State likely underestimates volume of water used to fill swimming pools

Tue, 05/20/2008 - 4:02pm
By: Letters to the ...

This is a rebuttal to Ms. Pitts’ response (“In defense of filling swimming pools during drought”) in the May 7 edition of The Citizen. She presented a response to my letter concerning water restrictions that was in the previous week’s edition.

I commend her efforts to defend her privilege to use the county’s water to fill her swimming pool by listing items that I had not considered relevant. She could have merely cited the law and that would have been that.

Be that as it may, it is unfortunate that our highest elected state official has signed into law an unbridled exemption on using our water resources to fill swimming pools. Such unconditional usage was not voted on by the voters.

What initially prompted me to write my letter was that, in my opinion, the water restrictions that allowed the filling of swimming pools without restrictions while not allowing one to wash a vehicle at one’s own residence, as well as the stringent limitations on watering of lawns, were unreasonable.

According to an announcement titled, “Governor Perdue Signs Water Plan into Law,” dated Feb. 6, 2008, on the website, Gov. Perdue modified restrictions on the filling of swimming pools. In doing so, he stated, “We believe the swimming pool exemption will have only a modest impact on water supply, provided citizens can still meet the required water conservation goals.”

The same announcement also states, “It’s estimated there are approximately 6,500 public pools and 92,000 private residential pools in the Level Four area (which then consisted of 61 counties, now 55, which computes to over 100 public pools on average per county). According to EPD, those pools will require 7 million gallons of water per day from April through September.”

The announcement does not provide details as to how EPD determined the per-day volume. Based on the state’s estimates, there are 98,500 pools that use 7 million gallons of water per day. That computes to approximately 71.066 gallons of water per day per pool. This per-day volume is a very nominal amount, assuming the state’s estimates are reasonable.

However, the numbers relating to water needed for filling swimming pools as well as the mere use of water for such purpose can be questionable, I think, especially when it is proclaimed that we remain in a drought period, and even more so when the pencil is applied to provide other perspectives.

So, let’s look at the state’s estimates from another perspective. If my math is correct, the total amount of water to be used during the entire six-month period is computed as follows: 7 million gallons per day x 180 days = 1.26 billion gallons for the 180-day period.

The total equates to 9.538 billion bottles of drinking water containing 16.9 fluid ounces, which is enough to serve 6,623,750 people with eight bottles of water each day during the 180-day period.

Although I have never measured how much water I have used in the past for washing a vehicle, I think a reasonable estimate would be not more than 50 gallons of water on average. But let’s assume 100 gallons for conservative computational purposes and further assume the vehicle is washed once a week for six months or 26 weeks.

So, during the same six-month period how many vehicles could be washed once a week? Again, if my math is correct, that computes to 484,615 vehicles that could be washed once a week during the six-month comparison period.

By the way, I have not washed a vehicle at home since the restrictions have been in effect. Neither do I visit a car wash. Instead, my wife and I now leave our vehicles outside and let the rain wash them, especially to remove the pine pollen.

Instead of washing my car at home, which is prohibited, Ms. Pitts suggests that I use a commercial car wash. I seriously doubt there would be any significant water savings using a commercial car wash rather than washing a vehicle at home.

Moreover, I have never found the use of a commercial car wash to be very appealing, probably for reasons akin to why some people would not visit a public swimming pool, preferring to use their own private residential pool.

I have no problem with anyone choosing to use a commercial car wash, but please do not impose that upon me when I have access to water at my residence and the equipment necessary to adequately wash my vehicle without the hassles of a commercial car wash.

It is understandable that in order to benefit from owning a private residential pool one would need to refill it after replacing a liner. Then, for convenience one would probably choose to use the county’s water supply to fill the pool, and of course one would be totally in compliance with the law in doing so.

But one does have the choice of filling or not filling a pool. That fact remains, notwithstanding the blessings of exemption.

Not owning a swimming pool, I certainly was not aware of all the requirements for pool maintenance and in retrospect do not find it relevant based on the language used within the restrictions. In preparing a rebuttal I have, however, performed some research of swimming pool maintenance using the Internet, and found information provided on the website for the Association of Pool and Spa Professionals (

On the APSP website, there is link to a document titled, “Swimming Pools and Water: Myths and Facts,” which supports Ms. Pitts’ argument for water remaining in the pool year after year. But that is not the full story, and I might add that water not only is splashed out, but also evaporates, which Ms. Pitts briefly mentions, but seems to infer that this is insignificant.

The APSP document discusses winterization of pools, both in-ground and above-ground, with in-ground pools being drained on average six inches for the winter. It also discusses using other sources of water, other than municipal water supply, for top-off, a term not used in the defense letter or by the state. Among the other sources that could be used for top-off is having water trucked in from other areas.

I found this somewhat ironical since Ms. Pitts suggested that I use a commercial source for washing of my vehicle. The APSP document also describes three conservation ways for topping off pools, two of which seem practical for our region (use of solid covers to collect water which then could be filtered and extensions from a home’s downspouts).

What intrigued me was a discussion of evaporation relating to the Northeast Region where industry experts had determined there was an average of one-eighth-inch loss of water per day during a 15-week swimming season, a period that is 11 weeks shorter than the presumed 26-week period noted in the estimates by our state.

The document also discusses backwashing and rinsing of the filtration system, which was said to cause water loss ranging from 50 to 300 gallons every two weeks or 375 to 2,250 gallons for the swimming season (Northeast). That’s per pool water loss. So, one can easily compute estimates of water loss for 98,500 pools.

I might note that the water restrictions exempt the filling of swimming pools, but one might question whether backwashing and rinsing was considered to fall within the exemption of “filling swimming pools.”

Of course, once the skids are adequately greased in support of filling swimming pools by citing risks to public health and safety, I presume the same argument could be made in support of backwashing and rinsing.

Of course, loss of water due to evaporation in a swimming pool depends on a number of factors, such as temperature, humidity and wind. The map and APSP information suggest that the water loss for our area would be twice that of the Northeast.

Based on this information, it seems that the amount of water needed just to top off a pool to replace evaporation losses is on average higher by almost 30 gallons per day, or 5,400 gallons for 180 days for one pool. Hence, the state’s estimates might be understated.

Of course, it is not known what the state considered in determining the per-day volume for filling the public and private swimming pools since details of its method were not disclosed in the announcement.

Owning a residential swimming pool is luxury, not a necessity, unlike owning a vehicle that is used for conveyance. Maintaining a vehicle, including regularly washing of one, is part of the owner’s responsibility to protect an expensive asset. Regular washing and occasional polishing is necessary to protect the paint.

Hence, it seems reasonable to conclude that the best place to wash a vehicle, especially before waxing, is at home, rather than to make a trip to a commercial car wash and to use a costly crude oil derivative (fuel) of another precious, but dwindling, resource.

I’d like to say that I would have no qualms about using water for a swimming pool (e.g., public, YMCA or hospital pool) that is used to provide swimming lessons, life-saving courses, therapy and similar functions, provided there is not a more pressing need for water usage.

A. Russell

Fayetteville, Ga.

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