Here in California – and in many parts of the world – water scarcity is a way of life. Thankfully, most of the water that we use indoors can be safely reused for outdoor irrigation and toilet flushing. This is called grey water.
Grey water is used water from sinks, showers and washing machines. It makes up the majority of household wastewater. It has small amounts of chemicals from soaps and shampoos, but these are manageable during reuse. Surrounding soils absorb some of these chemicals, and plants can use others for food.
Waste from toilets, kitchen sinks and dishwashers is considered black water. Black water needs special processing, usually from a wastewater treatment plant, to be safe.
At Greywater Corps we specialize in grey water systems for irrigation. Most of our projects involve retrofitting single family homes to separate grey water from black water. We then set up systems to reuse that greywater to feed plants outside.
First, we get in the crawlspace under the house and modify the plumbing to separate grey water from black water. From there we install four types of systems, three of which use untreated, raw greywater, meaning no filters and very low maintenance. They are:
Laundry to landscape (L2L): this type of system uses the washing machine’s internal pump to move greywater. It can irrigate across level terrain or downhill.
Branched drain (BD): this system uses gravity flow directly from plumbing fixtures to move gray water. It can only irrigate downhill.
Pumped system (PS): pumped systems use a motorized pump to move greywater. They can irrigate uphill.
Untreated grey water is released in trenches 8 to 12 inches deep, filled with woodchip mulch. These trenches, called mulch basins, allow grey water to percolate laterally through the mulch without ever reaching the surface. Gray water is released inside valve boxes embedded in the mulch and filters out to the landscape from there.
Grey water is not ideally suited for lawns or other water-intensive landscaping, but it can be applied to a wide range of landscape designs and plant palettes, from verdant tropical reveries to riparian habitats shaded by sycamores, to edible gardens bursting with fruit. In low water gardens, grey water can be applied to key plants like fruit trees, shade trees and perennials. Grey water systems generate large amounts of water and discharge it all at once, so they are best paired with larger plants that can absorb it.
We also install advanced systems that use varying levels of treatment to clean grey water for applications such as drip line irrigation. These systems come with greater costs and maintenance, but also allow much greater flexibility and enhanced capabilities.
While most of our projects involve single family homes, we have also built systems at apartment buildings, schools, universities, hotels and more. Every building can find its own strategies to best manage this precious resource we call grey water.
Answered by Josep Ferrer, Greywater Corps
For more information visit our website www.greywatercorps.com.
To receive notices about future blogs, be sure to subscribe to Soils Matter by clicking on the Follow button on the upper right! Explore more on our webpage About Soils. There you will find more information about Soil Basics, Community Gardens, Green Infrastructure, Green Roofs, Soil Contaminants, materials for Teachers and more.