HEALTH AND SANITATION
25
Do septic tanks work?
South African plumbers have an opportunity to help set
world standards; tell us about your experience with the
humble septic tank.
By Mike Muller
The United Nations wants everyone to have safely
managed water supplies and sanitation by 2030.
That’s going to create a lot of work for everyone in
the water sector. But, before that happens, we need
to know just what “safely managed” means and
how do we measure it?
With water supply, it is relatively easy: Does water come
out of the taps reliably and is the water safe to drink?
In South Africa, we already know the answer to the first
question (it has been getting less reliable every year). We
used to know the answer to the second question, until
Minister Mokonyane stopped publishing the Blue Drop
report because it was too embarrassing.
Sanitation is more difficult. We can estimate how many
blocked sewers spill muck and germs into the roads
and how many treatment plants are working (if only
the Minister would publish the Green Drop reports!).
But there are plenty of people who do not have access
to sewerage. That is why the UN’s Joint Monitoring
Programme is asking questions about septic tanks. Do
they work? And are they safe?
This is already a problem in developed countries. In
Ireland, there were near riots when, in compliance with
EU rules, the authorities started surveying the state of
septic tanks in rural areas — and charging people to be
inspected. The surveys found that many septic tanks were
unsafe, usually because their soakaways were inadequate.
The danger is that poorly treated waste could flow onto the
surface, spreading germs onto people’s shoes and hands
and then into their mouths and food.
www.plumbingafrica.co.za
So, it is of concern that some companies that sell
plastic septic tank units provide detailed installation
instructions on how to bury the tanks but give no
guidance on what is needed for a good drain field. This
can be a real problem on small sites where there isn’t
enough room. Drain fields work in two ways: either
the liquid evaporates from the soil, or it soaks into the
ground. Either way, it needs enough space to do that
— the old city regulations used to prohibit septic tanks
on stands less than 2 000m 2 .
Now, septic tanks can be a real boon in p laces where
there are no sewers, as in many of the extensive
settlements in the former homelands. People there want
— and often can afford — to have a flush toilet, but
they won’t get one if they wait for their municipality to
install sewerage. So, we should be planning for this and
providing guidance on how to build proper systems.
The other question is, where is the water for flushing
going to come from? Many rural water supplies have
been designed to provide 50 litres of water per person
daily. As people in Cape Town are discovering, that is not
enough if you are going to flush every time you use the
toilet. In Cape Town, because of the crisis, household
water use is being strictly monitored but in our rural
settlements, that is the exception — not the rule.
Mike Muller
Mike Muller is a visiting
adjunct professor at the
Wits University School
of Governance and a
former Commissioner
of the National Planning
Commission and Director
General of Water Affairs.
So perhaps the real problem with septic tanks is that
they are using a lot of water, which means, very often,
that there is not enough to go around. That’s one more
thing for the new Minister to think about! What advice
would you give him? PA
July 2018 Volume 24 I Number 5