Fine sediment, which can contain harmful bacteria and heavy metals, eventually builds up in the
bottom of rainwater tanks. It is important to maintain the tank to prevent this sediment being drawn
out through the outtake pipe for use.
The Rain Harvesting Tank Vacuum System automatically vacuums the sediment off the bottom of the tank
in the area of the outtake pipe every time the tank overflows. The systems are supplied in kit form
and fit all types of tanks, including metal, plastic, concrete and fibreglass.
A Tank Vacuum System helps prevent sediment, which can build up on the bottom of the tank, being
drawn through the outtake point for use.
When water flows into the tank and the tank fills the excess water escapes via the tank overflow
outlet, but with this patented system the water enters the interior siphon pipe “D” at the bottom at
point “E”.
As the excess water rushes up “D” it draws the sediment off the bottom of the tank like a vacuum
cleaner. The water that is siphoned to waste is from the Anaerobic Zone which is the worst quality
water. With a standard overflow outlet, water from the top of the tank (the best quality water) goes
to waste.
An anti-siphon device in the elbow at the top of the tank "C" prevents the exterior overflow pipe
"F" from siphoning water out of the tank. “F” is best fitted with a Tun Dish (a Leaf Catcha ® rain
head is ideal) under the tank overflow outlet. The outlet can be fitted with an insect proof Flap
Valve that also prevents siphoning.
Normally tanks have an outtake point at “A” which draws the water from the Anaerobic Zone which is
the poorest quality water in the tank. Where possible fit another outtake point 250-300mm above the
bottom of the tank "B" so that better quality water is drawn for use from the Aerobic Zone.
