Catch All the Rain that Falls on your Roof

Backgrounder

Did you know that your roof can catch a lot of water for you?  The first few rains of the season may be all your area will get for the whole year.  But if you can catch all the rain that falls on your roof you will have water for your gardens and fields, your livestock, and your household later in the season.

For years, many people in Botswana and some in Zimbabwe have been trapping water from rooftops.  Your roof can collect a generous amount of water, even during light showers.  It does not matter if your roof is grass thatched, or made of sisal‑cement, clay tiles, or metal.  The only difference is that water collected from thatch is often discoloured and is usually contaminated.  So do not use water collected from a grass‑thatched roof for drinking.  Use it only for watering plants.  Tile or metal roofs give the cleanest water.

It is easy to collect water from your roof.  Place a container below the roof in which to catch the rainwater.  Now you will need a gutter to direct the water to the container.

People in Botswana have found simple ways of making gutters from metal sheets, bamboo rods or wood.  Here is how you can make effective rainwater gutters.

If you are using a metal sheet, cut the sheet into long, thin rectangles.  Fold the rectangular sheet of metal along its length to form a gutter.  If you are using bamboo, split the bamboo rods into two halves and remove the partitions.  Without the partitions, bamboo rods make good channels for water.  If you are using a piece of wood, hollow it out along its length.  Or attach two planks of wood together lengthways in a “V” shape.  Water will flow along this groove.  Apply tar or wax to the joint so that water will not be lost through the joint.

Use wire or rope to tie the gutters to the eaves or edges of your roof.  Place the gutters on a slope so that the water will flow from one gutter to the next.  Again, use wax or tar at the joints between the gutters to reduce water loss.  Use a few poles to support the gutters.  You will need stronger poles or more poles especially when heavy rain falls.

Rain that falls on the roof will collect in the gutters.  Then it will flow from the gutters into the container you have placed under the roof.  Use a few poles to support the gutters.

You may install a pipe to channel the water from the lowest point on the gutter into a storage container.  As you may have been doing already, you can use a plastic tub, an old bath tub, or a large, well‑cleaned petroleum drum to store the water.

If algae grows in the storage container, do not worry.  Algae will not harm your plants.  Cover your rainwater collector to prevent evaporation and contamination, and to discourage mosquitoes from breeding there.

Rather than storing the water in containers for future use, you may direct rainwater trapped from the roof to a pit around which plants are growing.  Put some small stones, compost or other mulch in the pit.  The stones will let the rainwater soak slowly into the soil.  The mulch will act as a sponge to absorb all the water and supply it to the plants around the pit.

By collecting rainwater from your roof, you can make the most of any rain that falls.