Revision history [back]

Dear Sarah,

I agree with Lawrence; iron originating from the corrosion of GI rods and pipes can also occur in dissolved form and not be immediately visible to the eye until subsequent oxidation. In other words, if you pump the water and it is initially clear but turns cloudy later, the source of the iron is not necessarily coming from the aquifer. It is possible that this dissolved iron originates from corrosion of pump materials. This observation is based on experience of the problem with IM2 handpumps and methods for diagnosing the origin of iron in Uganda.

The groundwater in the area where you are working may be considered to be non-corrosive, evidenced by nuetral pH values (around 7). This does not discount the possibility of corrosion. The quality of GI pump parts available on the market at the moment is so poor and loosely regulated (with many components verging on counterfeit) that corrosion can occur even if the pH of groundwater is neutral (non-aggressive). Again, this is based on experience of observing the quality of IM2 pump materials imported from India and China onto the open market in Uganda.

It may be that high iron IS coming from the aquifer. You will be able to diagnose the origin using the simple test set out in my previous response.

High iron in the aquifer will not in itself cause pumps to break down. Iron metabolising bacteria that derive their energy from oxidising dissolved iron may produce a slime that clogs up the pump pipes and cylinder, affecting pump performance. The evidence for this is discussed in a study by Fader (2012).

In summary:

1) Iron may be coming from corrosion of the GI pipes or from the aquifer.

2) You can use the test in my previous reply to diagnose the origin. Additionally you can open the borehole and pull the pipes out to look for evidence of corrosion.

3) If high iron is coming from the corrosion of GI pipes it can occur in dissolved (clear) form AND/OR in oxidised precipitate form.

4) The quality of many GI pipes is so poor these days that they even corrode and leak in non-aggressive groundwater conditions.

5) Bacteria that feed on dissolved iron (originating from the aquifer or from the corrosion of GI) may form a thick slime which could block up the pump cylinder.

6) High iron in itself will not damage the pump. Corrosion of sub-standard materials or clogging by iron metabolising of bacteria will.

7) The best way to find out what is breaking the pumps is to remove the down the hole components and take a look. Iron may not be related to the problem at all.

Cheers,

Vinny