EPA

4

WaterSense

JUMP Into

Pool Water Efficiency


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EPA

WaterSense

Thoughtful residential swimming pool design and ongoing maintenance can
help save pool owners water, energy, and money. Addressing issues related
to evaporation, water quality, leaks, or pool usage can all save water. The U.S.
Environmental Protection Agency's (EPA's) WaterSense® program developed
this guide to help residential pool owners and maintenance professionals
understand and minimize pool water use. Commercial pool owners can find
additional information in WaterSense at Work: Best Management Practices for
Commercial and Institutional Facilities at www.epa.gov/watersense.

Introduction

Pools provide a fun and relaxing way to keep
cool during warmer months. However, if not
adequately maintained, your pool could be
sending water and money down the drain.
Pools can consume water through evaporation,
pool cleaning, leaks, and splashing. Investing
in new equipment or employing targeted
maintenance techniques can save water,
energy (for heated pools), and money.

This guide provides an overview of design
considerations, retrofits, and maintenance
practices that are aimed to improve the water
efficiency of residential pools. WaterSense
developed this guide with a focus on in-
ground and above-ground residential
pools, but many of the practices also apply
to commercial pools or spas. For more
information, consult the additional resources
listed at the end of this document.

Evaporation

Evaporation is one of the leading causes of
water loss in residential pools, especially in hot,
drier climates where pools are most prevalent.
The rate of evaporation from a pool is
dependent on a number of variables, including
temperature, humidity, and wind speed. EPA
estimates that, depending on climate, an
uncovered 500-square-foot swimming pool
could lose between 12,000 and 31,000 gallons
of water per year due to evaporation, with this
number being even higher for heated pools.
Not only does this contribute to water waste,

but it can also cost homeowners money!
Reducing water loss from evaporation is the
best way to reduce overall water usage in your
pool.

Size Pools for Use

A pool's surface area directly impacts the
volume of evaporation that may occur. In
effect, the larger a pool, the more water that
is likely to be lost due to evaporation. Further,
a deeper pool requires more water to fill and
more resources to maintain (e.g., filtration,
chemicals, heating).

Therefore, when planning a new pool
installation, consider how you want to use the
pool and select a size and design that will meet
your needs while minimizing potential water
usage. A smaller pool design can result in lower
maintenance costs and helps reduce water
consumption.

Cover Up

Pool covers are the most effective method
of reducing water losses from evaporation.
When in use, solid pool covers can reduce
evaporation by more than 90 percent and, in
the case of heated pools, save between 50 and
70 percent of pool heating costs.1 Any pool can

Cover Your Bases

According to data collected as part of
the 2016 Residential End Uses of Water
study, only 15 percent of pool owners
have and regularly use a pool cover.2

'Minos, 2021
2DeOreo et. al., 2016


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Table 1: Types of Pool Covers and Their Attributes

Type

Effectiveness
at Reducing
Evaporation
When in Use3

Can It Serve
as a Safety
Cover?

Additional Information and
Considerations

Solid/mesh/hybrid

Up to 95 percent

Yes

Mesh covers are lighter weight
than solid covers but allow more
evaporation to occur.

Solar (bubble cover,
solar rings, thermal)

50 to 95 percent
(varies based
on shape and
coverage)

No

Solar covers are designed to use
the sun's energy to heat the pool.

Liquid evaporation
suppressant

15 percent

No

Non-toxic, chemical evaporation
suppressant is applied to pool
surface on a regular basis.

Figure 1: Solid Pool Cover

Figure 3: Reel Used For Applying Bubble
Pool Cover

3 Mul eta, 2016

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Safety First

When purchasing a cover for your
pool, prioritize safety, in addition
to potential water and energy
savings. Safety covers help inhibit
pool access by children, animals, or
other unwanted swimmers during
unsupervised periods.

Pool covers can be certified as
safety covers under ASTM F1346-
91. the Standard Performance
Specification for Safety Covers and
Labeling Requirements for All Covers
for Swimming Pools, Spas and Hot
Tubs. The standard test methodology
includes tests for load bearing and
surface water drainage, and also
ensures no openings are present
between the cover and pool. Many
states and local jurisdictions have
established safety requirements for
residential pools, and in some cases
require a safety cover if fencing and
locked gates are not installed.

be retrofitted with a cover, so if your pool
doesn't have one, this is the most effective first
step you can take to reduce evaporation. If you
already own a cover, use it as often as possible,
as covers are only effective at reducing
evaporation when they are applied.

Pool covers can be made from a variety of
materials and can significantly vary in terms
of cost, usability, safety, and efficiency. Solid
covers prevent debris and precipitation from
entering the pool, but water can collect on top,
which may require a pump to remove. Mesh
covers allow some debris and precipitation to
pass through, so no water will collect on top.
Table 1 on page 3 displays the most common
types of pool covers on the market and their
associated attributes.

Pool covers are only effective when applied to
the surface of the pool; therefore, pool owners
should consider ease of use when making a
purchase so that any time the pool is not in
use, the pool cover is. Automatic covers, which
are installed on a track at the edge of your pool,
can be deployed at the press of a button and
can take the heavy lifting out of pool cover
use. If an automatic pool cover is not practical,
a motor-driven reel or hand crank can be used
with some types of covers to help guide the
cover over the pool surface.

Winter covers are a subset of pool covers. A
winter cover is used over an extended period
during the pool offseason to protect it from
damage and debris. Winter covers can be more
secure and typically double as safety covers,
but often are not practical to be used on a daily
basis for evaporation reduction.

Some utilities offer rebates of up to $200 for
qualified covers. Check with your local water
utility to see if they offer a rebate to purchase
and install a pool cover.

Cool Off

Water temperature affects the evaporation
rate of a pool, since higher temperature water
evaporates more quickly. In a heated pool,

evaporation reduces the water temperature,
which means additional energy is needed to
keep the pool at the desired temperature. Most
heated pools are kept between 78°F and 82°F,
and depending on your location, each degree
increase could increase energy costs by 10
to 30 percent.4 For an outdoor pool, keeping
the pool temperature lower can reduce
evaporation and heating costs. For an indoor
pool, keeping the ambient air temperature
higher than the water temperature can reduce
evaporation. If you are planning to be away for
several days, be sure to turn the pool heater off
or turn the temperature down. Don't forget to
throw on a pool cover, too!

Other Ways to Reduce Evaporation

Many pools have water features such as
fountains or waterfalls. While these features can

4

4Minos, 2021


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Pump It Up

Pool pump upgrades can make your
circulation system energy-efficient
and extend the life of your pool filter.
Beginning in 2021, pool pumps sold
in the United States are required to
be variable-speed pumps. A variable-
speed pump offers substantial energy
savings compared to older models.
ENERGY STAR® certified pool pumps
take energy efficiency even further,
reducing energy use by 11 to 18
percent.6

be aesthetically pleasing when the pool is in
use, the turbulence added to the pooi surface
increases evaporation and can also result in
water lost to wind or splashing. To reduce
water loss, only turn on these features when
the pool is in use. Alternatively, put water
features on a timer to make sure they turn off
after a set amount of time or at night.

Installing a windbreak to reduce wind speed
around the pool can also help to reduce
evaporation. Landscaping or other physical
barriers, such as stone walls or fencing, can
increase wind protection. Increasing shade
through landscaping can also keep the pooi
cooler and reduce the effects of evaporation.
Be sure to carefully select landscape plants so
they don't contribute more debris to the pool.

Water Quality

Maintaining a pool's water quality keeps water
safe and looking clean for swimmers, but it
can also reduce water loss! The California
Urban Water Conservation Council (CUWCC)
estimated that 23 percent of quantifiable pooi
water use is attributed to filter backwashes,
the process of sending water backwards
through a filter to remove debris build-up,
and 21 percent is attributed to control of

total dissolved solids (TDS), which can only
be maintained by dumping portions of
contaminated water and replacing it with
fresh water.5 Keeping a pool free of debris
and microbes can reduce corrosion, decrease
the risk of developing leaks, and increase the
longevity of your pool water.

Filtration

Deploying a high-performance filter can
keep debris out of a pool and reduce the risk
of leaks. Filters range in their filtration ability

5Koellerand Hoffman & Associates, 2010
SENERGTSTAR, n d.

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Table 2: Types of Filters and Their Attributes

_.1JL _ _.1JL J_. ..	Water Filter Media Maintenance Practices

Filter Type Filtration Ability Usage Lifetjme and other Notes

Sand

20 - 40 microns7

6666

3 - 6 years7

• Backwash once per week

Glass

5 microns8

666

7 -15 years9

•	Backwash once per week

•	Alternative to sand with
shorter backwash cycles

•	Requires less frequent
replacement of media
than sand filters

Diatomaceous
Earth (DE)

5 microns7

66

2 to 3 years
(grid lifetime)8

•	Backwash every 4 to 8
weeks

•	DE media must be
added after every
backwash

•	DE can be harmful if
inhaled

Cartridge

10 microns
(can vary)7

6

2 to 4 years7

•	Frequency of cleaning
depends on cartridge

•	Clean by spraying with
hose, no backwash
required

(measured in terms of the smallest particle they
can filter out); cost; maintenance practices; and
water efficiency. Filtration ability is discussed in
terms of microns (one micron is one millionth
of a meter). The smaller the micron that can be
removed, the better the filtration ability.Table
2 displays the main types of pool filters on the
market and their associated characteristics.

Each filter type has its advantages and
disadvantages. Sand filters are the most
commonly used filter type for residential
pools due to lower initial cost and ease of
maintenance. A comparable, but more water-
efficient, alternative to sand filters is a filter
with glass media, which allows a shorter
backwash cycle. Glass media can often be
used as replacement media within an existing
sand filter. Cartridge filters are the most
water-efficient because they do not require
backwashing. Using oversized cartridge filters
can also cut down on water use because
cleaning frequency is reduced. Diatomaceous

Earth (DE) filters offer the highest performance
but are also the most costly and require
additional DE after each backwash.

Heat Up Energy Savings

Take energy efficiency into
consideration when purchasing a new
pool heater. Consider replacing your
gas heater with a solar heater or heat
pump to reduce long-term energy
costs.

If purchasing a heat pump pool
heater, check its coefficient of
performance (COP) to determine the
energy efficiency. COPs typically range
from 3 to 7; the higher the COP, the
more efficient the heater.10

Check the DOE's Energy Saver pages
on efficient pool heaters for more
information.

6

7Koellerand Hoffman & Associates, 2010 91st Direct Pools, 2021
sGiovanisci, 2021	l0DOE, n.d.


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If you are constructing a new pool, consider
using a cartridge filter to jumpstart your pool's
water efficiency. If you are looking to upgrade
to a different filter type, it is important to know
whether changing filter systems would require
extensive plumbing alterations to operate
efficiently.

The best way to reduce water use is to
minimize the frequency and length of
backwashes or cleanings. Using skimmers and
vacuums to manually remove leaves and debris
can reduce the load on filters and increase
the time before a backwash is necessary,
installing a pressure gauge on the filter can
help determine when it is time to backwash.
When the water pressure increases by 10
pounds per square inch (psi), a backwash is
usually necessary. You can also consider using
backwash water on your lawn or garden. Just
be sure the backwash water is not freshly
chlorinated, so it is safe for your plants.

Other Ways to Maintain Water Quality

Other ways to maintain pool water quality
include use of ozone, ultraviolet light,
copper-silver ionizers, reverse osmosis, and
nanofiltration. Ozone is a disinfectant that can
be used in place of chlorine, and ultraviolet
light is a system that sanitizes pool water.
Copper-silver ionizers are used in conjunction
with low levels of sanitizers (e.g. chlorine,
bromine) and release small amounts of copper
and silver ions into a pool, which kills bacteria
and prevents algae growth. All three methods
can be used to reduce the need for chlorine,
which in turn reducesTDS.

Periodic reverse osmosis (RO) treatment or
nanofiltration are alternative methods to
maintain water quality.These processes send
contaminated water through a membrane to
remove particles and generate a wastewater
stream of concentrated contaminants. RO and
nanofiltration can be used to reduce TDS levels
in a pool, reduce the use of chemicals such as
chlorine, and can increase the time before any
pool water needs to be dumped. However, RO
treatment systems can be costly and waste a
lot of water depending on their efficiency so
carefully compare water consumption from
a RO system to other methods of treatment.
While permanent RO systems are generally
impractical to use for regular pool water
treatment, some companies offer mobile RO
treatment, where an industrial-sized RO system
can be brought to a property to clean pool
water. Some of these iarger RO systems can
recover up to 85 percent of the pool water.

This process is an alternative to dumping and
refilling pools.

When working with professionals in design
or pool maintenance, look for companies
with professional certifications, like those
certifications offered by the Pool & Hot Tub
Alliance.

Leaks

One important way to reduce water loss is
to learn to recognize potential leaks. Annual
water loss from poo! leaks is difficult to
quantify, as leaks can often go unnoticed for
extended periods of time. However, small
leaks can quickly turn into big leaks if they go
unattended.


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Do-lt-Yourself Leak Test

It's important to periodically test for
leaks in the pool by performing an
evaporation bucket test.

1.	On a day without rain or heavy
winds, shut down all pool systems
(filtration systems, pool cleaners,
automatic fills, etc.), and close the
pool for 24 hours.

2.	Fill a 2.5- to 5-gallon bucket to
about 1 inch from the top and set
the bucket in the pool (on a bench or
step) such that at least two-thirds of
the bucket is submerged in the pool,
and the bucket water level is a little
higher than the pool level.

3.	Mark the initial water level within
the bucket with a marker, piece of
tape, or by using a ruler to record the
distance from the top of the bucket.
Mark/measure the initial height of the
still pool water the same way.

4.	Leave the bucket for 24 hours, then
re-record the pool and bucket water
levels. If pool water loss is greater than
bucket water loss, the pool may have
a leak.

For more details, refer to the ANSI/
APSP/ICC-13 Standard for Water
Conservation Efficiency in Residential
and Public Pools. Spas. Portable Spas,
and Swim Soas.

Leaks can be found in the pool liner, the pump
seal, pool piping, the pool-to-pipe connection,
pool edges, and in pipe joints. If your pool is
losing more than 2 inches of water per week, or
3 inches in hot, dry areas with high evaporation
rates, then it is likely you have a leak. Wet spots
around the pool, or air bubbles in the water
return pipeline or in the pump strainer can also
be signs of leakage. Installing a water meter can

help you actively monitor water consumption
and identify potential leaks.

You can also add water manually, rather than
automatically, to be aware of your pool's weekly
water loss. If you have an automatic refill for
your pool, then once every three months, the
automatic fill should be shut off for 24 hours to
test for leaks.

Automatic fill valves can sometimes
malfunction and send water to a pool's
overflow drain. Periodically confirm your fill
valve is shutting off properly by plugging the
overflow drain and monitoring if the pool level
is rising. If it is, your fill valve may be stuck in
the open position and should be repaired or
replaced.

In cooler climates, another step to prevent
leaks from forming is to make sure your pool is
properly prepared for the winter. Winterize your
pool by cleaning the pool water and all parts
of the pool, balancing out pool chemicals, and
adding winterization chemicals such as shock
and algaecide, which kills bacteria and algae.
Balancing chemicals is important, as a chemical
imbalance could corrode the pool and lead to
structural damage. It is also important to drain
water from equipment such as filters, pumps,
heaters, and piping, as freezing water can cause
cracks, which can later cause leaks.

Pool Usage

Water can also be lost to splashing and "drag
out," which is the water that is removed as
a person exits a pool. Like leaks, the total
water loss from splashing and drag out is
hard to quantify, but mitigation techniques
can be implemented during pool design and
construction. Many pools are built such that
the pool edges are cantilevered and divert
water back into the pool. An example of a
cantilevered edge is shown in Figure 5 on
page 9.

Some pools also have a gutter or grate system
around the pool edges to drain water back

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Figure 5: Cantilevered Pool Edge

into the pool. Implementing these common
features during the design of your pool will
work to reduce water loss.

You can also reduce water loss from human
activity by preventing overfilling and
maintaining water levels at an appropriate
height. Maintain 4 inches of freeboard, or the
distance from the level of the pool water to the
top of the overflow or pool deck, to prevent
water overflowing when there is activity in

the pool. Also consider plugging the overflow
drain(s) when the pool is being used.

More Ways to Improve Water
Efficiency

While draining your pool should be relatively
infrequent, it is sometimes unavoidable to
make repairs or improve overall water quality.
The frequency at which water needs to be
removed can vary depending on local water
quality and conditions, but a well-maintained
poo! should only need to be drained every
3 to 7 years to keep TDS levels down. If this
becomes necessary, consider opportunities
for water reuse. Before draining, let the water
sit in your poo! for 48 to 72 hours without
adding chemicals; at that point, pool water is
often safe enough for garden or landscape use.
However, be sure to check for local regulations
on poo! water discharge before draining your
pool water into sanitary or storm sewers or
onto your property.

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References and Additional Resources

The following are resources that were used in the development of this guide:

1st Direct Pool. 11 January 2021 ."How Often Should You Replace Your Swimming Pool Filter?"
www.1stdirectpools.com/blog/post/how-often-should-you-replace-swimming-pool-filter.

Association of Pool & Spa Professionals (APSP). 6 January 2017. ANSI/APSP/ICC-13 2017 American
National Standard for Water Conservation Efficiency in Residential and Public Pools, Spas, Portable
Spas, and Swim Spas. American National Standards Institute. https://webstore.ansi.org/Standards/
APSP/ANSIAPSPICC13701 7.

APSP. 2014."Copper-Silver Ionizers."www.phta.org/pub/?id=082CD55C-1866-DAAC-99FB-
D9CCF4076797.

Aguanomics Pools. 23 August 2017."Pros and Cons of Different Pool Filters."
www.aguanomicspools.com/pros-and-cons-of-different-pool-filters/.

ASTM International (ASTM). February 2018. ASTM F1346 - 91 (2018), Standard Performance
Specification for Safety Covers and Labeling Requirements for All Covers for Swimming Pools, Spas and
Hot Tubs, www.astm.org/f1346-91 r18.html.

DeOreo W„ Mayer P., Kiefer J„ Dziegielewski B. 2016. Residential End Uses of Water (REUWS) Study
Update. Water Research Foundation (WRF).

DOE Energy Saver."Swimming Pool Heating." www.energy.gov/energysaver/swimming-pool-
heating.

ENERGY STAR."Pool Pumps." www.eneravstar.aov/products/pool pumps.

Giovanisci, Matt. 4 May 2021 ."How to Select the Best Pool Filter."Swim University,®
www.swimuniversitv.com/pool-filter/.

Koeller, John, and H.W. (Bill) Hoffman & Associates LLC. September 2010. "Evaluation of Potential
Best Management Practices—Pools, Spas, and Fountains."CalWEP,The California Urban Water
Conservation Council, calwep.org/wp-content/uploads/2021/03/Pools-Spas-and-Fountains-
PBMP-2010.pdf.

Let's Pool Together. "Pool, HotTub & Spa Water Conservation Tips." Accessed 1 March 2022.
www.letspooltoaether.com/pool-spa-tips/.

Minos, Scott. 5 July 2021."Stay above Water with an Efficient Swimming Pool." U.S. Department of
Energy (DOE), www.enerav.aov/eneravsaver/articles/stav-above-water-efficient-swimmina-pool.

Muleta, Misgana. January 2016. "Cal Poly Study: Effectiveness of Pool Covers to Reduce
Evaporation from Swimming Pools." National Plasterers Council (NPC), www.npconline.ora/paae/
cal-polv-studv.

Pool & HotTub Alliance. Certification, www.phta.ora/certification/.

Water - Use It Wisely. "Saving Water Outdoors." https://wateruseitwiselv.com/savina-water-
outdoors/swimmina-pools/.

WaterSense. WaterSense at Work: Best Management Practices for Commercial and Institutional
Facilities, www.epa.aov/watersense/best-manaaement-practices.

SEPA

10	PHONE (866) WTR-SENS (987-7367) WEBSITEwww.epa.gov/watersense EMAILwatersense@epa.gov	EPA-832-F-22-015

SEPTEMBER 2022


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