Rain Water Harvesting in Water Tanks

“Water is the driving force of all nature”  - Leonardo Da Vinci

Rain Water Harvesting is quite simply the collection of rain water for use elsewhere. One of the common forms of rain water harvesting is to collect the water from the roof of a building into a storage water tank. The Kwa-Zulu natal North Coast is blessed with an abundant average annual rainfall of 1000mm – 1200mm. If you harvest this into a storage tank, you will get 1000 to 1200 litres per square meter. With a 200square metre roof, that’s an estimated 200,000 litres of harvested water per annum.

In a recent garden makeover, the owner setup a DIY rainwater harvesting system with a 2500lt storage tank and a pressure pump. The water is used in this instance as irrigation water for their garden. However, harvested rainwater can have a multitude of additional uses. It can be used as is for washing cars, high pressure cleaning of rooves and outside equipment, or filtered and plumbed to be used indoors for washing machines & dishwashers, flushing toilets, and even bathing and showering. If the water is sufficiently filtered it can also be used for drinking.

 Harvesting this free resource has several benefits:

  • As source water it is naturally chemical free with little chance for contamination other than the roof it falls on

  • Use of the harvested water alleviates the use of dam water storage thereby alleviating the stress on this infrastructure

  •   It also places less stress on the storm water draining system, reducing the risk of overload and thus also reducing the damage from flood water.

  •   Harvested rain water alleviates the stress on our water resources, particularly in time of drought

  • It reduces soil erosion – less water running into the garden means less soil erosion

  •   Naturally, free water falling from the sky means a reduced water bill every month. The cost savings benefit of 200,000 free water per annum is significant

  • For industrial water use such as factories these costs savings would be even more significant  

Considerations when undertaking a DIY Rain Water Harvesting project:

  • Consider your catchment area eg a roof – to capture the most rainwater possible, the gutters should be diverted to the collection point. The more gutters that are diverted, the more rain water you will collect

  •  It is wise to get the roof pressure cleaned before you capture your first rainfall, and to keep it clean from the elements of nature such as leaves, bird droppings and general debris

  •   You will need a small initial investment to get your DIY setup going, however, the significant cost savings in the long run will mitigate this cost

  •   Consider the size of the tank you will need for your particular use. If you are only going to be watering the lawn with this water, then a smaller tank of 1000-2000 litres should suffice, bearing in mind that rain doesn’t fall consistently throughout the year. If you have plans to filter the water for inside use, you should consider a couple of larger tanks for example 2 x 2500 litre tanks.

  •   Placement is also important. Water storage tanks are big and bulk and could detract form your beautiful garden setting if not placed well. Consider  fencing them off behind a trellis which you can then cover with a creeping plant. Courtyards are also well-concealed placement areas for storage tanks. If space is an issue, then consider underground storage tanks which will not inhibit the use of your lawn area. Tanks should also be placed either level with the ground or uphill of the house if you are going to use the tank without a water pump, to ensure the best flow.

In the below video, Water Pro Trading business owner Bruce Wacher talks more about Rain Water Harvesting into a water tank:

Feeling up to the task? If it sounds too daunting for you - feel free to give the experts a call. Click here for more information and contact details.

 Happy Rain Water Harvesting!