These prevent mosquitoes, pests and vermin from entering the pipe systems and the water tank.

Mosquitoes spread diseases at an alarming rate and breed in water. Ensure multiple screen rain heads are installed at the entry point of gutter downpipes. Fit insect proof flap valves or screens to the end of the pipe system at the entry to the rainwater tank, and to the overflow from the tank. The tank should be vented so as to allow a flow of air/oxygen over the surface of the water thus improving its aerobic content. This also prevents a vacuum when large quantities of water are quickly drawn off from the tank. Flap valves should have double seals, be self-cleaning, and have a flap that cannot be over rotated and left open.