HEALTH AND SANITATION
47
"The most common use for
greywater currently is for
garden irrigation, and limited
use on vegetables that require
significant processing prior to
consumption such as cooking."
greywater. This is to prevent environmental degradation
and reduce exposure of the population to health risks.
The most promising domain for institutionalising
greywater reuse appears to be in large buildings
such as office blocks, public buildings, and hostels.
Greywater can be collected and treated under proper
supervision and the large amount of (usually) lightly
contaminated water originating from such buildings can
be used for irrigation of gardens and sports fields, toilet
flushing, and so on.
Samples for the testing of Escherichia coli were taken from
the same eight houses as the nutrient samples on the
day of the third test. It was evident among the interviewed
participants that there were similarities in the way home-
owners use, perceive, treat, and manage greywater.
The water thus saved can make a significant difference,
especially during times of water scarcity. If this is to
happen, however, the adaptation of building codes for
such buildings should be investigated as a matter of
priority. The potential to use greywater for a specific end-
use is dependent on how and from where the greywater
is collected, stored, treated (if at all), and used.
Specifically, 95% of the participants were happy with
how their greywater has kept their gardens green
and reported no concerns to human health. Only one
participant removed their system due to foul odours.
It was also found that each household had the same
primary sources of greywater attached to their system:
baths, shower, hand basins, and washing machines.
CASE STUDY: GREYWATER USE IN FORMAL
HOUSING, CAPE TOWN
A short investigative study was undertaken in Cape
Town during 2016, to try and determine how greywater
is currently being used and managed in typical upper-
income homes, the attitudes of the people towards using
these greywater systems, and an indication of some of
the health risks that may result.
In each case, greywater is stored and flushed from
the greywater chamber on a daily basis and is used to
irrigate lawns, flower beds, fruit trees, and vegetable
gardens. Only a handful of respondents indicated that
they would not use greywater to irrigate edible plants.
Those who do use greywater to irrigate vegetable
patches, explained that they were conscious of the
household products they use to wash and clean. These
users would avoid acid-based detergents and rather opt
for organic, eco-friendly, and biodegradable products.
All the respondents made use of the same type of
proprietary greywater diversion device (GDD), which
is designed to divert laundry and bath/shower water
to a small storage chamber for immediate disposal
by irrigation. A randomised sample was selected
from a population of 893 homeowners in the study
area using a non-probability approach to identify
participants — all of whom have had a greywater
system installed in their home. Semi-structured
interviews were used to elicit information about the
way that the home-owners used and managed their
greywater systems.
The sampling of greywater was a useful indicator of
hazardous nutrients and contaminants, even though the
sample size was small. These contaminants either enter
the system directly through the sources (that is, faecal
matter through the laundry greywater), or develop within
Reedbeds simulate the function of
natural wetlands and assist in the
cleaning process of wastewater.
Here a gravity-fed system flows
through two reedbeds before
reaching the storage tank.
Continued on page 49 >>
Eight different houses were then sampled for greywater
quality analysis, in which water was sampled over three
different days, and a total of 24 nutrient samples were
collected. These samples were taken from the greywater
tank / chamber at the same time each day and stored in
dark glass bottles, at room temperature.
www.plumbingafrica.co.za
The themes most commonly raised were: the financial
benefit of the system, the year-round flourishing gardens,
few concerns about exposure to greywater, perceptions
about the quality of the greywater, and the ease of use
when operating their greywater system.
November 2018 Volume 24 I Number 9