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RAND WATER EDITORIAL

CONSTRUCTED WETLANDS

AS TREATMENT SYSTEMS FOR

HOUSEHOLD GREYWATER

BY SAMANTA STELLI AND LESLIE HOY, RAND WATER

outh Africa is a semi-arid country
with variable rainfall patterns, and
Sfreshwater sources are under threat
from over-use, pollution and the effects of
climate change. Climate change indicates
further extreme weather events (floods and
droughts), drier conditions in typically dry
regions, wetter conditions in typically wet
regions, as well as temperature increases.

Another significant impact on the country’s
water resources is old, poorly maintained
and leaking infrastructure, which has
resulted in large volumes of non-revenue
and wasted water. South Africa is the 30th
driest country in the world.

Alternative sources
Alternative sources of water such as
greywater re-use, treated effluent,
water recycling, desalination, rainwater
harvesting, and extraction of groundwater
are some of the new approaches being
considered to address water needs.

Up to 70% of water used in the household Crinum bulbispermum is an indigenous plant The Water Wise Guide to DIY Constructed
can be re-used as greywater, which is that works well in a constructed Wetland Wetlands. Download for free from the
wastewater derived from domestic and Water Wise website.
household use of water for washing,
laundry, cleaning and food preparation simply with DIY systems. The latter includes Constructed wetlands to treat
and does not contain faecal matter. using buckets in the shower to catch water greywater
Greywater from the laundry, shower, bath run-off, directing laundry water into the Water Wise has developed a simple
and hand basins is preferable for use over garden or collecting bathwater for re-use. solution to treat domestic greywater for
kitchen sink or dishwater, as the latter may Greywater can be used for activities that do use in the landscape. This constructed
contain grease, oil, blood or food scraps. not require potable water such as cleaning wetland system is designed for garden
Greywater can be harvested with complex hard surfaces, flushing toilets and irrigating and urban landscape use and can be
harvesting and treatment systems, or very gardens. adapted to suit the volume of greywater
produced. The design ensures that there
is no pooling of greywater on the surface,
no smell or water-borne pests such as
mosquitoes. A constructed wetland
is man-made and mimics the natural
process of a wetland to treat water.
Greywater is passed through the wetland,
where it is slowly cleaned, filtered and
then released. The root system of the
plants releases oxygen into the water,
creating a suitable environment for
aerobic, microbial and fungal activity
(biological breakdown of pollutants and
organic materials).

Besides removing contaminants from
domestic greywater such as oil, grease,
phosphates and sulphates, the system
significantly decreases the levels of
coliform bacteria in greywater. An
A flourishing constructed wetland
at Rand Water, using greywater from
22 Landscape SA • Issue 116 2022 the kitchen and bathroom basins.