Wednesday, April 16, 2008

Water 102: Rainwater Harvesting or Collection

Every year, thousands of gallons of clean, pure rainwater are lost to floods in some of the most impoverished countries around the globe, countries that are struggling with water availability issues. Here a woman from Hue, Vietnam struggles through a flooded street (source: 1ieve). Why not catch the water and use it, rather than lose it??

I am a HUGE supporter of rainwater collection. In most cases, rainwater is some of the most effectively clean water that you can possibly get. I say most because if the air surrounding the clouds or the air between you and the clouds is polluted (with dust, sulphates, nitrates or other chemicals), the pollutants mix with the rain and contaminate it. Generally highly industrialized areas or desert areas with high dust contents are problem areas. And even in these cases, if it rains continuously in high volumes, then the first couple of rains flush the area out and the next sets become cleaner. And even in these cases, the water is safe for gardening, washing clothes and bathing. It does need to be boiled, disinfected, and/or filtered for cooking and drinking.

Islands and areas with high rainfall, are the perfect places to implement rainwater harvesting. Many of the equatorial regions, which also have high poverty rates would benefit greatly from rainwater harvesting. While the rain is seasonal, collecting and storing water during that period can get one through some of the dryest summers.

The concept itself is simple - find a way to collect the rainwater funnel it into a storage area. So it has three parts:
-a catchment area (a roof, trees, the earth)
-a storage area (pots, tanks)
-piping that takes you from catchment to storage area. It doesn't have to be a pipe, its just a system to take the water from catchment to storage (reeds, pipes, gutters)

The key to a good rainwater collection system is a clean, covered storage area...this is MOST critical. If the collection area is dirty, wait 15-20 mins for the rain to flush off the area, then start collecting after.

By far, one of the best threads on rainwater harvesting in the developing world is here on changemakers. They talk about everything from how to check the quality of your water to how to install the system, etc.

In many cities and towns, water can be collected from roofs using a gutter system that funnels the water into a barrel. In rural areas, this can be a bit difficult with thatched or hay roofs. When large leaves are used it is a bit easier. Still, some of the best and simplest water harvesting I have seen have been in tribal communities across Asia and Africa (haven't been to Latin America yet, though I'm sure they are experts too), who use the trees surrounding their living areas to funnel water into pots.

A woman in rural India collects water using a length of cloth hung between two trees, a weight and a pot. (source:

On Jeju island in Korea, traditional women matt together brush and reeds and let water drip into the pot. Usually for the first rain, the water was allowed to flush the brush, and was used for agriculture only. But after that, the brush acts as a funnel and a filter, and the resulting water is used for everything. (source: James Lim)

A rainwater harvesting system designed by students at Clemson University, South Carolina (source: Clemson U)

Regardless of whether you are in a developed or developing country, I would highly recommend installing a rainwater collection system (you can design your own using the gutter system on your house).

Other resources:
An introduction to Rainwater Harvesting, one of the best rainwater harvesting websites
Is rainwater clean enough to drink?
Who's up for drinking rain?
Drinking rainwater

1 comment:

Water filters said...

Well look at that how much water got wasted on roads after such a rainfall if their is still shortage of water in the city than government should take some serious steps for having water harvesting system get installed on state level and providing citizen some affordable means to collect water.