Stop the Rot: History of the Rapid Corrosion Problem in Zambia and Potential Next Steps

Report by Javan Nkhosi and Kerstin Danert

A collation of observations by professionals, technical audit reports, evaluations, consultancy reports and academic research has found evidence of rapid corrosion in at least 22 countries in sub-Saharan Africa. The phenomenon appears to be widespread, and, in many countries, is ongoing. Unfortunately, neither the histories of this phenomenon nor the geographic extent of it have been well documented.

This report, published in July 2023, presents the history and geographic extent of the rapid handpump corrosion phenomenon in Zambia. It describes the fragmented and seemingly forgotten solutions that have taken place since the 1980s. The report charts when and where the phenomenon became evident in the country, the measures taken (or not), and what was learned (or not), and proposes next steps for the Zambian government and its cooperating partners to tackle this pervasive problem.

Rapid handpump corrosion occurs when aggressive groundwater reacts with galvanised iron (GI) riser pipes and rods of a handpump, and the India Mark II in particular. The materials corrode, with the pumped water becoming bitter in taste, with an unpleasant smell and a rusty colour. This not only renders the water unfit for drinking from a user perspective but also considerably reduces the pump lifespan. In Zambia, the main cause of rapid handpump corrosion is contact between groundwater with a pH of less than 6.5 and GI pipes and rods. However, salinity is also a problem in some parts of the country and can result in rapid corrosion too.

The use of alternative materials to GI, particularly stainless steel (SS) riser pipes and rods and uPVC rider pipes fitted with stainless steel connectors, can prevent rapid handpump corrosion. While rapid handpump corrosion was documented in West Africa in the late 1980’s, and actions to prevent it have been taken in some places, the phenomenon still occurs in over 20 countries in sub-Saharan Africa. Zambia, with an estimated 22,000 handpumps in use, serving 32% of the population with their main drinking water supply, is among these countries.

In Zambia, while the geographical extent of aggressive water is not fully understood by water sector professionals, it has been documented and explained with respect to soils. A Soil Survey by the Mount Makulu Research Station from 1990 presents the situation clearly, with extreme soil acidity in the north, and soil acidity in the central parts of the country. Further, in Zambia the traditional Chitemene – ‘slash and burn’ – method of cultivation in the high rainfall region has been used since time immemorial to neutralise low pH in soils in order to cultivate crops. Leaching from these highly acidic soils affects the pH of the groundwater.

The problem of rapid corrosion in handpumps in Zambia has been known for more than 30 years (Pitcher, 2001) and is well documented, including in the following:

• The Central Province Rural Water Supply Project (CPRWSP) (1985 – 1996) – which installed 564 handpumps with stainless steel riser pipes rather than using GI to prevent rapid corrosion.
• The North-Western Province Rural Water Supply and Sanitation Project (2004 – 2009) – over 350 handpumps were installed with stainless steel riser pipes, also in response to the same issue.
• In Luapula Province under the Japan International Cooperation Agency (JICA)-supported Groundwater Development Project (2007 – 2010), some Afridev handpumps with uPVC riser pipes were installed. The project rehabilitated existing, corroded handpumps which the community had previously abandoned. Replacing the GI pipes with uPVC stopped the iron problem, indicating that in these boreholes, using iron pipes had been the cause of corrosion.Iron removal plants were also installed on some boreholes.

However, while solutions were implemented at scale in the aforementioned projects in Central and North-Western Provinces, as well as the study in Luapula, the use of GI riser pipes and rods still continued in subsequent projects in the same areas, e.g.:

• Central Province Rural Water Supply and Sanitation Project – CPRWSSP (2000 – 2007), which drilled or rehabilitated over 3,400 boreholes and installed GI riser pipes. Rehabilitated handpumps may have in fact even replaced some of the stainless steel riser pipe handpumps that were installed under the CPRWSP outlined above.
• Both GI and stainless steel components were availed through the spare parts shops supported by the Sustainable Operation and Maintenance Project – SOMAP 2 (2007 – 2010).
• The Zambia Social InvestmentFund(ZAMSIF)projectinstalled India Mark II pumps with GI pipes and rods in Luapula province. They were subsequently rehabilitated by a JICA project (2000 to 2005).

This study has not able to uncover the reasons for this unfortunate turn of events, but it is worth noting that:

• There was a change in the ministry responsible for drilling works. The period 1985 – 1996 saw borehole drilling under the Department of Water Affairs, while the Department of Infrastructure and Support Services under the Ministry of Local Government and Housing took on this role after it had been created in 1995.
• National Guidelines for Sustainable Operation and Maintenance of Handpumps in Rural Areas (MLGH, 2007b) includes neither aggressive water as a criterion for handpump selection nor the use of stainless steel riser pipes, and so the use of GI pipes in aggressive water as the cause of the ensuing rapid corrosion was in effect further supported.

In the last ten years, further initiatives to understand and address the problem have been undertaken, including:

• Under the SOMAP 2 project (2012 – 2013), the JICA-supported programme carried out pipe replacement of GI at 20 sites in four provinces (Luapula, Copperbelt, Central and the North Western) whereby GI pipes were removed, the boreholes flushed and then installed with uPVC pipes. The replaced handpumps performed well without the water turning rusty, and the communities continued to draw water from them, whereas previously they had been abandoned.
• UNICEF also carried out pipe replacement in Mansa and Milenge districts of Luapula Province.In the study, India Mark II handpumps GI pipes at 45 sites were replaced with uPVC riser pipes. After the pipe replacement of GI riser pipes, the community used the handpumps that had previously been abandoned, with unsafe water sources being used instead. The pipe replacement study was successful, with the water users returning to previously abandoned boreholes which had clear, rust-free water.
• There is some evidence of other projects and organisations starting to use either stainless steel riser pipes, or uPVC riser pipes with stainless steel connectors in their projects, but documentation is limited.

While stainless steel riser pipes have been used effectively, there are also some outstanding technical issues – particularly in relation to the removal of narrower diameter riser pipes, which require suitable tools that are not in the standard India Mark II toolkit. Further, the use of uPVC pipes has also been found to be problematic, as they need to be cut on removal and cannot easily be re-threaded. However, at least one NGO in Zambia has been using an alternative, comprising uPVC with stainless steel couplers which is available on the Zambian market. A further complication is that some parts of Zambia appear to exhibit naturally occurring iron. Tests are available to determine whether iron is naturally occurring or a result of corrosion, but there is no comprehensive map to indicate areas at risk of high levels of geogenic iron.

Despite all of the efforts to date, and notwithstanding the widespread nature of rapid handpump corrosion of GI riser pipes and pump rods, the problem still persists in 2023. There is no government policy position on the problem or solutions, nor is there any standardisation of which handpumps to use in areas affected by aggressive groundwater.

The report provides a number of recommendations for consideration by the Government of the Republic of Zambia (GRZ) in order to mitigate, reduce and ultimately eliminate rapid corrosion of GI riser pipes and pump rods as follows:

1. revise the National Water Policy to include aggressive water in community boreholes;
2. restrict types of handpumps to certain regions, with due consideration of suitable technologies for water depth;
3. enact a law and a statutory instrument on aggressive groundwater in community boreholes;
4. incentivise the private sector for provision of quality, corrosion-resistant riser pipes and rods;
5. standardise handpumps used in Zambia.

The study also recommends further research on:

▪ replacement of GI riser pipes,
▪ the phenomenon of naturally occurring iron in ground and surface water and
▪ saline water in Western Province.

You can download the full report here.