Preparing Your Roof Catchment Area for Rainwater Harvesting

If you have a house or recently installed a new shed, then chances are you will want to tap into its rainwater harvesting potential. Connecting a rainwater tank at the end of downpipes from your roof is the ideal solution. This article will provide you with information to ensure your roof is adequately prepared and suitable for as a catchment area for harvesting rainwater.

Type of Roof Surface #

If you are going to use the water in the tank to water your garden, the quality of the water collected is not so much of an issue. Most roof surfaces are acceptable for this, even roofs made of asbestos. Unsealed asbestos is considered hazardous environmental contaminant, so you would need to ensure such is sealed with a non-lead sealant. If your rainwater is going to be consumed however, then additional safety measures will need to be taken.

Firstly, you need to determine whether the roof surface itself contains any potentially harmful chemicals or toxins. Toxic materials such as asbestos, uncoated lead flashing, or roofs painted with lead-based paint or primers need to be painted with a non-toxic sealant to prevent contamination. You also need to check whether there is any exposed treated wood on the roof surface. If present, this would also need to be sealed as the chemical preservatives used to treat wood are toxic and can leach into the water. Bitumen is another potential toxin that is commonly used on roofs as a waterproofing agent. If the roof surface has been treated with a bitumen product avoid using the harvested rainwater for drinking purposes.

Tall Trees and Overhanging Vegetation #

No matter what you are going to use the water for, it is best to keep leaves and other debris out of the rainwater tank. Fitting a leaf screen to the gutter system, installing a leaf-shedding rain-head or first-flush diverter will help prevent leaves from washing into the tank.

It is also best to trim back any vegetation or branches that overhang the roof, as these can serve as perching or roosting areas for birds. This will prevent more leaves, insects and droppings from falling on your roof than is necessary. For drinking water, you should install water filtration on your kitchen taps and where it will be consumed.

It is also wise to check whether any surrounding or overhanging vegetation is poisonous or not, as leaves from poisonous plants could add harmful toxins to your water source. If any poisonous plants occur nearby that pose a potential hazard, it is recommended that they are removed, or trimmed right back and their growth monitored regularly for encroachment.

Other Potential Contamination Hazards #

Other sources of potential contamination include:

• flues from heaters or furnaces
• overflow pipes from geysers, solar hot water tanks and air conditioners.
• pollutants from nearby chemical spraying and industries such as manufacturing plants, spray painters, quarries and the like.

In the first two cases, you should avoid using that section of the roof for harvesting rainwater. In the latter case, if spraying has recently occurred it is recommended that you disconnect your water tank from your roof and wash it down.

You can maintain high water quality by screening your gutter, and using water tank accessories such as leaf eaters, water strainers and especially water diverters.

Gutter Pitch #

If there is not enough fall from the gutters to the downpipes, water can remain in your gutters providing conditions favourable for algal growth and mosquitos. You can prevent this by ensuring water effectively flows to your downpipe. If the water does not flow efficiently, adjust the pitch of the gutter accordingly.

When purchasing a Clark Tanks’ tank you are receiving a leading Australian brand with a high reputation in the country for reliability. Clark Tanks would be happy to answer any further questions you might have about setting up your rainwater tank for harvesting high quality water.