Many Southlanders use rainwater for home use and around their garden either in conjunction with water supplied by the Invercargill City Council or as their only supply.

House and building roofs are primarily used as a means of collecting water the water for household water use. The following is a guide on how to minimise contamination of rainwater.

Roofs and spouting

The roof and spouting should be cleaned by scrubbing every few months. It is important to disconnect the line feeding the tank prior to cleaning so that the cleaning products and run-off does not enter the water tank. After a long dry spell the first rain should be diverted to be used as wastewater by disconnecting the downpipe from the inlet to the tank as this may contain bird droppings, dust and other contaminants from the roof. The first rainwater should also be diverted after painting, treating or cleaning the roof.


The tank should be emptied and all debris and sludge removed (either by draining through the tank scouring valve or by suction cleaning) and the internal surfaces of the tank thoroughly cleaned (by scrubbing) on an annual basis.

Underground pipes

Underground pipes feeding the water tank should have a cleaning eye fitted and the water trapped in the pipes should be drained every few months.

Contamination from unwanted material into your water supply can be minimised by cutting back overhanging tree branches; keeping roof and gutters clean; using lead-free roof, paint, nails and soldering; installing a self-cleaning rainwater strainer; ensuring the tank lid is tight fitting; screening tank overflow; placement of outlet 150mm above the tank floor; ensuring that the cleaning eye on pipe is located in a hole filled with gravel; adding a hose vacuum breaker; and not gowing vines/creepers on the sides of buiding or tank.