Watering a Lawn vs. Putting in a Pool: Essential Answer

May/June 2010

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Q: Now that we are facing drought and climate change, I am wondering about the sustainability of our green lawns we love so much in Sacramento Valley. Which is more efficient, keeping your lawn green or replacing it with a swimming pool? I seem to remember reading once that a swimming pool actually wastes less water per square foot than a lawn. Is that true?

Asked by Bill Tournay, ’65, Sacramento, Calif.

Astute observer, your question is not new to me, but you put an unorthodox spin on it. Lawns versus swimming pools? I have often heard about sustainable alternatives to lawns, but never have I heard mention of pools!

If you're interested in which uses less water, the answer is quite simple: a pool. According to Stu Campbell's The Home Water Supply: How to Find, Filter, Store, and Conserve It, a lawn requires 0.6 gallons of water per square foot each day, compared to 0.3 gallons for a pool. However, as you've pointed out, sustainability is a complex issue that involves more than just water usage.

Drought. Climate change. Efficiency. Waste. You've touched on a lot of issues that need to be considered in sustainability. All of these issues come into play when considering the sustainability of lawns and swimming pools.

Drought has an obvious connection to pools and lawns, as they both use a lot of water. According to the California State Department of Water Resources, the state has experienced below average precipitation and runoff for three years in a row. The drought is so bad that for the first time in 18 years there are mandatory restrictions on water usage.

California's water problems aren't likely to be solved any time soon, according to the California Climate Change Portal, a state government information site. The Portal reports that climate change is shrinking the glaciers in the Sierras that the Sacramento Valley relies on for summer water flows. This will lead to more severe droughts in the summer and more severe floods in the winter.

If we were only concerned with saving California's remaining water, we'd give up lawns and pools altogether, but you bring up an important point: Californians love green lawns. We are unlikely to give up lawns, pools or other water-intensive luxuries to be more sustainable. That's why sustainability is so difficult to achieve—while we want what's best for the environment, we also want what's best for ourselves, and these things often conflict.

One easy way to reconcile some of the differences between what we desire and what's best for the environment is to simply be more efficient and waste less. That way we can still have our pools and lawns, but use less water and be more sustainable. For lawns, this could be as simple as watering in the morning instead of during hot parts of the day when more water is wasted due to evaporation. You can cover pools when no one is swimming, to help stop water loss to the atmosphere.

Lawns and pools aside, the greenest solution is to put native plants in your yard—they only need what nature provides, no artificial irrigation required. You might not have the green lawn that everybody loves, but mother earth will love you all the more and you can set a great example for the rest of your neighborhood!

Nick Jachowski plans to receive his master's in earth systems in 2010.

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