by Grit Leipert, AC Martin and David Summers, P.E., LEED AP Glumac
On September 1, 2009, a new era of water recycling began in Los Angeles, California. Grit Leipert, project designer at AC Martin and Frank Pasker, project manager at DBB Architects, obtained the first graywater permit in the Southern California metropolis. The graywater system services the future home of the two professionals: an experimental single family dwelling known as the Nob Hill Haus located in the eclectic neighborhood of Mount Washington.
Originally implemented in 1992, the city of Los Angeles had regulations for graywater systems in place for quite some time, but no one had previously managed to clear the high hurdles to obtain official approval to use the system within the city limits. Various issues needed to be considered, such as the safety of the potable water supply, groundwater depth, soils classification and the avoidance of human contact with graywater. All of these items have been addressed in this project, and the various city and county officials supported this idealistic project from the start.
One important factor which allowed a permit to be granted for the graywater system was the set of new regulations by the California Department of Housing and Community Development (HCD) approved on August 4, 2009. These regulations (the “Express Terms for Proposed Emergency Building Standards of the Department of Housing and Community Development regarding the 2007 California Plumbing Code [CPC] Calif. Code of regulations, Title 24, Part 5, Chapter 16A, Part 1 [Graywater Standards] ) are recognized by the city of Los Angeles and allowed the project to move forward.
These HCD regulations are similar to the 2007 CPC in many ways, yet there are some differences. One of the differences is that reclaimed water supply pipes used for irrigation can be buried at a minimum soil depth of 2 inches in the leachfield, instead of the 10 inches required by CPC. This is an important difference in allowing the reclaimed water to be delivered to the root zone of plants and to be an effective means of irrigation. Other differences include the ability to install a greywater system without a permit in limited applications. Further information can be found here.
In addition to using graywater as irrigation, other water-conserving features of the Nob Hill Haus project include dual flush toilets, low-flow faucets and a 1700-gallon rainwater storage cistern.
As California’s water supply shrinks every year amidst a steadily growing population, the use of water from showers, tubs, lavatories and laundry to irrigate yards will be a more and more sought-after feature in the future. Construction on the Nob Hill Haus started in September 2009, and the owners are looking forward to the moment when their first load of laundry waters their garden.