Split Drain to Mulch Basins or Mini-leachfields

For ideal situations with continuous downhill slope from the points of greywater generation to the points of irrigation need, this design promises inexpensive, reliable, efficient distribution WITHOUT FILTER CLEANING. It is critical that hard-plumbed lines have proper slope (at least 1/4" per foot)…

One way to split the greywater flow to accomplish wider distribution is to not combine the flows in the first place; each fixture waters its own area. Coordination with fresh water irrigation may be complicated by using this technique. It works best as primary irrigation, with each flow matched to an appropriately sized, established tree.

Another way to split the flow is by using "double ells" (Figure 3, page 13). If there are ridges on the inside of these fittings they must be ground smooth-a rotary file in a drill works well. The maximum number of splits is probably four, in "family tree" style. In theory, the water will split predictably so a single irrigation zone sensor would get a representative reading off of any outlet. The double ell variation is a brand new Art Ludwig design. I would appreciate hearing of your experiences with it. According to the folks in Sacramento, a local jurisdiction could interpret this system as conforming to the California greywater law requirements for a mini-leachfield system, or the "other means of distributing greywater subsurface clause," providing you could demonstrate that the effluent would not surface. As part of the inspection they might require you to run a surge into the system and check for surfacing before giving final approval.

The Builder's Greywater Guide includes the entire text of California's greywater law, with extensive annotations added to clarify the implications and possible ways to get a practical system through the cracks. It also includes two pages of needed improvements to California's greywater law.