In order to save money and eat higher-quality food,
many people are turning to growing their own vegetables. I am certainly part of
that group! I look forward to this time of year but honestly, the considerable
water use has always bothered me (and my bank account!).
Like me, you are probably irrigating your yard with
drinking water, since the same water that comes out of your kitchen faucet also
comes out of your hose. But do your plants need drinking water? It turns out
that most plants are actually perfectly happy with gently used water from showers,
bathtubs, laundry and sinks: say hello to greywater!
Greywater (also “graywater") is water that has
been used for washing dishes, laundering clothes, or bathing. Essentially, any
water other than toilet wastes that drains from a household is considered greywater.
Greywater may contain traces of dirt, food, grease,
hair, and certain household cleaning products. While greywater may look dirty,
it is a safe and even beneficial source of irrigation water in a yard, and is suitable
for irrigating lawns, trees, ornamentals, and food crops. Keep in mind that if
greywater is released into rivers, lakes, or estuaries, its nutrients become
pollutants, but to plants, they are valuable fertilizer.
Aside from the obvious benefits of saving water (and
money on your water bill), reusing your greywater keeps it out of sewers and
septic systems, thereby reducing the chance that it could pollute local water
bodies. Reusing greywater for irrigation also reconnects urban residents and
our backyard gardens to the natural water cycle. This system works well as the
average American household uses about half its water indoors and the other half
outside for irrigation. Some households can cut their water bills almost in
half by irrigating with greywater.
The easiest way to use greywater is to pipe it
directly outside and use it to water ornamental plants or fruit trees.
Greywater can also be used to irrigate vegetable plants as long as it doesn’t
touch edible parts of the plants. In any greywater system, it is essential to
use “plant friendly” products, those without salts, boron, or chlorine bleach.
The build-up of salts and boron in the soil can damage plants. Watch out for
your own health as well: “natural” body products often contain substances toxic
Greywater is different from fresh water and requires
different guidelines for it to be reused:
- Do not store greywater for more than 24 hours. If you store greywater the
nutrients in it will start to break down, creating bad odors.
- Minimize contact with greywater. Greywater potentially contains pathogens if an
infected person’s feces got into the water, so your system should be designed
for the water to soak into the ground and not be available for people or
animals to drink.
- Infiltrate greywater into the ground. Do not allow it to pool up or run off. Knowing
how well water drains into your soil or the soil percolation rate of your soil
will help with proper design. Pooling greywater can provide mosquito breeding
grounds, as well as a place for human contact with greywater.
- Keep your system as simple as possible. Avoid pumps and filters that need
upkeep. Simple systems last longer, require less maintenance and energy, and money.
- Install a 3-way valve for easy switching between the greywater system and the
- Match the amount of greywater your plants will receive with their irrigation
of Simple Greywater Systems
the Washing Machine:
Washing machines are typically the easiest source of
greywater to reuse because greywater can be diverted without cutting into
existing plumbing. Each machine has an internal pump that automatically pumps
out the water – you can use that to your advantage to source the water directly
to your plants.
If you are looking for a system that requires little
maintenance while giving you flexibility in what plants you are able irrigate,
I recommend the laundry-to-landscape system. This system was invented by Art
Ludwig. This greywater system does not alter household
plumbing: the washing machine drain hose is attached directly to a diverter
valve that allows you to switch the flow of greywater between the sewer/septic
and the greywater irrigation system. The greywater irrigation system directs
water through 1? tubing with 1/2? outlets pumping water to specific plants.
This system is low-cost, easy to install, and allows for flexibility in
irrigation. In most situations this is the best place to start when choosing a
Showers are great sources of greywater- they usually
produce a lot of relatively clean water. To have a simple, effective shower
system, consider a gravity-based system (no pump). If your yard is located
uphill from the house, then you will need to have a pumped system.
Kitchen sinks are a source of a fair amount of
water, usually very high in organic matter (food, grease, etc.). This water
will clog many kinds of systems. To avoid clogging, it is recommend to use a
branched drain system with mulch basins: organic matter will collect in the
woodchips and decompose. Since bathroom sinks do not typically generate much
water, they often combine flows with the shower water. Or, sink water can be drained
to a single large plant or divided to irrigate two or three plants.
Low-tech, simple greywater systems are best suited
to specific, large plants. Use them to water trees, bushes, berry patches,
shrubs, and large annuals.
Warm-up water is all of that water that goes down
the drain as you are waiting for the hot water to reach the faucet or shower,
which can be quite a bit if your water heater is located far away from the
point of use. To capture and use warm-up water, simply put a bucket or large
bowl under the faucet when you turn on the hot water then move it out of the
way when the water is hot. That water can be used to directly water house or
garden plants, as it is just as clean as the rest of the tap water that gets
used for those tasks.
Evaluate the ideal method of greywater reuse for
your specific wants and needs. If you are considering implementing a greywater
system at your home, be sure to thoroughly consider your options and perhaps
consult with a greywater professional.
One final but crucial point: the rules and regulations regarding greywater
reuse vary quite a bit, so depending on your location, some or all of these
ways of reusing greywater may be illegal. In addition, improper management of
greywater can lead to odor, pest, or pathogen issues, so it is vital to do research
before putting in any sort of greywater system!