessed May 2, 2007).

[2] Wikipedia contributors, "Hot tub," Wikipedia, The Free Encyclopedia, http://en.wikipedia.org/w/index.php?title=Hot_tub&oldid=126714125 (accessed May 2, 2007).