Rainwater harvesting is the collection and storage of rainwater; in countries or regions that have low rainfall it’s a significant method of supplementing water supplies.
In many less developed societies rainwater is often the main source of drinking water,so rainwater collection is vital. Catchment structures dating back to 3000 BC have been found in India, and underground storage tanks have been discovered throughout the Mediterranean and Middle East.
Rainwater harvesting systems have the advantage of being easy to build from locally available material, and even in some cases you can find for free.
Roofs are obvious catchments and if they are going to be used it makes a lot of sense to clean them regularly. Dust, leaves and bird droppings aren’t a pleasant sight in a glass of water…
The rainwater can be collected in pots at the edge of the roof or ideally from down-pipes connected to gutters. When it first starts to rain, debris from the top of the roof or gutters is washed into the down-pipe, so it takes a while for clean water to filter through the system. A technique to remove this first flush of dirty water is by the use of down-pipe flaps. When it starts to rain, the flap is closed and the water is directed away from the storage tank onto the ground. Once clean water can be collected, the down pipe flap can be opened and the clean water is diverted into a storage tank. Fitting sieves to the top of the down pipe further decreases the risk of dirt getting into the water.
Rainwater Harvesting Techniques for Homes
The storage tanks have taps which are at least 10 cm above their base, so any dirt (which settles on the tank bottom) won’t be drawn off when the tap is opened. In this way the stored water should remain clean.
Consider that in top roof rain water harvesting, if roofs, gutters and down pipes are cleaned regularly, the water from rooftop systems frequently meets WHO drinking water standards. Going to extra measures to ensure it’s drinkability is also encouraged.
Rainwater harvesting techniques can be simple
Water from ground catchments is really only suitable for agricultural purposes but does have the advantage of collecting water from a large area. Small streams can be diverted into reservoirs and the water used to irrigate crops or feed livestock.
The disadvantages of rainwater harvesting are few, mainly the limited supply and uncertainty of rainfall. The advantages are many. The rainwater harvesting equipment is simple to obtain and build and doesn’t need any specialist skills or equipment to run. The construction materials are easily available and running costs are negligible. And as it is collected using existing structures, rainwater harvesting has few negative environmental impacts.