Use grey water in your garden

With the focus on being more water wise in our gardens, why not consider using the ‘grey’ water that is produced by your household? Which water can you use? On which plants should you use it? And what are the repercussions for your garden? Watering, along with composting, feeding, mulching and so on is a vital component in successful gardening. During prolonged dry periods, where water is at a premium, gardeners may want to make use of ‘grey’ water to keep their gardens alive.

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Grey water or second-hand household water is water from the bath, shower, washing machine, etc. Of vital concern to gardeners is the level of salts, chemicals, soaps and fats that grey water may contain, and its effect on their gardens. Prolonged use of most grey water is not recommended in the garden as it does affect the soil and health of plants. But desperate times call for desperate measures, and grey water can be used, if a number of factors are taken into consideration.

Grey water used over a long period in the same position will ultimately damage the soil, causing the build-up of salts and deflocculation (finer soil particles filter downward), leaving the surface of the soil barren and sandy and low in beneficial micro organisms. For this reason, outlet pipes should be moved around to different parts of the garden, to spread the load.

grey 2The quality of grey water is a major concern. Bath and shower water, and rinse water from washing dishes by hand, is the best grey water to use, as it contains the least harmful chemicals. It can be used on most plants with little negative affect. Washing machine water (particularly from the first rinse) and dishwasher water should only be used on well established trees and large shrubs, or lawns, as it contains harmful chemicals and fats that could have hazardous effects on the plants and also the soil. The key to using grey water is to filter it first (remove hair and other matter) and to allow it to stand for a while (a few hours) for sediment to settle. Keep grey water away from very sensitive plants such as roses, seedlings, ferns, orchids and delicate plants. Choosing safer, biodegradable or organic soaps and chemicals will also be a great help.

There are a number of very practical grey water systems on the market today. Most of them filter, collect and pump grey water out into the garden. Hire a plumber to connect them, and adjust all your plumbing to suit. Grey water in the garden is a great way to save water, the environment, as well as your garden.

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