Evaporative coolers use a substantial amount of water, which could present a problem during times of drought. Depending on the severity of the drought and how much water your cooler uses, you may want to look into the following options:
- Install a thermostat and timer on your cooler so it only operates when necessary.
- Use a two-speed blow motor. Operating at low-speed uses less water and is more energy efficient.
- Inspect your cooler monthly and perform maintenance as necessary to be sure that your cooler is operating efficiently.
- Use alternative methods of cooling, including fans or an air conditioner if you have one. (However, be sure not to precool air using an evaporative cooler before turning on an air conditioner. This causes the air conditioner to use more energy).
- Install a bleed-off clamp on your bleed line to limit the amount of water drained. This could save 4 to 14 gallons per hour depending on your system!
- Re-use bleed water in your yard for irrigation. (But don’t forget to adjust your current sprinkling schedule appropriately!)
Figure 1: El Paso Water is currently promoting water restriction clamps for their customers. Bend the metal and slide plastic tubing into clamp. Tighten screw into desired position.
In addition, below are some “Cool Rules” developed by Water Wise of the University of Arizona Cooperative Extension for saving water during a drought.
- Be brave, delay turning on your cooler until the outside temperature reaches 85 degrees rather than turning it on when it is 79 degrees. You will use 50% less water.
- Turn on the water pump a few minutes before turning on the fan. This saturates the pads first, making your cooler more efficient.
- Open a window a crack in the rooms you are cooling. This will draw the cooled air through these spaces.
- Use ceiling fans to circulate air within your home.
- In the evenings, operate your cooler fan without the water pump. Cool air will be moved through your house without using any water.
Evaporative Cooler Water Use
Evaporative coolers use a substantial amount of water to run. Systems with bleed valves and sump dump systems use the most water. This should be taken into consideration in areas where water is expensive or in short supply.
A study conducted by the University of Arizona’s Office of Arid Lands Studies at the request of the city of Phoenix tried to quantify exactly how much water is used by evaporative coolers. The study found that average daily water use was 66 gallons per day, or 14,000 gallons per year (212 days of cooling).
Coolers without a bleed valve used an average of 3.5 gallons per hour, while the coolers with a bleed valve used 10.5 gallons per hour. The percentage of household water used by the coolers was 25.8% for households without air conditioning, and 15.8% for all houses. On average, coolers ran 2,100 hours during the summer. Similar results were found in a study conducted in El Paso, Texas.
| Average water use (gal/hr) | Average run time (hr/yr) | Yearly water use (gal/yr)* | |
| Without bleed | 3.5 | 2,100 | 7,350 |
| With bleed | 10.5 | 2,100 | 22,050 |
In general, the amount of water used by your evaporative cooler will depend upon its size, air movement, and the relative humidity of the air. All things being equal, a 4500 CFM cooler uses less water than a 6000 CFM cooler. However, the most important difference is water usage rates for evaporative coolers is the use of bleed water.
Thermostats and timers can be utilized to decrease the amount of water (and energy) used by evaporative coolers. A thermostat can be set to a certain temperature so that the evaporative cooler is only used when necessary. In addition, timers can be used so that the evaporative cooler can turn on just before residents get home.
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Gino
Saturday 22nd of June 2019
Turning the Swamp off and running AC made no sense to me either. I had a house in Phoenix with central swamp cooling (which worked well into July-ish) and 1 large AC window unit in the living room which sort of kept the house cool if we shut down the Swamp and exterior windows, kept all of the interior doors open, ran fans, etc. It was always TWICE the cost of running swamp. Needless to say, we avoided AC until we just couldn't stand it anymore. Also, I understand that Swamps "use" water to run, (as in they add to our utility bill costs), but the water isn't wasted or "gone" from an ecological standpoint- that's like saying waterfalls or waves crashing on the shore use water. I'm thinking one could use an aquarium air-valve (they're continuously adjustable) on the Bleed-Off Line to regulate just how much water gets bled off, and adjust it according to how nasty the pads get over time....?
Debbie
Friday 7th of July 2017
Window swamp coolers - 5500-5900 cfm - bleed off 1.5 to 3 gallons per hour. If you restrict the bleed off, mineral deposits will build up and the cooler will not work efficiently and will need to be replaced more often. It is very easy to use the bleed off water for other things, water for pets, plants, washing patios, whatever. To suggest to use an air conditioner over a swamp cooler to save water is ridiculous. Energy is at a premium also. We live in Vegas, and to even think of turning on the cooler before it's over 87 in the house is unheard of, I don't know anyone that would turn on the water, and not fan only, if it's below 85 outside. By the time it's 88 in the house, it's generally 115 outside - and that's when we turn ours on.