Greywater is the waste-water generated from the home, excluding toilets, which is known as blackwater. Greywater makes up 50-80 % of residential water usage, and can be reused for irrigation and constructed wetlands, as well as toilet flushing and laundry. Greywater systems can significantly reduce water usage while increasing your ability to grow and irrigate plants.
Elements of a Greywater System
1. Greywater source: Shower, washing machine, sinks, etc.
2. Collection plumbing: Pipes that transport greywater from the house to another point outside the house.
3. Surge tanks, filter, pump: Optimal elements that facilitate distribution, but not required.
4. Distribution plumbing: Pipes that transport water to yard and plants.
5. Receiving landscape: Mulch basins and plants that receive the water.
Quality and amount of greywater varies depending on the source. Washing machine, dishwasher, and sink greywater can use non-toxic DIY cleaning products.
- Washing Machine: Good quality, 85-100 gal (320-380 L)/person/week
- Dishwasher: Poor quality, 5-10 gal (20-40 L)/load
- Shower: Excellent quality, 70-100 gal (260-380 L)/person/week
- Tub: Excellent quality, variable use
- Bathroom sink: good quality, 7-35 gal (26-130 L)/person/week
- Kitchen sink: good quality, but food scraps create anaerobic potential, 5-15 gal (20-55 L)/person/week.
- Toilets: Very bad; do not use.
While there have not been any documented cases of greywater transmitted illness in the United States, greywater may contain infectious and pathogenic organisms. There are two main design principles needed to ensure safety:
- Greywater must pass slowly through healthy topsoil for natural purification to occur.
- Design you greywater system so that no greywater-to-human contact occurs before purification.
Easy to Create Systems
There are a few cheap easy-to-install greywater systems that do not require complex filtration or pumping systems, as long as you meet the above two health considerations. In order to drain water and solids at the same speed, preventing clogging, it is necessary to maintain as close to a 2% downhill grade as possible.
- Outdoor Showers: Outdoor showers are a cheap, easy, and enjoyable way to apply greywater to specific trees.
- Drain to Mulch Basin: Sending water straight down a drain, out of the house, and to a nearby mulch basin is easy to cheaply install.Trees located near the house can provide shade, regulate high and low temperatures, and provide an edible yield.
- Branched drains: Branched drain greywater systems build on the drain-to-mulch basin by splitting the flow into various sections. Only possible for sites that drain downhill, branched drains create a low maintenance distribution system. Splitting up to 16 different outlets has been successfully achieved.