Rain Water Harvesting in 10 Steps

rooftop rain water harvesting

Rooftop rainwater harvesting systems can vary from a simple gutter to rain barrel to a more complex integrated system with above ground or underground water tanks of various sizes and configurations.  The rainwater harvesting steps below provide excellent advice.

1. Ensure that the roof surface is suitable for collecting quality rainwater

Colorbond® and Zincalume® steel sheets, well fired glazed tiles, concrete/cement tiles, clay tiles and composite tiles are popular choices for rainwater collection. If water is intended for drinking-: (a) contact the manufacturer to confirm whether the roofing material is suitable for potable water collection, and obtain a certificate of classification, (b) ensure all pipes and fittings used within the system are also approved, and (c) check local Council requirements.

2. Ensure roof gutters are installed to the appropriate standards and building codes with the regulation fall to the outlets

Gutters that pond water create a potential mosquito breeding habitat and can be an incubator for bacteria. Gutters must be installed with a fall of no less than 1:500 for eaves gutters (unless fixed to metal fascias), and 1:100 for box gutters.

3. Install a fire proof gutter mesh system to prevent leaves and debris from blocking gutters

Screening material MUST be fire proof and allow maximum sunlight into the roof gutter system. Screening material must NOT be too fine or create a shade house for spiders. [Fit gutter system in accordance with the International Plumbing Code and Australian Standards]

4. Fit rain heads to downpipes to divert leaves and debris

Rain heads direct leaves and larger debris out of the flow of the water. The type of rain head that is required depends on the type of system.  Multiple screen rain heads are best. “Wet” systems require rain heads to be fitted with screens that are mosquito proof (<1mm apertures). Rain heads that screen the larger material onto the ground are better than “junk basket” types.

5. Fit insect proof screens to all pipes that hold water (“wet” systems) and all pipes and openings to/from your 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 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.

6. Fit appropriately sized first flush water diverter/s

This is a critical factor in achieving good quality water. First Flush water diverters prevent the first, most contaminated rainwater from entering the tank.

The recommended volume to be diverted is based on an assessment of (1) roof area, and (2) a pollution factor (between 0.5L to 2L of water per m2 of roof area). The volume, type of downpipe system, and site characteristics will determine the type of water diverter required. Water diverters with a variable volume chamber are better than “fixed volume” diverters, because they can be customized to the specific requirements of each site. For best results with a “wet” system, the volume held in the pipes should be added to the roof diversion quantity.

Select an appropriate water tank, tank ‘top-up’ and pump system.

7. Choose a water tank.

Consider annual rainfall, roof catchment area and water usage when determining its size.

8. Utilise a dual water supply system (if required)

To automatically ‘top-up’ the tank with the mains water when tank water levels fall to a designated minimum level.

9. Select a pump system (if required)

To distribute water for use inside or outside the home.

10. Ensure the system is maintained

This is one of the most important factors in ensuring good quality water. All components, including gutters, rain heads, water diverters and water tanks, should be serviced regularly. Consideration should be given to registering your rain harvesting system with the local Council.

Source: RainHarvesting (Australia) via RainHarvest (USA)

Rainwater harvesting is one of the only ways to obtain ‘free water’ and can be accomplished relatively easily.  The water tank is the heart of a rainwater system for rain water storage and should be chosen carefully (quality, size and type).  In South Africa we recommend rain water tanks and other products made by JoJo Tanks; click on the links below to see the various JoJo Tanks products available.

JoJo Tanks South Africa offer a wide range of plastic water tanks and chemical tanks to suit every household, business or agricultural need, including silo tanks and silo tank stands.  See JoJo Tanks VERTICAL TANKS, HORIZONTAL TANKS (transporter tanks), STEEL TANK STANDS and OTHER JOJO PRODUCTS. Also see JoJo Tanks’ NEW 6000 LITRE UNDERGROUND TANKS. Also see our FAQ and WATER TANK PRICES.

JoJo’s superior polyethylene plastic water tanks and steel water tank stands make JoJo Tanks the leaders in plastic water tank technology and the quality, affordability and guarantee on these water tanks make JoJo products the best choice in South Africa.  JoJo’s water tanks and chemical tanks come standard with a number of features that are often lacking on cheaper/inferior plastic tanks made by other companies in South Africa.

We are authorised JoJo Tanks dealers in South Africa and dispatch orders directly from JoJo Tank depots to save on transport costs. Full range of JoJo Tanks products and JoJo water tanks for sale.  CONTACT US for a quote on the right JoJo water tank or other JoJo product for you.  Special discounts are available on multiple orders of chemical tanks and water tanks and to our commercial and government customers.


(15000 litre and 20000 litre JoJo vertical water tanks also available on order)

Live in the USA and need rainwater harvesting equipment?  Click HERE!

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