The study of eight arsenic-safe water options showed that overall, only 62% of households with access to a safe water option (N = 1268) actually use it (Inauen et al., 2013a). The study also revealed great discrepancies between user rates for the different water options. The most used options were piped water, followed by community arsenic-removal filters, well-sharing, deep tubewells, dug wells, pond sand filters and rainwater harvesting systems (Fig. 9.7). Clearly, if more people would use the options which are accessible to them, the public health burden would be reduced. Psychological factors determined from the RANAS model of behaviour change (risk, attitudes, norms, abilities, self-regulation) (Mosler, 2012) are an aid to better understanding the reasons why some options are preferred over others (Inauen et al., 2013a). A piped water supply was most popular in terms of taste and temperature preferences, followed by strong social norms (i.e. that many relatives and friends are in favour of using arsenic-safe water sources, and that they are also using them), high confidence in their ability to obtain as much arsenic-safe water as needed (i.e., self-efficacy, Bandura, 1997) and high commitment (i.e. a personal desire, Inauen et al., 2013c) to consuming piped water. Interestingly, deep tubewells also enjoy a high degree of acceptance, despite only moderate user rates. This may be due to the fact that collecting water from deep tubewells has been reported as time-consuming, which may have led to lower commitment (Inauen et al., 2013c). Households with access to neighbours’ tubewells only reported below average social norms for using them and low commitment, perhaps also because users are dependent on their neighbours' consent. At the other end of the spectrum, dug wells were perceived as time-consuming and were associated with taste and odour issues. The next step was to analyse the survey data to forecast the most promising promotion campaigns. Self-efficacy and the descriptive norm (i.e. how many other people use arsenic-safe water options, Cialdini, 2003), emerged as the most important factors to explain the use of arsenic-safe tubewells (Inauen et al., 2013b). Further important factors were instrumental attitudes (i.e. the perception of water collection as time-consuming and hard work) and the injunctive norm (i.e. what one thinks that others think should be done, Schultz et al., 2007). This was applicable to all arsenic-safe water options included in the study. Summarising, these studies indicated that more committed persons, who perceive safe water collection as “normal” and have higher confidence in their abilities to collect safe water, find safe water collection less time-consuming and less of an effort, and those who feel they have more approval from others when they collect arsenic-safe water are more likely to use arsenic-safe water options. Given their general acceptance, deep tubewells were chosen for promotional campaigns to overcome the issues of distance and lack of commitment. To increase commitment, the most promising factor of deep tubewell use, they developed reminders, implementation intentions (simple plans of when, where and how to obtain arsenic-free water, Gollwitzer, 1999) and public commitment (sometimes termed “pledging”, Fig. 8.8), and combined them with risk information (Fig. 9.8, Inauen et al., 2013c, Gollwitzer, 1999). The results of a randomised controlled trial revealed that evidence-based behaviour change techniques increased the behaviour change effect by 50% compared to simple information provision (Inauen et al., 2013c). But also less “spontaneously” accepted and used arsenic-safe water options can be promoted by targeting any of the psychological factors identified above. For well-sharing, for example, the commitment-enhancing behaviour change techniques described above increased the number of users by up to 66% (Inauen and Mosler, 2013).
The analyses of water from shallow and deep tubewells in the tested area of Sreenagar, Munshiganj, identified three types of groundwater currently used for drinking:
- Shallow water from 20 to 100 m: dark-grey sediments with high As concentrations (100–1000 mg/L), intermediate to high Fe (2–11 mg/L), intermediate Mn (0.2–1 mg/L) and relatively low electrical conductivity (EC) (400–900 mS/cm), dominated by Ca–Mg–HCO3.
- Water from 140 to 180 m: light-grey sediments with low As (<10 mg/L), intermediate Mn (0.2–1 mg/L), intermediate Fe (1–5 mg/L) and intermediate EC (1200–1800 mS/cm), dominated by Ca–Mg–HCO3-Na-Cl.
- Deep water from 190 to 240 m: brown sediments with low As (<10 mg/L), high Mn (2–5 mg/L), low Fe (<3 mg/L) and high EC (2000–3000 mS/cm), dominated by Ca–Mg–Na–Cl with high Ca and Cl concentrations.
Drillers have traditionally used the transition from grey to brown sediments as an indicator of the depth from which safe drinking water can be obtained. However, in most of the tubewells in the study area below 190 m, the Mn concentrations exceed the WHO limit of 0.4 mg Mn/L (WHO, 2011) by a factor of 2–5, and the water tastes noticeably saline. Based on these findings of this small survey of deep tubewells, a depth range of 150–180 m with light grey sediments is recommended for the construction of new wells. The finding of an “intermediate depth” at which water which is safe not only with regard to arsenic but also with regard to salinity and manganese is echoed by Hossain et al. (2012), who found good quality groundwater at 120 m in Chandpur, one of the most highly arsenic-affected areas in the country. Groundwater from this depth contained moderate levels of iron (2–4 mg/L), but iron in the region is also common in shallow groundwater (~10 mg/L), and locals are accustomed to the metallic taste. The surveys in Monoharganj have shown that the concentrations of arsenic, manganese and salinity as a function of depth are locally highly variable and that the best depth for water extraction should be determined in each community in which a larger number of deep tubewells are planned. Finding a depth with acceptable water can be difficult in some locations, and newly installed deep tubewells often deliver water that is too saline or that contains high manganese concentrations. Methods are being developed that allow drillers to test the water quality during the drilling process and to install well screens at the optimal depth. More generally, high salinity in deep tubewells is also common in parts of the coastal zone as well as in the Sylhet basin, and manganese concentrations frequently exceed both the government limit of 0.1 mg/L and the WHO health-based value (WHO, 2011) in central and northern Bangladesh (UNICEF/BBS, 2011). Owners have reported damaged pumps that apparently corroded more quickly due to high salinity.
These studies have shown that there is considerable agreement between the wishes of the institutional stakeholders and rural householders with respect to the preferred mitigation options, namely, piped water and deep tubewells. Further, there is agreement between institutional stakeholders and householders about cost. However, the institutional stakeholders were of the opinion that a distance of 0–250 m (or 10–30 min) per trip was acceptable, whereas householders perceived water collection as time-consuming and hard work. These studies also showed that there would be significant potential for reducing the number of people exposed to arsenic if householders used the safe-water options available to them. They also showed that information alone would not be enough to change people’s habits. Evidence-based behaviour change techniques to increase commitment would be required. With respect to deep tubewells in the Sreenagar district, it was found that, although free of arsenic, water taken at depth can be saline and contain unacceptably high manganese concentrations. Water taken from intermediate depths (140–180 m) fulfilled the quality requirements. Further, pumping tests showed that the deeper aquifer was to a large extent separated from the upper aquifer, so that the abstraction of small amounts of water for drinking using hand pumps can be deemed safe as long as wells are periodically tested.
The institutional stakeholders identified a lack of capacity at the level of the locally elected sub-district councils (upazila parishad). They also mentioned a lack of accountability and coordination between organisations. These appear to be good starting points to improve mitigation outcomes. The role of awareness creation appears to the institutional stakeholders to be an important factor in reducing exposure to arsenic, while the results of the behavioural change study indicate that the introduction of simple behaviour change techniques to “empower” the local population to make use of existing facilities, particularly well-sharing and deep tubewells, could make a significant difference to the number of people at risk. With respect to deep tubewells, it must be remembered that groundwater quality is spatially highly variable and that safe zones within the deep (or intermediate) aquifer are site-specific. It is therefore recommended that in areas where deep tubewells are to be installed, safe depth zones should be identified by surveying existing deep tubewells and, if possible, by the installing of a small number of monitoring wells, which could also serve as sources of drinking water. Maps can be very useful.
NOTE: Article from the Geogenic Contamination Handbook