Notes to broadcasters
- For many rural dwellers it is more and more difficult to get access to water. This situation will likely become more serious in many areas with rising temperatures due to climate change.
- This script discusses some of the factors that can be taken into consideration when planning a catchment system that collects water from both sloped and flat rooftops. This information will be of special interest to women who often walk a long way to fetch water for the household.
If you are a woman and you walk a long way to fetch water, today we have some good news for you. We’re going to talk about a way to collect water with less effort – by catching it on your roof!
That’s right. You might be surprised to discover how much water you can collect from the roof. You can collect water for washing, for cleaning, and for watering your garden. It’s important to understand, however, that the amount of water you can collect from a roof is likely not enough to water staple crops such as grains and beans.
If you want to build a rainwater collection system, you are going to need a pipe or gutter to carry the water from the roof, and a storage container.
I’m going to start by talking about the gutter. You can make a gutter from tin, or from a large, split piece of bamboo, or from a piece of wood. Remember that your gutters will have to be big enough to carry large amounts of water during a heavy rainfall.
Once you have your gutters, attach them firmly to the roof or the outside wall of the building. The gutters should slope slightly down towards the storage tank. You don’t want any pools of water to form in the gutters.Musical break
The size of the container will depend on how much water you need and on the costs of construction. Large amounts of water can be stored in tanks or cisterns that vary in capacity from one cubic metre (which holds 1000 litres) to hundreds of cubic metres. A typical maximum size for a home system is 20 or 30 cubic metres.
If you’re thinking about collecting water from your rooftop, you might be wondering how clean that water will be. Something to keep in mind is that any dirt on your roof will affect the quality of the water.
The materials that the roof is made of will also affect water quality. For example, thatch may contaminate the water or make the water a different colour. Or chemicals from the roof can get into the water. Because of this, you will not be able to use the water for drinking or cooking. If you want to use your water for drinking or cooking, you will have to invest in a filtering system, or other kinds of water treatment.Musical break
But what if you have a flat roof?
If you have a flat roof, you may think that you can’t catch much rain.
But any roof can be improved to catch more water.
Here’s a simple way to collect water from a flat roof.
What you need to do is attach a vertical panel to your roof.
When I say “panel,” I mean that you could use a piece of wood, a piece of metal, or a piece of plastic. Any material will work as long as it is solid.
Once you have the panel, attach it securely to the top of the roof, on the side of the house that faces the wind. For example, if, when you face your house, the wind usually comes from your right side, then attach the panel to the right side of your roof, between the front and back of the house. If the wind usually comes from the back of your house as you face it, then attach the panel to the back of your roof, between the left and right side of your house.
When you attach the panel at a right angle to the roof, the top of the panel will be higher than the flat part of the roof. Rainwater will then blow into the panel, and slide down it directly into the gutter.
If you have light winds, use a tall panel, about two metres high.
If there are strong winds in your area, use a shorter panel. Or, use a panel that can be easily removed in case of heavy winds. If the panel is too tall, strong winds might blow it down.Musical break
Thank you for listening.
- This script is adapted from script 54.7, which was written by Vijay Cuddeford, managing editor at Farm Radio International.
- Reviewed by: Neil Noble, Practical Answers Technical Adviser, Practical Action.