The Green Dream: Going Gray, Saving Blue

A graywater system uses shower and sink runoff to flush the toilets. Plus: four more ways to save water at home    

By John B. Carnett

Green Dream: The Specs House: 3,500-square-foot, four-bedroom contemporary Location: Greenwich, N.Y. Project: Install graywater recycling Cost: About $2,600 ($1,400 for the system; $1,200 for plumbing) Time to install: 2 hours Eco-advantage: Uses household runoff for toilets, saving water and work for the septic systemPeter Bollinger

Just because residential water is cheap and plentiful here in upstate New York is no reason to waste it, and the average household does plenty of wasting: A single flush consumes three to seven gallons of water. Inefficient toilets and long showers are two of the biggest water wasters, together accounting for more than 40 percent of the 350 gallons of water used daily in a typical American home. But my eco-home is anything but typical—its graywater recycling system can save at least 110 gallons a day.

Graywater refers to the runoff from sinks, showers and washing machines (as opposed to blackwater, which contains solid waste). With some basic plumbing and a storage tank, it’s easy to recycle that water to flush my house’s four toilets. By using the water twice, I’ll also save wear on my septic system.

The setup is pretty straightforward. Water from the bathroom sinks and showers goes through a chlorination filter and into a holding tank, where it can be pumped to the toilets. (I’m skipping the washing machine and kitchen sinks, since they require additional filtering and I’ll recycle plenty of water from the bathrooms alone.) It’s not difficult to DIY, but the central challenge is monitoring and controlling the level of chlorine in the storage tank. Too little, and you’ll get bacteria in the tank. Too much, and it will kill the bacteria your septic system needs. So I’m using a new setup from a company called Blue Eco Systems that funnels water through a chlorinator to carefully control how much chlorine goes in. Carbon filters on the overflow and bypass lines prevent chlorine from getting back into the septic tank and the toilets, lest my bathroom smell like a swimming pool.

The system uses a pair of 25-gallon tanks—enough for my family of four—but I can easily expand it with more tanks if we have more kids or the in-laws move in.

How It Works: Green Dream: Peter Bollinger

How the Green Dream's Plumbing Works

Fresh water in: If there’s not enough graywater in the tanks for a flush, the system pulls in regular street water.

Graywater in: Water coming from bathroom sinks and showers

Graywater to Toilets

Carbon filters: Remove the chlorine from the water before it reaches your toilet or septic system so it doesn’t kill the bacteria the septic system needs
Chlorinator: Cleans the graywater to prevent bacterial growth in the tank

Vent

Overflow: Carries extra water out to the septic system so the tank doesn’t overflow
Pump: Sends the water from the tank up to the toilet tanks
Flow sensor:If the system detects no water flow in 22 hours, it dumps the contents of the tank so it doesn’t sit long enough for any remaining bacteria to grow.

Four More Ways to Save Water at Home

Sprinkler Shutoff
A broken sprinkler can waste 100 gallons in 10 minutes when the irrigation system kicks on in the early-morning hours. This automatic shutoff valve prevents waste by holding water in the irrigation tubes if the sprinkler head is broken, saving about 65 percent more water than a system without one. From $4; dry-planet.com

Greener Grass
Most grasses in America are indigenous to Europe, so they need more water and maintenance. The University of Nebraska is developing a new type of buffalo grass, native to the U.S., that will require between 40 and 75 percent less water than foreign species like blue grass or fescue. It will be available next January. From 50 cents per sod plug; toddvalleyfarms.com

Low-Flow faucet
Install Niagara Conservation’s simple aerator in your bathroom, and choose among three flow rates—0.5, 1.0 or 1.5 gallons per minute—depending on your task. All three settings use less water than the standard 2.2-gpm fixture, and the lower two even best the EPA’s 1.5-gpm high-efficiency faucets. $11.50; niagaraconservation.com

John B. Carnett, PopSci’s staff photographer, is using the latest green technology to build his dream home. Visit popsci.com/greendream for John’s blog.


Source: Popsci