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For me your comments raise additional key questions. Understanding the total yield potential of the boreholes and recommended total pumping time will be critical in the first instance before any technical solution is sought. For me this would indicate whether or not an additional borehole is in fact indicated from this perspective, rather than a pumping technology perspective.

Then assuming the yield capacity is adequate, the next thing to consider is the bigger picture of the long-term sustainability of the overall system. Introducing additional costly components in my view only adds to the potential critical failure items on the system. If we choose to add batteries, have we determined the overall system efficiency and will be end up also adding additional panels in order to store enough energy and/or be able to pump and store at the same time. My fear is that the life-cycle of batteries are significantly shorter than that of the pump and the panels and when they fail they will simply not be replaced as deep-cycle batteries are really expensive.

At the end of the day, taking a wider view and looking at the overall lifecycle costs, the capability of the operators to maintain the systems, etc, I would suggest that investing in additional boreholes or alternative supplies may well be the more prudent decision (I was tempted to add “in the medium term” but in fact I think even in the short term).

I cannot see from the email stream what exactly the details of the project are, but assuming that this is a WaterAid funded project, I would suggest that we undertake a yield assessment, followed by a rough series of scenario costings of the different options (not only capital but a 10 year life cycle costing) which will in my view provide a solid basis from which to choose a route forward.