HEALTH AND SANITATION
59
“Additional benefits of using the Rainwatch in a rainwater
harvesting system include that it reduces the need for
separate leaf catchers and first flush devices, and it
reduces the maintenance load or replacement frequency of
downstream filtration equipment. It can be easily cleaned,
and the filter itself is washable and reusable, meaning that
maintenance costs are very low.”
It’s made from polycarbonate and acrylonitrile butadiene
styrene (ABS) plastic combined with a filtration membrane
designed to filter contaminants as small as 50 micron. It
slows and cleans the water over a large filtration surface,
allowing significant flow rates. This means that the filter
can capture water without overflow wastage, even in heavy
rainfall. Most rainwater catchment systems use large run-
off areas to collect rainwater, which then goes through a
centrifugal pump. This pump breaks up the contaminants
into fine particles, making them difficult to remove even with
fine post-tank filters.
This Australian product helps to improve the quality and
health benefits of rainwater. Doust says its development was
inspired after reading reports on the number of contaminants
present in rainwater tanks, even those with post-tank filters.
“The Rainwatch filter is the first patented filtration device
that cleans water and extracts sediment before it’s stored in
the tank. This both increases the quality of the rainwater and
reduces the hassle of cleaning the tank,” he says.
Behold the clarity of the rainwater.
“Traditional rainwater systems are pumping contaminated
water to the point of use because the particles are too small
for the filter to catch. However, because Rainwatch is a
gravity-feed pre-tank filter, it’s able to remove most airborne
contaminants and microscopic particles. When rainwater
is combined with a complete filtration system that includes
a Rainwatch, it makes it safer and more viable to drink,”
explains Doust.
“While the Rainwatch filter has the ability to remove most
airborne contaminants and microscopic particles, the
product is designed to be an addition to current rainwater
filtration and sterilisation systems rather than a replacement.
It allows water to be treated for human consumption, but
it is not designed to independently eliminate point of use
sterilisation for human consumption,” says Doust. “We
recommend it be used in conjunction with a UV filter close
to the point of use to ensure the healthiest consumption of
rainwater possible.”
Due to the extraction of contaminants before the storage of
rainwater, Rainwatch helps to significantly reduce sediment
build-up in rainwater tanks, extending the de-sludge
cleaning period from every two to three years to every five to
ten years. “This provides huge time and cost savings to tank
maintenance, which is the main cause of poor water quality.
It also reduces the need to empty the tank and waste the
precious rainwater in order to clean it,” says Doust.
The filter still needs to be cleaned every three to six months,
but the cloth can be replaced every three years depending
on the volume and frequency of rainfall and the level of
April 2020 Volume 26 I Number 02
The Rainwatch filter has been designed to work as a
component of all current rainwater catchment systems, with
a polynuclear aromatic hydrocarbon (PAH) removal efficiency
of 97%. PAHs are chemicals that can be released into the
air, water or soil from burning, industrial processes and the
use of some household products.
Rainwatch’s certificate of patent.
exposure to contaminants. The Rainwatch filter is designed
to increase the catchment efficiency of most current
rainwater systems, which is particularly important given that
South Africa – like Australia – continues to experience a
decrease in the availability of water.
“Water restrictions and environmental factors have
resulted in a scarcity of water resources, so even though
municipalities are struggling to supply high-quality water,
prices are continuing to rise. Rainwater tank installations
and maintenance services consequently represent a huge
opportunity for plumbers,” says Doust. PA
“Rainwater
tank
installations
and
maintenance
services
consequently
represent
a huge
opportunity
for plumbers.”
www.plumbingafrica.co.za