Water quality before and after a campaign of cleaning and disinfecting shallow wells: a study conducted during and after ﬂ oods in Khyber Pakistan

This study reports on a water quality assessment of the Water, Sanitation and Hygiene program implemented by the Swiss Agency for Development and Cooperation in the districts of Charsadda and Nowshera in Khyber Pakhtunkhwa, Pakistan, in the aftermath of the severe ﬂ ood of 2010. During emergency operations, over 4,500 shallow wells were cleaned using the standard protocol suggested by the World Health Organization. Bacteriological analysis and chemical-physical parameters such as temperature, conductivity, turbidity and pH were tested before and after cleaning. Four to ﬁ ve years after the emergency operation, in 2014 – 15, a set of 105 representative wells was analyzed again, considering the same parameters and looking for additional contaminants (pesticides, arsenic and ﬂ uoride). The post- ﬂ ood well-cleaning campaign was effective in the immediate reduction of fecal contamination of water (from 85% to 20% as measured 7 – 30 days after cleaning); however in the following months/years the rate of fecal contamination rose again (up to 62% of all measured domestic wells, n ¼ 105). Along with laboratory analysis data, this study investigated the source of contamination of shallow wells and identi ﬁ ed human practices in several cases. This information was useful for the design of future SDC interventions in the WASH sector.


INTRODUCTION Background and context
Wells are an important source of drinking water in many countries today. A large proportion of the world population is drinking water from wells of varying depth, water volume and water quality. Most of these wells are hand dug, having a diameter just large enough for the diggers, and they may or may not be lined to protect them from surface water contamination. Many have no wellhead structure to prevent contaminants from entering them. This makes them very susceptible to pollution from agricultural activities as well as fecal contamination from improperly sited latrines. The health risk related to drinking water from private wells has been identified (Fewtrell & Bartram ; Wolf et al. ), not only in developing countries, but around the world including the USA, through the evaluation of risks for children consuming drinking water from private wells (Rogan & Brady ). However, the advantage of private wells lies in the fact that they are inexpensive to dig and can be accessed using simple manual methods such as a rope and bucket, eliminating the need for more complicated and expensive drilling and pumping equipment (Rowles ).
As stated by Bain et al. (), 'access to an improved source provides a measure of sanitary protection but does not ensure water is free of fecal contamination nor is it consistent between source types or settings'. The authors of this study agree with these conclusions, also supported In 2010 the entire northwest of Pakistan was badly hit by floods that affected around 20 million people nationwide.
In the province of Khyber Pakhtunkhwa (KPK), this flooding contaminated thousands of wells and presented a public health hazard that outlasted the immediate threat of the flood itself. According to Relief International (), 98% of the water and sanitation facilities in the area were severely damaged or unusable due to heavy rain or water flow in the two districts of Charsadda and Nowshera. The availability of drinking water became a big concern, as most water sources, including the groundwater, were contaminated and the wells were unusable.
Emergency relief efforts were provided during the floods and later measures were taken to assist the affected populations in getting through the winter. In August 2010, the Humanitarian Aid Unit of the Swiss Agency for Development and Cooperation (SDC-HA) started various reconstruction projects in the domains of public infrastructure, drinking water and disaster risk reduction (DRR).

Well cleaning and well rehabilitation
The immediate relief operations focused on 'well cleaning' using the standard protocol suggested by WHO and Traditional wells in the region are particularly vulnerable to contamination from surface water, they are characterized by brick casing, shallow water (sometimes less than 5 m, never more than 10 m) no apron and short distance to sanitation facilities and domestic animals. There were no consistent data on water quality before the flooding.

Objectives of the study
This study focuses both on the short-and long-term water quality effects of the SDC Water, Sanitation and Hygiene project in the district of Charsadda in KPK, which involved more than 100,000 beneficiaries using more than 6,000 domestic wells. This project included well cleaning and well-improvement measures as well as water treatment and hygiene awareness activities. Domestic wells were rehabilitated at the household level, and the technical staff of service providers was trained in the management and maintenance of water supply facilities (where available). The two components of the program are illustrated in Figure 1.

Ethical aspects
With the aim to build research partnerships in the most constructive, balanced and results-oriented manner, and recognizing that transboundary and intercultural research in partnership is challenging, the entire project has been conducted from the beginning (design) to the end of the hydrogeology of the project area in order to determine the different paths of contamination. Further, the study aimed to confirm or complement the overall information on beneficiaries in the project area, with a special focus on social information pertaining to the acceptance of awareness campaigns, effective change of habits, or the proper use of household water treatment and safe storage (HWTS).

Sanitary inspection of wells
The sanitary inspection of wells was performed according to World Health Organization procedures (1997), using risk-of-contamination scoring ranking from 1-11. This includes the evaluation of following diagnostic parameters: (1) Is there a latrine within 10 m of the well? (2)

Fecal contamination and sanitary inspection during and soon after emergency: 2010-13
Soon after the flood of 2010, over 4,500 wells were rehabilitated/cleaned, with over half analyzed before (n ¼ 2,348) and soon after cleaning (n ¼ 2,380). Figure 2 indicates the degree of contamination of wells with fecal coliforms and/ or E. coli while Table 1 indicates the distribution of wells

Analytical work 4-5 years after emergency (2014-15)
Several years after the flood event, 105 wells were retested for bacteriological contamination and chemical and physical properties.

Data on bacteriological analysis
The distribution of fecal contamination is illustrated in Figure 3. Bacteriological analysis showed a significant presence of bacteria indicating fecal contamination, with roughly 65% of the samples being contaminated. A significant difference was found between wells rehabilitated by the addition of manual pumps as compared to those without manual pumps (see Table 2 below). Wells with manual pumps, implemented in the village of Dildar, presented nearly no fecal contamination. Hand-pump rehabilitation represents a significant improvement of the well, preventing it from external contamination, mainly caused by dirty buckets and/or ropes.

Data on chemical and physical analysis
Physico-chemical analysis of the samples did not show any major public health concerns with respect to the reference values suggested by WHO with the exception of EC, turbidity, SO 4 , Cl, F and the values for biocides commonly used in the surrounding agricultural area. While major ions do not represent a significant problem (Table 3), widespread contamination with biocides in the water table (insecticides in particular) has been shown (Table S1, see Supplementary Information, available with the online version of this paper).
In Table 3, there are a few specific points to note.
Regarding physical parameters, two samples presented some slightly increased turbidity (10 and 18 NTU); ten samples presented higher electrical conductivity (salinity); one sample presented increased total dissolved solids.
However, these exceedances do not pose a major threat to human health. With regard to chemical parameters, 11 samples presented slightly higher concentrations of sulfates, one sample presented a slightly higher concentration of chloride, and one sample presented a slightly higher concentration of fluoride, a water parameter raising health concern.
It is interesting to note that the values for nitrates and  ammonia were relatively low, considering that latrines often do not fulfill the requirements for the minimum safe distance to wells. Further, fluoride and arsenic seem not to be a major health concern in this area of Pakistan. Finally, regarding biocides, a widespread contamination with the chemical residues of agricultural biocides can be detected in the study area. This finding represents a preliminary result that should be confirmed with a new collection of samples to be analyzed by a reference laboratory, including an analysis for heavy metals (fertilizers). local authorities should be informed and advised in order to take proper preventive actions to address contamination of groundwater with biocides, providing that this study finding is confirmed by a reference laboratory.

Contamination reduction
The well-cleaning campaign promoted by SDC soon after the floods was effective in reducing fecal contamination in the drinking water; contaminated wells dropped from 85%

CONCLUSIONS
The results of this study should be useful for any organization implementing well-cleaning/rehabilitation campaigns after floods. The well-cleaning campaign promoted by SDC for gaining access to mud-covered wells and reducing fecal contamination in drinking water proved to be effective.
The subsequent well rehabilitation program, accompanied by a soft component of hygiene promotion, was necessary for human health. Well-cleaning actions should always be conducted during emergency operations in the wake of floods in locations where domestic wells represent the main source of drinking water. However, this action does not guarantee water safety in the long term. The present study demonstrates that contamination with fecal matter, as measured several years after the emergency phase, appears again in domestic wells. The main source of contamination seems to be related to human practices, such as the use of dirty buckets/ropes, animals defecating close to open wells, and unprotected wells collecting surface runoffs. The reason of this return to the initial situation might be due to a lack of behavioral change within the population.
Given that a change in sanitary infrastructure, mainly pit latrines, may take time or not occur at all, to improve bacteriological quality of domestic wells, better protection of the wellhead is the recommended action. This means changing the way in which water is taken from the well by installing hand pumps and closing the wellhead to avoid runoffs entering into the wells. Hygiene promotion and behavioral change appear to be effective instruments for preventing this type of contamination. Fecal contamination is a more locally restricted problem, occurring at the domestic well level. Regarding chemical contamination, while major ions represent rather a minor problem, the widespread contamination of the aquifer with biocides (insecticides in particular) presents a major health concern.