Posted by: Saving Water SA (Cape Town, South Africa) – partnered with Water Rhapsody conservation systems – 08 November 2010
Only a minute share of water in our planet (2.5%) is potable, and most is locked up as ice while only one per cent is available in lakes, rivers and underground water tables for human consumption.
In South Africa our average rainfall is only about half that of the global average – 450mm per year against the world average of 860mm per year. South Africa is a water stressed country yet little emphasis is placed on rainwater harvesting as a solution. Instead, we look erringly at energy expensive and non-sustainable fixes such as desalination.
By harvesting rainwater from our roofs, rather than using municipal water, we reduce stress on our estuaries and there is less extraction from our rivers.
Collecting or harvesting rainwater for garden irrigation may seem the obvious way to go, but during the rain season when irrigation is not necessary, an overflowing tank simply defeats the purpose of productive rainwater harvesting.
It makes far more sense to use harvested rainwater in the home, including garden. Every time you open a tap, flush the loo, or use the washing machine, or any other use of water, you first and foremost use the water harvested from your roof. This removes the romantic notion of filling a water tank and not knowing what to do with the water, or trying to fill a water tank with harvested rainwater that is full already!
A rainwater tank will fill quickly during rainfall, e.g. a metal roof will produce 1000 litres of harvested rainwater for every 100 sq. metres of roof area with 11mm of rainfall. For a tiled roof you need 16mm to produce the same yield.
An important factor to note when storing rainwater is prevention of mosquito infestation and using a UV stabilised storage area. Rainwater tanks are mostly UV stabilised but do nothing to keep out those pesky mosquitoes. This can only be achieved effectively by installing correctly specified filters at source.
Rain Runners (by Water Rhapsody) perform this important function and are installed at each downpipe. These are also self-cleaning and therefore require no maintenance.
Another interesting point to note is that with the Water Rhapsody system the rainwater tank does not need to be close to the downpipe or house. Pipe work from the gutter to the tank is concealed underground, so there is no longer a need to have an unsightly tank outside the lounge window.
Rainwater systems augment municipal supply meaning that should the rainwater run out the system will seamlessly change over to municipal supply, and as an added bonus you get up to 2-days of emergency supply at all times, so you’ll never run out of water, even if the municipal supply is interrupted.