Conserve water: Apply water directly to plant roots, use waste for irrigation

Water management


When water is scarce, you need to make the most of every last drop.  You can conserve water by applying it directly to plant roots, and by using waste water for irrigation. In times of drought, farmers have to struggle to make the most of every little bit of water.  Nothing can be wasted.  Here are two tips on how you can conserve moisture and keep your gardens green.

The first way is to apply water directly to the plant roots.  The second is to use waste water for irrigating your crops.

Applying water directly to the plant roots: Let’s talk about how to water plants efficiently.  Only a small part of the water that falls on a field actually reaches the plants’ roots.  Maybe only two drops out of every 100 drops reaches the plants’ roots.  The rest of the water is lost through evaporation or runoff.  Here is a way to get more water to the roots, where the plants can make use of it to grow.  Use drip or pitcher irrigation.

You can make drip irrigators from jars, tins, or plastic bottles.  Clean the containers, especially if they are oily.  Make four tiny holes near the base of the container using a thin hot needle.  Partially bury the containers, with their lids on, between the rows in an upright position.  Sink the containers into the ground to a depth of between 5 and 15 centimetres, depending on whether the plants have shallow or deep roots.  Then plant seeds or seedlings.

While the seeds are germinating, water gently on top of the soil.  Once the plants are well established fill the containers with water once a week or as needed.  The water will drip slowly through the holes in the bottom deep into the soil close to the roots.

Porous, that is, unglazed, clay pots also make good drip irrigators, because water can pass through the pots into the soil. You can use clay pots the same way you use the other containers.

Add some liquid manure or compost tea to the containers once every week.  Adding manure or compost tea to the water makes it a nourishing drink to the plants.  It also slows down evaporation.

Using waste water for irrigation: The second way to conserve water is to make sure that water used for other purposes is also used for plants.  You can irrigate your crops with water that has been used for bathing, washing dishes or washing clothes.  Waste water is also called grey water.  Too much soap is bad for plants.  Therefore, use rinse water and not the initial soapy water.  However, soapy water which is free from harmful chemicals could be used on large trees and shrubs.

Here are some hints on using waste water:

  • Wash dishes in a basin and not in the sink itself.  Be sure to clean the dishes of grease and food remains before washing them.
  •  If you wash your dishes in the sink, place a bucket or bowl below the sink.  Disconnect the U‑shaped tube under the sink.  The grey water from the outlet will flow into the bucket.
  •  When you take a shower, take a bucket with you into the shower for catching water.
  •  After having a bath don’t pull the plug.  Get a bucket or bowl to carry the water to your garden.

Waste water cautions: Using waste water is a good way to conserve water, but you need to be careful about how you use it, or it could do more harm than good.  Here are some waste water rules:

  •  Use grey water only for well‑established plants.  Well‑established plants can resist impurities like     soap and oil better than young seedlings and germinating seeds.  Use only clean water on the        young seedlings and germinating seeds.
  •  Grey water is alkaline.  Therefore, do not use it on acid‑loving plants like citrus.
  • Do not let grey water touch the leaves of plants.  Be sure to apply it to the base of the plants only.
  • Do not use grey water around leafy vegetables or root crops. If you are practising drip irrigation in your garden, use only clear rinsing water.
  • Alternate grey water with clean water straight from the well or tap when watering.
  • Areas receiving grey water should be covered with thick mulch.  Mulching reduces evaporation of water.
  •  Products containing bleach will harm plants.  Never water your plants with water that contains bleach.

Information sources

“Gardening in times of drought,” published by Food Gardens Unlimited, P.O. Box 41250, Craighall, Johannesburg 2024, South Africa.