Water recycling
a certified plumber can retrofit an existing toilet. It is so much
easier if reuse is included in the design and construction of the
building.”
Interestingly, Dr Ilemobade says that greywater for irrigation and
gardens is the most popular use for minimally treated greywater
(from bathing and laundry).
These sieves are cleaned once a week. Two chlorinators disinfect
the greywater to kill any micro-organisms. The greywater tank was
kept small in order to ensure that the water is used immediately.
The tank has two submersible pumps for directing water to the toilet
when the toilet is flushed, using a switch within the toilet cubicle.
Necessary measures were also put in place to avoid backflows.
Beneficial project
“If accepted by South African municipalities, the project will be
beneficial to many water scarce communities, said Dr Ilemobade.
“At this stage the reuse of black water (sewerage) is not considered
due to the potentially higher public health risks.”
The start of the pilot project was boosted by a massive user
awareness campaign at WITS, UJ and UCT. This promotion was
met with a high level of optimism amongst staff and students
about the installations of the system on the campuses.
Buried greywater tank(containing pump) and filter
Quality of greywater
Interestingly, the impact of greywater on landscape in the short
term (less than a year) has been shown to be generally beneficial
to edible and non-edible plant growth.
“In most rural areas without municipal supply and far from
surface water, this quality of greywater has also been extensively
used for vegetable gardens. Short term (less than one year)
irrigation with bath and laundry greywater has proven to be
generally beneficial to edible and non-edible plant growth.
The impact of long term irrigation is still under investigation.
The same greywater system for toilet flushing may also be used
for irrigation.”
Greywater sieve
Retrofitted toilet (municipal flush via
handle and greywater flush via wall
bell switch)
Posters in the bathroom
The system collects its greywater from 13 hand basins and conveys
it to a 200 litre tank. Just before entering the greywater, there are
two 2 mm sieves that collect any solid materials which find their
way from the hand basins.
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Dr Ilemobade tells us the universities have further water saving
systems in place. They also have a rainwater harvesting system for
toilet flushing in the same building where the greywater systems
are. In one of the buildings, a UJ Student Town residence,
the rainwater harvesting system is the back-up supply for the
greywater tank. In the second building, the School of Civil and
Environmental Engineering at WITS University, the rainwater
harvesting system is separate from the greywater system.
By using similar systems such as the one the universities have put
into effect in their projects, we could all be doing the “royal flush”
(by water saving standards) before leaving the “throne room” and
save a lot of water.