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March 20, 2019

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Greywater guidelines for home gardens in Gauteng

1. Introduction
2. What is greywater?
3. Greywater quality
4. Greywater re-use
5. How to use greywater
6. Greywater re-use rules
7. Greywater systems
8. References


The human race needs water to survive, to work, to eat, to live healthily and to participate in recreation. These activities have resulted in the Earth’s water becoming scarce and polluted
as water is used at an alarming rate. The global population increase is placing demands on all natural systems and as pressures on available water increase, so more measures are required to supply water to users. Researchers generally state that between 2015 and 2033, the water demand in South Africa will exceed supply and the supply will not be able to cope with the anticipated population growth, consumption and other needs for water. This pressure is exacerbated by the fact that South Africa is a water scarce country and only receives an average of 492 mm per annum (Fig 1).


Fig 1 . Mean annual precipitation map for South Africa.


The majority of summer rainfall areas in South Africa and specifically the Gauteng area have had 16 consecutive years of above-average rainfall, barring the summer of 2014, and the last major drought was almost more than two decades ago. This helps to create a false sense of water security.


In South Africa, municipal water use, which includes domestic
water and water used in the garden, is indicated at being 27%
of the total water used. A major component of domestic water
consumption is gardening, estimated at 31-50% of the total
water use. The use of water for gardening could be reduced
drastically if homeowners implement the following initiatives:

   • use of water-wise gardening concepts and droughtresistant
indigenous plants;
   • mulching of soil to preserve soil moisture;
   • efficient irrigation systems and irrigation scheduling;
   • rainwater harvesting and
   • the reuse of wastewater (greywater);
   • Soil improvement processes e.g. composting.


Greywater presents a potentially suitable water resource
that can be used for irrigating certain plants such as flowers,
shrubs, trees and lawns in home gardens.


Greywater is wastewater (used household water) collected
from handbasins, showers, baths, washing machines and
kitchen sinks, but excludes water collected from toilets.

   1. Laundry water contains soaps, detergents, bleaches,
water softeners, lint, dirt and small amounts of skin or
faecal matter from clothes. Recently, many detergents
have become biodegradable and safe to the environment.
This water is suitable for irrigation use if your detergent is
   2. Kitchen sink or dishwasher greywater may contain soap,
detergents, grease, oils, blood, small traces of pesticides
and food scraps. It should not be used for irrigation unless
the water does not contain grease, blood, pesticides or
   3. Shower and bath water contains small amounts of soaps
and shampoo as well as hair, skin, oil, faecal matter and
urine, but can also contain residues of cleaning products.
This water is suitable for irrigation use.
   4. Handbasin water can contain soap, toothpaste,
mouthwash, hair and shaving cream as well as residues of
cleaning products. This water is suitable for irrigation use.


Greywater from the bathroom (handbasin, shower and bath)
presents the best source of greywater for irrigation where
greywater is separated by source, as it is considered to be
the least contaminated of all the greywater in the home.
Water from your toilet, which is considered black water, is not
suitable for any reuse in or around your home.