Putting Water in its Place
Water in the Southwest may be worth more than gold. Even growing the hardiest of native plants requires considering how they will be watered. In our backyard I've used rain barrels for two years to water the vegetable garden. But until now my front yard was dependent on direct rainfall and the garden hose. I've finally added a branched drain system that directs rainfall from the gutters to mulch-filled basins that water our trees and perennials. Hopefully, I can water the front landscape without moving a hose again!
Why did I go to the trouble of installing a rain and grey water infiltration system? First, it's 'free' water that I can either use or throw away. With a local average of 14 inches of precipitation annually, 'throwing away' water is at best foolish. Secondly, the existing drain system was broken, one side sent water to the storm sewer (wasteful), on the other side water pooled near the foundation (potential damage). Following examples provided by Art Ludwig and Brad Lancaster I redesigned two drains to direct water into four mulched basins that allow rainfall to soak in to the soil and be taken up by plant roots. Both branched drains were simple to build, use inexpensive ABS pipes and connections from the hardware store and should require very little maintenance.
I'm also planning to add grey-water to one branched drain, supplementing our inconsistent rainfall. Our washing machine is located near one of the branched drains so adding a connection should be a simple task. Grey water is “untreated household wastewater that has not come in contact with toilet waste and includes wastewater from bathtubs, showers, washbasins, clothes washing machines and laundry tubs, but does not include wastewater from kitchen sinks or dishwashers or laundry water from the washing of material soiled with human excreta, such as diapers”. New Mexico has allowed residential-scale (<250 gallons/day) gray-water systems without a special permit since 2003.
Update: Thanks to a rain shower today the branched drains are tested and they work! Now more rainfall is directed to our front yard plants and grey water will soon follow. These 'free' sources of water will reduce our need for city tap water and the associated water bills. This should also reduce our carbon footprint, though calculating that difference is a challenge.
In the meantime, reducing the need for treated and piped tap water is growing rapidly across the Southwest. The Lake Mead Reservoir is at the lowest level in 75 years. If that isn't warning enough, "National Center for Atmospheric Research (NCAR) scientist Aiguo Dai’s study indicates that most of the western two-thirds of the United States will be significantly drier by the 2030s." A drier future is knocking on our door so let's get ready for it.
More Info:
OasisDesign.net - Branched Drain Greywater Systems
Rainwater Harvesting for Drylands and Beyond by Brad Lancaster
New Mexico Environment Department - Gray Water Irrigation Guide
NY Times - Lake Mead Hits Record Low Level
Climate change: Drought may threaten much of globe within decades
