Putting Sustainable Water on Tap
by Fred Horch, Principal Advisor at Sustainable Practice.
The year we’ve had in Maine brings to mind The Simpsons’ version of The Rime of the Ancient Mariner. We’ve gone from drought to saturated soil: moisture content is in the top 95 to 98% of measurements for this time of year. On my bike ride up to the Common Ground Fair, it looked more like spring than fall, judging from the vernal pools with water still in them.
Other parts of the country aren’t so fortunate. According to the U.S. Drought Monitor, 37.78% of the lower 48 states are in drought. We’ll never truly run out of water, though. As a last resort we can use solar power to desalinate brackish water (between 0.5 and 30 grams of salt per liter) or seawater (about 35 grams per liter). As long as our sun shines, our ingenuity abides, and our oceans are full, water will always be a renewable resource. The big question is whether building huge desalination plants and aqueducts is our best idea.
A smarter strategy–one that we can practice in our own homes and organizations–is to use less water. Each of us has our own theory about the most efficient way to wash dishes (to fill the sink or not to fill the sink, that is a question). But did you know that we can save way more water by changing the way we get our electricity than the way we do our dishes?
According to a 2010 study, thermal power plants use 45% of freshwater withdrawals. That’s more than agriculture: irrigation uses only 32% of our total fresh water. Switching to solar power is actually our best opportunity to save the most water, because solar arrays use no water. Some farms are even growing grass and grazing sheep below solar modules, using less water than conventional agriculture because the solar arrays provide shade and reduce evaporation.
While we’re saving water by going solar at home, work, and school, we can also be taking other steps to improve our water efficiency. Our water utilities collect, purify, disinfect, and distribute water that is safe to drink. Can you guess how we use most of it?
The EPA estimates that we use 30% of domestic water supply outdoors, watering our lawns or filling pools. Of the water we use indoors, 24% flushes our toilets and about 12% is lost to leaks. Of all the water we purify to be safe enough to drink, less than 8% we actually drink. A few common sense steps can ensure that we use our drinking water supply wisely.
To reduce or eliminate the need to irrigate our lawns, we can add compost to our soil so it can retain more natural moisture, choose a mix of native plants that do not need irrigation, and use stone and other hardscape in areas that won’t grow plants without watering. If we have an outdoor pool, covering it when not in use prevents evaporation. Rain barrels are an alternative to turning on the tap to water a garden.
The EPA’s voluntary WaterSense label helps us find toilets, showerheads, faucets, and other products that use much less water than standard fixtures. A low-flow toilet uses just 1.28 gallons per flush compared to 6 gallons per flush for older toilets. Low-flow showerheads use less than 2 gallons per minute, while standard shower heads use 2.5 gallons per minute.
For appliances like dishwashers and clothes washers that use hot water, the EnergyStar rating helps us find models that use much less water and energy. Compared to hand washing, the government estimates that an efficient dishwasher saves you about $210 per year–and thousands of gallons of water over its lifetime.
For anyone committed to putting sustainable water on tap, the good news is that we are constantly inventing clever ways to procure, purify, and prudently use clean, fresh water over and over again.
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