Use Greywater Irrigation to Reduce Your Water Needs

Water is a precious resource, and not just in developing nations. the West coast of America regularly suffers drought conditions, Australia has only just emerged from a drought which lasted over a decade; and even in the UK, changing rainfall patterns have meant that parts of the SE England are in drought. But every day each of us pours away gallons of water from baths, showers and laundry. This greywater is not fit to drink, but it’s certainly good enough to water the garden, and more and more people are turning to simple greywater irrigation methods to save valuable drinking water and reuse perfectly adequate greywater.

Greywater Irrigation

Why wouldn’t you use greywater on your garden? There has traditionally been a ‘yuk’ factor around putting dirty water on plants, especially ones you might eat, such as salad vegetables. Indeed, some states have even prohibited its use. But these opinions are changing in the face of facts and necessity. Greywater is perfectly safe to use on trees and flowers, and is safe to use on most vegetables as long as it doesn’t splash onto the leaves you eat (always thoroughly wash raw veg). And in the face of ever-rising water consumption, some countries are now actively promoting greywater irrigation.

So what’s the best method to irrigate your garden with greywater? At its simplest you can just fill a bucket from your bath. This is fine for small volumes of water, but carrying heavy buckets of water through your house is hard work, time consuming and potentially an accident waiting to happen. Alternatively you can divert the waste water pipe into a water butt and collect your greywater for reuse. But don’t leave the water to stand for longer than 24 hours; greywater is a potent cocktail of bacteria, dead skin and detergents, mixed in a warm bath. It soon starts to smell like a sewer, so reuse as soon as possible.

It’s not advisable to pump laundry water directly onto your garden from your washing machine. The pump is designed for this type of work and can easily be damaged under the excess load.

You should also consider the efficiency of just pouring a load of water onto the soil. Much of it will run off and be wasted (as much as 80%)[1], so if time allows, use a watering can (although not on vegetables for the reasons above).

In order to maximize the amount of water going into the soil, dripper lines buried under a small layer of mulch are probably the best option. A dripper line is a hosepipe with holes punched in it. Water flows through the pipe and leaks from the holes at a low flow rate, so the water has time to percolate into the soil. As it’s buried under mulch, very little is lost to evaporation. A basic system can be built from a water butt, which collects greywater; the hose is connected at the bottom of the butt, and a filter collects any debris. The hose is then laid under mulch around the garden, and gravity forces the water through the hose. For larger systems, a pump can be installed.

These methods are simple, low cost solutions to the double whammy of our increasing demand for water whilst at the same time living with increasingly regular drought conditions

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