The selection
of one of these
materials for a
rainwater storage
tank will largely
depend on local
availability, as well
as on cost, storage
requirements, site
accessibility
and/or engineering
specifications.
Concrete tanks
are durable and
strong. They
can be installed
above ground or
below ground in
various shapes
and forms.
Plastic tanks
are the most
common
material used
for residential
RWH systems
in South Africa.
Fibreglass
Fibreglass tanks are very versatile as they
can be installed above or below ground.
They are rigid and fairly lightweight and can
be easily repaired. Because their individual
strands are very fine and sharp, you should
be careful with parts that have been cut.
Polyethylene and polypropylene (plastic)
Plastic tanks are the most common material
used for residential rainwater harvesting
(RWH) systems in South Africa. This is
because they are lightweight, come in many
sizes and colours, and are affordable as a
solution. Polyethylene is flexible plastic and
polypropylene is a rigid plastic. Both can
be translucent or opaque. An opaque, solid
colour is better for reducing the chances of
algae growth.
UNDERGROUND TANKS
Most tanks are above ground; however, if
you do not want your tank to be visible or
to take up your precious backyard space,
you have the option of burying your water
tank underground. They are constructed
from a variety of materials: polyethylene,
steel, fibreglass or concrete.
www.plumbingafrica.co.za
29
HEALTH AND SANITATION
Plastic underground rainwater tanks are a type of rainwater tank that is
designed to be installed underground while still operating effectively. These
tanks are made from UV stabilised polyethylene (food grade) and are specifically
designed and manufactured for strength, with factors such as large ribs added
to the water tank walls. Modern polyethylene water storage tanks that are
designed to be installed underground can be positioned underneath driveways,
allowing a car to be driven over the top of the tank.
Concrete underground tanks tend to be more expensive to install than
polyethylene water tanks, as more excavation is required. Those tanks are also
at little risk of rusting, corroding, or damage from tree roots. Because concrete
tanks are stronger, they are ideal for placing under driveways, courtyards, sheds,
or other areas where they have to take heavy loads. Concrete underground
rainwater tanks are either precast or poured on site to client specifications. PA
In the next issue, we will look at the design and installation of rainwater storage tanks.
March 2019 Volume 25 I Number 1