3 Water-saving Homes

June 2, 2010

When we think of green and electronics, we usually think of energy efficiency. But conserving water is a fundamental way to be green and more sustainable. Water conservation is a huge concern in California and the southwest—and could be practiced even in areas that get plenty of rainfall.

You can save thousands of gallons of water—and lots of money on your water bills—by installing a rainwater harvesting and irrigation system. The rainwater from your home’s gutters is routed directly to a tank or a series of tanks—then used to water your plantings and lawn.

There are other high-tech ways to save water as well, such as installing a water recirculation pump to get warm water at the tap without wasting cold water—as well as gray water recycling systems that use the water from washing machines and showers.

Water savings measures can add up with systems like these, saving you money and conserving our most precious and life-sustaining resource. Here are three quick case studies in green tech water conservation, along with some helpful advice on systems and costs.

Rainwater Harvesting

“Our water bill to date has been the lowest we’ve had in years, with no excess usage charges,” says Kimberly Lancaster, owner of the Green Life Smart Life green home project in Rhode Island, which uses a 5,000-gallon rainwater harvesting system.

“Our irrigation system, even in how it uses water, is incredibly efficient,” says Lancaster. “It gauges evapotranspiration [how much water is evaporated into the atmosphere] to determine how much water the landscaping needs. We installed native drought tolerant landscaping and in total reduced our lawn’s watering needs by 59 percent.”

Lancaster’s rainwater harvesting system can collect 2,319 gallons from a 1-inch rainfall. And if there’s no rainwater to feed Lancaster’s landscape? In that event, a sensor alerts Lancaster’s geothermal well pump to use that water to fill the cistern.

“It features a float sensor that communicates back to the Hunter irrigation control system,” explains Lancaster. “When it rains the water is diverted to the cistern, whether it needs it or not. If the cistern is full it overflows to four additional galleys [large cement tanks with holes and crushed stone]. If we deplete our supply, the sensor in the tank sends a message to our well supply to call water from our geothermal well, which will fill the tank until the float sensor reaches its optimum level or we have finished watering, whichever comes first.”

Other water conservation features in the home include all Kohler water savings fixtures and fittings. “Our toilets are all 1.0 gpm, our shower heads are all 1.75 gpm and our faucets are all 1.5 gpm. We have ultra-high efficiency water tanks that are heated via our geothermal superheater. It is incredibly efficient way to heat water,” she adds.

Rainwater + Hot Water Recirculation

John Morra of MCC Inc., in Point Pleasant, N.J., is designing a customized home automation system for a green home project, and is also planning some innovative water conservation measures via rainwater harvesting. Unlike most rainwater harvesting systems that use an underground tank, or cistern, this home will have four 1,500-gallon water tanks located in a crawl space.

The limited height of the crawl space precludes installing and servicing float sensors, so Morra plans to use sensor strips like those used in the tanks of boats.

Morra won’t be done there. He’s planning to use a water recirculation pump that’s tied to occupancy sensors in the bathroom, so when you enter and turn on a light, the cool water in the sink tap is pumped back into the water tank and replaced with warm water. As a result, you don’t have to wait for warm water as you waste gallons of cool water.

Affordable Systems?

In Mike McDonald’s very green “Margarido House” in Oakland, Calif., two 2,000-gallon rainwater harvesting tanks and an irrigation system provide 100 percent of watering year-round.

Water for landscaping also comes from the French drains around the perimeter of the foundation. This water is diverted back into the tanks. The Margarido House even pulls water from an underground stream.

Inside, a water recirculation pump circulates cool water back to the water heater so cold water isn’t wasted when waiting for warm. McDonald hits a button, and a D’mand recirculation pump circulates the cool water out and brings hot water to the tap. It’s about a 90-second wait.

McDonald’s company, McDonald Construction & Development, is also installing a gray water (from showers and washing) recycling system in a Northern California residence.

McDonald hasn’t done any ROIs on these systems, “But I think, other than the complex and expensive gray water system, all these simple solutions can easily pay for themselves quickly.”

Here’s a rundown from McDonald:

Rainwater Harvesting Costs (with a tank or cistern)

From super cheap ($500) if just capturing roof water from downspouts to something like a “rainhog,” to tens of thousands of dollars if installing underground tanks with sophisticated pumps and sensors.

Automatic Irrigation Systems

An excellent and inexpensive way to reduce water usage. Focus should be on “drip” irrigation vs. sprayer heads, and simple computer controlled timers that schedule watering early in the day or late at night. Cheap and helpful options include a “rain sensor” that shuts off a system if it detects rain.  An automatic irrigation system including piping, and control units, can be installed for less than $1,000 by a homeowner assuming a normal sized garden, lawn, etc.

Water Recirculation Systems (warm water at tap)

Are excellent and inexpensive ways to save water. They cost as little as $500 installed.  See example and savings.

Gray Water Re-use

This can be pretty complicated, expensive and have issues regarding local and state building codes.  We are currently installing a gray water/rainwater system on a single family residence project in northern California, and the total cost is more than $30,000. Here is a good research link.

Other Ways to Save H2O

  • Use low-flow showerheads and faucets.
  • Use 1.6-gallon or non-flush toilets (if you can stand the latter).
  • Choose WaterSense-labeled fixtures.
  • Buy an Energy Star-rated dishwasher.
  • Fix dripping faucets.
  • Wash dishes and clothes with full loads.
  • Practice xeriscaping (the use of native and low-water plants).

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