Rain harvesters

TechnologyWater Supply

Information in Footsteps has helped people build ferro-cement tanks for rainwater. However, many people need to know how they can avoid mosquitoes breeding in these tanks. Here are some practical steps I have developed to make a dome shaped cover…

  • Measure the diameter of the top of the tank and add 3–4cm.
  • Cut a piece of string to exactly half this length.
  • Mark a centre point on level ground and move the string around this point to mark a circle on the ground.
  • Dig away some of the soil and press down firmly to form a gentle hollow.
  • Cover the soil with paper or sacking.
  • Lay 1/4 inch (6mm) metal wire across the circle in both directions about 6–10cm apart and tie together.
  • Also, if available, lay chicken wire or mesh on top.
  • Cover with a firm cement and sand mortar (one part cement to three parts sand) so the cover is 2–3cm thick.
  • Cover with damp sacking and leave to harden for several days.

If a small opening is required in the lid, first place a basin or tin between the wires before applying the mortar. Make a cover using mosquito netting or a tight fitting basin.

You can also use this method to make a flat cover – simply make the cover on flat ground. However, a dome shaped cover is stronger.

Dickson Tenywa, The Rain Harvesters Technicians, PO Box 15131, Kibuye, Uganda.