Saving Our Industry’s Most Precious Resource: Water
15 Sep Saving Our Industry’s Most Precious Resource: Water
by Scott Webb September 15, 2011 10:45 AM
We tend to think of the pool industry in terms of construction and maintenance or perhaps sanitizing, but it’s the water itself that people like; it’s what they’re truly paying for — the joy of immersion in fresh, clean water.
If that’s the real product, then helping to maintain the supply must be considered a core business interest. And in recent years, the supply of water in some areas of North America has become a cause for concern. Limited water stocks have always been an issue in the American Southwest, but the past decade has seen that traditional zone stretch far to the east.
According to a report on July 12 by the United States Drought Monitor, nearly 30 percent of the land in the contiguous United States is currently affected by drought. About 12 percent of the country is in an “exceptional drought,” the worst category measured. This area of extreme aridity is centered on Texas, and stretches north to Kansas, west to Arizona and east to Georgia.
While drought in America has driven the development of measures to save water in pools, even more acute water supply problems in the last decade have caused the vibrant Australian pool market to develop water-saving products and policies at an accelerated pace.
With severe water shortages pressing Australia in the last decade, “The whole pool industry was caught up in restrictions put on domestic water use. Commercial pools also fell into that area, but as a business they had to develop their own water management plans,” says Julian Gray, CEO of Smart Approved WaterMark, a not-for-profit water conservation organization based in Sydney.
These restrictions were designed to steer consumers toward use of water-saving products or procedures. “In some places, for instance, if somebody wanted to top up their pool with [municipal] water, they could only do it if they had a rain tank or both a rain tank and a pool cover.”
One of the really good ideas being pushed in Australia and in the American Southwest, Gray notes, is the notion of the water neutral pool. “It’s the idea that you conserve as much as you can and if you use any [municipal] water, you replace that use with water savings elsewhere.”
This means, of course, that the home’s overall water usage remains flat, despite the ongoing operation of a pool on the premises.
A water neutral pool, or indeed any comprehensive approach to water savings, focuses on three main modes of water loss: evaporation, backwashing and leaks. Of these by far the most important is evaporation.
The best way to prevent your pool water from simply drying up is to use the No. 1 conservation tool in the industry — the pool cover. By placing a barrier between pool water and ambient air, evaporation is reduced to what vapor can escape around the edges, and this not only prevents the loss of tremendous amounts of water but like amounts of energy.
According to a study released by the NRDC, increasing the temperature of 1 gallon of water in a pool by 1 degree F requires 8.3 BTU of heat input. But when 1 gallon of already heated water evaporates from a pool, it takes approximately 8,700 BTU of heat with it, which needs to be replaced with subsequent pool heating to maintain a constant temperature.
This same study found that more than 50 gallons of water evaporate from an average uncovered pool every day. This suggests that national evaporation loss from inground pools is perhaps 200 million gallons of water per day — enough to meet the daily water use of 5 million homes.
Covers differ in their ease of use (and therefore their likelihood of being used), but they all have a profound effect on water usage. Bubble covers or solar covers are quite inexpensive and good at reducing evaporation. In this sense, dollar spent for dollar saved, they are perhaps the best value in water conservation products.
Vinyl covers are made of heavier material and have a longer life expectancy than bubble covers, and when installed with an automatic retraction system, cost a great deal more but, being automatic, are much easier to use. In addition, these covers provide important safety advantages as, unlike the bubble cover, they can prevent access to the pool. Unpowered retractable covers are also available — these covers roll out over the pool when deployed, and then back into a long rectangular metal box at the end of the pool for neat, tidy storage while the pool is in use.
More recently, the industry has seen the introduction of liquid film covers, which provide a microscopic layer over the top of the water, which reduces evaporation.
Poured onto the surface of the pool, these products contain ingredients which are lighter than water and float to the surface. Attractive forces between the molecules of the liquid cause them to form a very thin barrier to evaporation over the whole pool surface. When bathers are in the pool, the layer breaks apart to allow normal activity, but then reforms whenever the water becomes calm.
A secondary consideration, after the crucial vapor barrier, is the relative speed of the ambient air molecules above the pool — that is, wind.
Wind is a principal driver of evaporation rates, and there are several practical ways of defeating it. Positioning of the pool in the lee of some windbreak is a good start, and solid fencing and thick landscaping can go a long way in cutting down evaporation, as well as other pool nuisances, from chilled bathers emerging from the pool to added sanitizer demand from wind-borne debris.
As conservation advocates have examined the pool, looking for water savings, they’ve identified lesser but still important sources of evaporation — this includes everything from splashing in the pool itself to fountains, waterfalls, negative edges, deck jets and laminars, to water that is splashed out of the pool.
Anytime water is squirted or splashed into the air, whether manually or mechanically, the evaporation rate is raised. Now, no one is arguing that kids should act with mature restraint during chicken fights, but simple awareness of these means of water loss can lead to sensible reductions in evaporation.
For instance, Rodney McCall, National IntelliFlo Field Application Specialist for Pentair, points out that variable-speed pumps allow a homeowner to run water features at lower flow rates, which can reduce evaporation without compromising the visual effect for which the feature was installed.
Also, pumps that are equipped to maintain a flow rate can prevent pressure losses as the filter clogs from reducing a deck jet from an arcing stream to an unproductive and wasteful dribble.
Backwashing is a procedure that is performed tens of thousands of times every day in summer across North America, and each time, anywhere from 50 to several hundred gallons of water are sent down the sewer. Even using the most conservative estimate, that means millions of gallons of water are flushed down the drain every day in backwashing.
For this reason, cartridge filters (which are merely hosed off and not backwashed) are clearly superior to their sand and DE counterparts in terms of water conservation.
But there are other ways to reduce backwashing losses for sand and DE fans. One is to extend the filter cleaning cycle, thereby necessitating fewer backwashes per year. There are several ways of doing this.
One way is to prevent dirt from entering the filter in the first place with a prefilter. Zach Hansen, technical services engineer at Biolab is a fan of this technology. “With a prefilter, you just install it ahead of the filter, and it traps the larger particles so they don’t fill up the main filter and then need to be backwashed. This kind of product helps a lot.”
Another way to lengthen the filtration cycle is by expanding the size of the filter or increasing the dirt-carrying capacity of the media itself. Bigger filters take longer to fill up with crud, and therefore require less-frequent cleanings, while supplements and replacements for sand filter media can have the same effect, manufacturers say, by allowing the media to collect dirt longer.
Besides evaporation and the backwash valve, there’s one more exit from the pool that needs attention from the water conscious professional, and that is through a crack in the pool or plumbing.
Nobody really knows how much water is lost each year through simple leaks, because many people don’t even realize they have them, but the amount is certainly large.
Detection is the real issue here. Once identified as a problem and pinpointed, a leak, while sometimes not easy or cheap to fix, is a straightforward patch or replacement job.
There are high- and low-tech approaches to leak detection, from old-fashioned detective work and deductive reasoning to plumbing pressure tests to air injection and the use of listening devices to pinpoint the hissing sound of escaping air. Sophisticated electrical discharge equipment is available, too, that uses the natural conductivity of water and the insulating properties of an intact pool wall to find the leak. (When a small electrical charge is released in the pool, it cannot penetrate the pool wall but will follow the leaking water in its quest for ground.)
Another tool the pool professional may use to find a leak is the same type of equipment used in the sewer maintenance industry, which uses a lighted scope on the end of a flexible cable to snake through plumbing with a video camera to actually see on-screen what is happening down underground.
In promulgating these ideas, the goal is to keep owners, builders and service techs mindful of the same kind of fundamental notions of water economy as are common in the petroleum world. In the back of most people’s minds is the idea that gas should never be wasted, and most average citizens try to be thrifty in its use. Before too long, water will be thought of in the same way.
With several million pools of various types in operation, small changes can have a large effect. And large changes, like the purchase of a pool cover, could change the trajectory of a major societal challenge.