Scotland Island has a number of water-related issues. The island is not connected to Sydney Water or the city sewerage system. This means that we have unique conditions which entail some careful management and knowledge of local conditions.

The average house has 136,000 litres of rainwater per annum deposited on its roof. Even in a dry year, it will be over 100,000 litres. Collecting this water for your water tank is one of the challenges. Here are some tips to help.

Collecting water

It is important to maintain your rainwater tank and components so they work effectively and reduce the risk of contamination. Preventing problems before they arise will save you time, money and water. A few simple measures will keep your collection system clean, drinking water pure and sweet.


  • Clean water starts with a clean roof, so sweep your roof before any predicted rain.
  • Warning: Roofs are too dangerous and slippery for children.


  • Keep gutters clean of dirt and leaf litter and plug up any leaks.
  • The best gutters for collecting clean water are 150mm half-round supported from underneath. Overstraps make cleaning difficult.


  • Keep downpipe system simple with a minimal number of bends.
  • Create a simple way of deflecting water away from catchment tanks to avoid collecting dirty water if roof and gutters have not been cleaned.

First flush devices

  • Use first flush devices to prevent the first rains from flowing into the tank after a dry period. This will reduce the amount of dust, bird droppings and other debris that have accumulated on the roof.
  • An alternative to a first flush device is to manually disconnect the tank inlet so that the first run-off is not collected, or to divert the water away from the collecting tank.


  • Keep vegetation out of water supply with a simple filter at the base of the downpipe or at tank inlet. An effective system which fits into your downpipe with a larger grid to stop leaves, twigs, bark, etc and a fine mesh to block remainder. Some people use stockings as a filter.
  • Clean filters after the first good downpour has cleaned your roof and gutters.


  • Optimally, your tank should have at least a 40,000 litres capacity.
  • Have at least two tanks – a collection/settlement tank and a storage/header tan.k
  • If possible, use a gravity supply instead of pump pressure supply as water usage will reduce, particularly in showers etc.
  • Get inside your empty tanks and clean them thoroughly if they are dirty.


  • Check gutters regularly to prevent ponding of water where mosquitoes can breed.
  • To prevent tanks from becoming breeding sites, add a teaspoon (5ml) of domestic kerosene; however do not use kerosene in Aquaplate or some types of plastic tanks. Check with the manufacturer of your tank.
  • Use light, flexible screening (available from some garden shops) to cover collecting tanks and other water containers where mosquitoes can breed.


  • Once the Spotted Gum bark starts to fall towards the end of the year, rain water tanks can very quickly become tainted with organic matter.
  • Too much organic matter in the tank can cause problems. As the water warms up in the hottest months, it creates the perfect growing conditions for unwanted life forms.
  • Be diligent in cleaning your roof and gutters at this time. If you have overhanging trees or do not collect water from your roof, wait until bark-shedding season is over.

Emergency Water Supply

  • The SIRA water supply lines can be used to fill your water tanks with non-potable Sydney Water that is piped from Church Point.
  • Bookings MUST be made prior to filling. Using the system without a valid booking is theft.
  • Please read about the Emergency Water system here.