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Hi George,

You don't say how they collect water from the reservoir is it a piped outlet to taps? Is it a closed tank? Does it enter the tank via a pipe? What is the pressure head at the inlet to the tank.

There are various devices that can be used on a pipe that is flowing full to dose chlorine solution such as water-powered pumps (e.g. Dosatron) and venturi suction systems. Unlike the drip system, these only work when the water is flowing and the dose can be made to be proportional to the flow.

There are other devices that may also be suitable. Look at the publication Chlorinating Small Water Supplies – A review of gravity-powered and water-powered chlorinators that you can find at https://wedc-knowledge.lboro.ac.uk/details.html?id=16614

If it is a surface water source it is likely to have a variable chlorine demand even if it is pre-settled, depending on recent rainfall runoff that will affect the turbidity and organic content. If this is the case then having a set dose (even id proportional to the flow) will be problematic since the water quality (and hence the chlorine demand) can vary from day to day.

First consider if it necessary to treat all the water they use. If people can be trained and motivated, it may be more cost effective to dose the chlorine solution at household level and to dose just the water used for drinking and food preparation. If you do this it also deals with potential problems of post-treatment pollution of chlorinated water at or after it is collected from public water points. However, users still need to store it hygienically in the home and to allow 30 minutes contact time for the disinfection to take place.

In haste,

Brian

Brian Skinner WEDC