Did you know you can grow a beautiful garden even living in a desert like Las Vegas. Some households can cut their water bills almost in half by irrigating with greywater. That is a huge benefit. Now that large sections of the country are facing historic drought conditions — and the possibility that these droughts are the new normal — it especially doesn’t make sense to send usable water down the drain. You are probably irrigating your yard with drinking water, but do your plants need drinking water? It turns out that most plants are perfectly happy with gently used water from showers, bathtubs, laundry and sinks — or greywater. Most households use about half its water indoors and the other half outside for irrigation. You can recapture that water and use it again. There are other benefits to greywater, too. It reduces a home’s carbon footprint, since moving and treating water consumes a tremendous amount of power. It protects the aquatic ecosystems from whence your water comes. It reduces loads on sewage systems (which lowers the carbon footprint) and puts water back into the local aquifer, which is better than dumping it into rivers, lakes and oceans. If you’re on a septic tank, it reduces loads on the system, prolonging your service intervals. And it helps grow a beautiful and bountiful garden.
Greywater systems don’t look like normal irrigation. For one thing, there’s stuff in it — small amounts of soap, hair, laundry lint etc. You can either process the water and try to filter everything out, or you can use larger pipes and emitters and send the water to your garden as is. The latter is the better option — ideally, a greywater system should be low tech and dependable, with a minimum of parts to break and filters to maintain.
Setting up a greywater system involves:
1. Replumbing greywater fixtures away from the sewer.
2. Installing the greywater system itself and
3. Installing irrigation in the yard.
Basic Greywater Systems
Laundry-to-landscape system. The easiest place to start with greywater is the washing machine. Since the water comes out of a hose on the back of the machine, there is no need to alter the plumbing under the house. The most common washing machine system is called a laundry-to-landscape system, which uses the washer’s internal discharge pump to help move water out into the yard, where it is distributed into mulch basins through a network of ½-inch ball valves.
Branched drain system. A common greywater system for bathtubs, showers and sinks is a branched drain system. It’s a gravity-flow system with no storage tanks, pumps or filters; it relies on gravity and mulch to distribute water in the landscape. Drains from greywater fixtures are combined into a single pipe, which is diverted away from the sewer and outside the house.
Once outside, the flow is divided and subdivided into multiple branches to be spread to various outlets in the yard. Since the pipes need to flow slightly downhill, this system may not work on flat lots or if the area to be irrigated is above the house.
Here a worker levels the flow splitter of a branched drain system.
Sump-pump systems. If the areas to be irrigated are far from your house or uphill, you’ll probably need a pump. The best way to do this is with a sump-pump system: Greywater fixtures (bathtubs, sinks, showers and laundry) are rerouted to drain to a basin containing a submersible pump activated by a float switch that shoots the water out as soon as it gets deep enough. Remember that no freshwater irrigation system will work with greywater — it would rapidly clog — so distribution in the landscape should be similar to that of the laundry-to-landscape system: a network of tubing no smaller than ½ inch to allow the passage of suspended solids, distributing water into mulch basins.
Common Greywater Mistakes
Thinking you can water a lawn with it. Greywater is not potable and cannot be used in sprinkler systems. This makes almost all greywater systems incompatible with grass. Lawns in general use a tremendous amount of water; for folks considering greywater, we recommend tearing up the lawn and replacing it with native plants that don’t need external irrigation — then use greywater for fruit trees, shade trees, ornamentals and perennial vegetables.
Storing it. Greywater should not be stored in a tank. Trace amounts of organic matter will cause anaerobic bacteria growth and funky odors. It’s better to just put it in your soil immediately and thus eliminate any problems.
Overcomplicating things. Pumps and filters generally just mean more things that can break and that need maintenance. Don’t pump greywater if you can do the same job using gravity. Don’t install a filter system that involves routine cleaning unless you are willing to clean or replace it for the next 10 years. Consider the carbon footprint of the system: In cases with elaborate piping and pumps, the carbon footprint will never be offset by the water savings.
Partial Reprint from Houzz…..thanks