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.
How do they work?
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.
Kits are available to suit metal, poly/plastic, concrete and fibreglass tanks
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.