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Sarah,

You've got some excellent answers here from Vinny and Lawrence. As Vinny said, your most strategic starting point is to remove and examine the pump components. Heavily corroded (rusted) riser pipes and rods are indicative of aggressive groundwater and may be the source of your high iron. I will point out though that many older (30+ years) boreholes may have iron casing, which could also be an iron source (though there is no easy fix for this problem). Otherwise, the aquifer may indeed be the source of naturally-occurring iron, which is unlikely to damage pumps but can have a significant effect on users perceptions and preferences for using the borehole.

The testing process that Vinny described above is a very good one and a relatively simple way to help determine the source of iron. The idea is that if iron is emanating from corroding components, you will see iron concentrations reduce along with excessive pumping as water that has been sitting in the borehole (and receiving iron as a corrosion byproduct) is replaced with water from the aquifer.

You also might want to look into this: best practices for drilling would include water quality testing (including iron), so you should determine if such information is available from the original implementer, the well driller, or possibly the government if there is a system for such records. Unfortunately though, this data is not always reliable, as I have seen from experience in Uganda. However, it is something worth looking into.

Additionally, if your organization is currently or will be implementing more borehole water points, it would be prudent to ensure that testing take place at the time of drilling and documented within a drilling report that is retained and (hopefully) integrated in to government records. This will help you in choosing the proper pump components and thus preventing unnecessary financial burdens on whoever is responsible for O&M of the borehole in the future.

Good luck!

Jake