BRANCHED DRAIN GREYWATER SYSTEMS
This classic system harnesses the power of gravity to irrigate areas downhill from the home. Its simplicity makes it easy to maintain, but also less flexible.
SYSTEM OVERVIEW
The Branched Drain system is the ultimate in simple, low- tech greywater systems, designed for decades of trouble-free irrigation. There are no filters to clean or change, no storage tanks, no pumps, and no controllers to program. The system relies on natural processes: gravity, capillary action, microbes in the soil – to distribute and process greywater in the landscape. The only control is a single on-off switch.
PHASE 1: DUAL PLUMBING & DIVERTER VALVE
Drain lines from greywater fixtures in the house (bathtubs, showers, bathroom sinks and washing machines) are reconfigured to drain to a diverter valve, which can send water to either the sewer or the greywater system (this allows the user to “turn off” the greywater system if needed, for example if doing a load of laundry with bleach).
IRRIGATION INSTALLATION
Irrigation is through a network of flow-splitters and underground emitters that divide and subdivide the flow, spreading it out in the landscape. Emitters are subsurface, each set in a protective valve box enclosure within a mulch basin – a trench filled with wood chips that act as a medium for greywater distribution and allow greywater to percolate out laterally. The wood chips are an organic greywater filter, catching laundry lint and soap and breaking down impurities through natural microbial action.
DESIGN & PERMITTING
Greywater Corps staff includes landscape designers, permaculturists, plumbers, irrigation experts, and a licensed architect. We take pride and care in the appearance (or disappearance) of our systems. We are one of the few greywater installers who can also produce stamped drawing sets, pass plan-check and pull permits – in fact, we helped write the city of LA greywater code. Greywater Corps’ background in architecture and years of experience make us uniquely qualified to prepare drawings and shepherd them through the permitting process.
MAINTENANCE
Maintenance is minimal and can be handled entirely by Greywater Corps, generally with one visit per year. Systems are designed for easy access & servicing. There are no filters, pumps or storage tanks to clean or replace. Wood-chip mulch beds are a vital component of the system and should be replenished every few years as they subside and turn into rich, healthy soil.
DESIGN PRINCIPLES
Our approach to ecological systems design is that of appropriate technology: small-scale, low-tech solutions that avoid over-engineering in favor of simplicity and natural processes. For example, using gravity and capillary action to distribute greywater and mulch to filter it.