We have developed a device that automatically mixes chlorine into water in the correct proportion, regardless of the flow rate of the water. Our device can be fitted to a rural community’s existing water source, such as the hand pump of a well, the tap of a rainwater harvesting cistern, or the faucet of a piped water system. It does not require electricity, has no moving parts to fail and uses only gravity to operate. As opposed to conventional water purifiers, a Zimba can handle thousands of litres per day and is therefore able to supply more people with their water needs. On top of this, there are no expensive cartridges to replace.


From the beginning of the project, durability was known to be a key feature required. Moving parts such as hinges and gears are known to be the first point of failure in most designs. So from the outset, we strived to design a product with no moving parts.

Gravity Powered

Electricity is expensive, unreliable or not available in many rural locations. Batteries too are not always available so we knew a design that didn’t require a circuit board would have a greater range of applications and wider appeal. Gravity and the force it exerts on water is all that is needed to power a Zimba.


The ratio of water to chlorine required for drinking water is so fine that it is measured in parts per million. This causes problems for most people working with chlorine. Zimba, however, does work within the sensitive parameters and does it consistently.

engineering for social change


  • No Electricity
  • gravity powered
  • No moving parts
  • Can handle high flow rates
  • Can handle low flow rates