Used water with a second life

Greywater is gently used water from showers, baths, bathroom sinks and clothes washers. It has some soap, lint, skin cells and dirt in it. It does not contain toilet waste.

Blackwater is water from toilets. Many codes also count kitchen sink and dishwasher water as blackwater, because food scraps and grease feed germs.

Greywater can be a large share of indoor use. Reusing it to water plants can cut outdoor water use, and it puts less load on a septic system.

Grey or black

Why greywater needs care

Greywater is not clean. It can carry germs from skin and clothes. Stored warm, those germs multiply within a day or so, and the water starts to smell.

That is why most rules and guides share a few basics:

• Use greywater soon. Do not store it for more than about 24 hours.
• Send it below mulch or soil, not into the air. No sprinklers or sprays.
• Keep it out of reach of people and pets, and away from wells, streams and property lines.
• Do not let it pool or run off your land.
• Do not put it on the parts of food plants you eat, especially root crops and leafy greens.

Simple ways to reuse it

The simplest systems use no pump and no tank.

• Laundry-to-landscape: the clothes washer’s own pump sends water through a hose or pipe to mulch basins around trees and shrubs.
• Branched drain: gravity carries shower or sink water downhill, splitting it between several mulch basins.
• Mulch basin: a shallow pit filled with wood chips around a plant. Greywater soaks in below the surface, where soil life breaks it down.

Fruit trees, shrubs and large perennials suit greywater best. Their roots spread wide and the fruit is far from the water.

Soaps and what goes down the drain

What you put down the drain ends up in your soil.

• Choose soaps and detergents low in salt and free of boron. Salt builds up in soil and harms plants over time.
• Avoid bleach and harsh cleaners when greywater goes to plants. Divert those loads to the sewer or septic.
• Use a simple valve that lets you switch the flow back to the sewer or septic. You need it in wet seasons and when plants do not need water.

What the rules allow

Greywater rules vary more than almost any other homestead topic. A few states make simple systems easier. California lets a laundry-to-landscape system skip the construction permit if it meets set conditions. Arizona lets a home use under 400 gallons a day without applying for a permit, as long as it follows the state’s rules. Other states require a permit for any system. Some do not allow greywater reuse at all.

Model plumbing codes, including the Uniform Plumbing Code, have sections on alternate water sources. Your state and county decide which rules apply.

Ask before you build. An illegal system can cause trouble when you sell, refinance or get inspected.

Pro and permit

Check

Summary

• Greywater is used water from showers, baths, bathroom sinks and laundry. Blackwater is toilet water, and often kitchen water.
• Use greywater soon, below mulch or soil, on trees and shrubs, never sprayed.
• Simple systems like laundry-to-landscape and branched drains need no pump.
• Rules vary widely by state and county. Ask before you build.

Next, you will build your own water budget and size a catchment system.