Rain Water Harvesting
There’s a lot more to rainwater harvesting than buying a water tank, connecting it to your gutters and sticking a hose on the bottom of your tank. Yes, it can be as simple as that but it depends on what you want to achieve. For those who only want to water a small garden then fittings to the gutter, a water tank, a hose connecter at the bottom of the tank, overflow to your stormwater pipe and a hose is about all you need as long as your garden isn’t higher than the tanks water level.
(If you just want to know how to install your own water tank, just scroll down to the bottom of this page)
On the other end of the scale, there are those who want to water their larger gardens and lawns, wash their cars as well as use the tank water to flush the toilets, wash the clothes in the washing machine and top up the pool or water feature.
Not only do they need a lot of water capacity in their tanks but they need a pump powerful enough to provide enough to all these outlets, particularly if more than one outlet is in use at the same time.
Take this a little further and have the system set up so it uses the water in the tank to do all these things but when the tank water gets below a certain level, a switch on the tank automatically switches the system over to mains water. The pump shown below right is a Davey pump fitted with a Rainbank unit, designed for switching between tank water and mains water automatically. having a water switch of this type can save you a lot of money by having your tank connected to your toilets and your washing machine, both of which use a lot of water in every houshold.
If you are wanting to achieve this set up, our shop staff can provide you with all the information you need to avoid any pitfalls.
If you are going with the simple tank set up as described at the start, many people do it themselves but if you are wishing to claim a government rebate then you will need to have it fitted by a licensed Plumber or have a licensed plumber certify your work. If you are going to use your tanks to connect to your home (to the toilet or washing machine) you will need a licensed Plumber to do the work.
If you are wondering why we have not mentioned anything about using tank water for drinking water, it’s because that’s outside the scope of this website but it can be done and our shop staff can give you all the options and pricing.
GETTING THE WATER FROM YOUR ROOF INTO YOUR TANK(S)
Not all downpipes are connected together before they go into the stormwater. Downpipes can come off many different parts off your roof and go underground without connecting up with any other downpipes. This presents a difficulty when you have one tank or all your tanks are in the same location.
THERE ARE A NUMBER OF WAYS OF GETTING ALL YOUR WATER TO THE ONE LOCATION:
Connecting some of your downpipes together if practical, having the pipes directed under or around your house and up into your tank, which is called a wet system or using a stormwater pit at a low point on your property with your stormwater outlets all leading into it, with a sump pump and float switch to pump the water to your tank when the rain starts to fill the pit.
As you can see there are ways and means, some simple and some more complex but if you want some help when buying your tank, pump and fittings our shop staff can provide you with the advice you need.
You don’t necessarily have to catch rainwater from every part of your roof if you don’t need that much water to fill your tanks. Trying to use every part of the roof could make the project far more difficult than it needs to be so consider just taking the rainwater off those parts of the roof that can easily be collected and worry about collecting from the other areas if you are not getting enough water for your needs.
Our rainwater tank suppliers have some handy information on their websites that will provide you with further information on collecting rain water.
CALCULATING THE RUN OFF FROM YOUR ROOF AREA.
Most people install their rainwater tank and hope for the best but if you would like to know how many litres of water will go into your tank for every mm of rain you get then the formula is fairly straight forward. 1 square meter of roof area = 1 litre of water for every 1mm of rain.
For example if you calculate a total catchment roof area of 150 Sq meters and you get 12mm of rain, you will get an inflow into your tank of approximately 1,800 litres of water.
It’s surprising how quickly a tank fills up.
RAINWATER HARVESTING ACCESSORIES
There are many products available to help you to catch and save water efficiently. They help you to keep your water free of impurities and diseases, keep the mosquitoes out, gauge the water level, filter the incoming water and more.
The diagram below from Rain Harvesting graphically displays numerous rainwater harvesting accessories. Click on the link to the Rain Harvesting website Right for information on all their rain harvesting products.
- Check ROOF SURFACES for suitability for collecting quality rainwater
- Install GUTTER MESH (such as Blue Mountain Mesh) to prevent leaves and debris from blocking gutters.
- Fit GUTTER OUTLETS from the underside of the gutter to prevent obstruction of water flow.
- Fit Leaf Eater or Leaf Beater RAIN HEADS to downpipes to stop gutters blocking. Rain heads deflect leaves and debris & keep mosquitoes out of pipes that hold water (“wet” systems).
- Install WATER DIVERTER/S to prevent the first flush of most contaminated rainwater from entering the tank.
- Ensure the TANK SCREEN is installed at tank entry point to filter water and keep mosquitoes and pests out.
- Choose a WATER TANK. Consider annual rainfall, roof catchment area and water usage when determining its size.
- Attach INSECT PROOF SCREENS or FLAP VALVES to the end of all pipes to the tank screen (for ‘wet’ systems) and to TANK OVERFLOW OUTLETS to keep mosquitoes and pests out and ensure tank is vented properly.
- Ignore 9 as it is not allowable under current water restrictions
- a PUMP SYSTEM (if required) to distribute water for use inside or outside the home.
- RAINWATER FILTER. Fit a purpose designed rainwater filter after the pump to help reduce residual sediment, colour and odour.
- WATER LEVEL MONITOR. Install a level indicator to help monitor your water usage. Wireless systems are most convenient and display a reading inside the home.
HOW TO INSTALL YOUR OWN RAINWATER TANK.
See videos in the Rainwater Harvesting section.