Chapter 1 - The importance of chemical toxicants in Water, Sanitation, and Hygiene (WASH) provision

1.2 Chemical toxicants are overlooked in conventional WASH programming

The challenge of chemical toxicants to water and health has yet to be appreciated by the WASH sector. This is illustrated, for example, by chemical toxicants forming the subject matter of only tiny fractions of WASH journal articles and conference presentations (Figure 1.1)[5]. To nearly all environmental scientists, engineers, and toxicologists working outside the WASH sector this is truly a bizarre state-of-affairs.

Figure 1.1 Evidence of absence: major WASH journals and conferences have featured very few articles or presentations on chemicals[5]. 

How is it that chemical pollutants have been left out of the WASH development agenda so far? To answer this question, let’s briefly review the origins of what can be called the “conventional WASH” paradigm. 

Conventional WASH was first codified in the Millennium Development Goals and later updated (slightly) for the SDGs. During the Millennium Development Goals period from 1990-2015, the WHO/UNICEF Joint Monitoring Programme (JMP)[23] reported on the proportions of developing countries’ populations using “an improved drinking water source”[24]. An “improved” drinking water source includes things like public taps or standpipes, tubewells and boreholes, and piped water inside a household’s yard or dwelling[24]. Water quality or safety was not a factor under the “improved” rubric. It wasn’t until 2017 (!) that “safely managed” was added as a criterium for the JMP under the SDGs[25]. The definition of “safely managed” is that drinking water is obtained “from an improved water source which is located on premises, available when needed and free from faecal and priority chemical contamination”[25]. The priority chemical contaminants are fluoride and arsenic. Under the new rubric, no heavy metals or organic chemicals are considered “priority.” 

Thus, under conventional WASH there are no metrics for chemical safety of water (apart from fluoride and arsenic). Most large development programs are driven by efforts to achieve prespecified metrics – measurable quantitative increases in X (e.g., number of household water taps), or decreases in Y (e.g., number of cases of diarrhea), etc. With no metrics established regarding chemicals, it’s not surprising that large WASH organizations have not pursued interventions (i.e., treatment technologies) that can remove them.*

Biochar water treatment, on the other hand, did not emerge from the conventional WASH paradigm. I first developed the idea of water treatment using biochar (a form of charcoal) in collaboration with rural agricultural communities in the Thailand-Burma border region in late 2006. (I recount the origin story of biochar water treatment in section 1.4.) Using charcoal in water filters is an ancient practice still familiar in many subsistence and agrarian communities. The question arose whether it would work to remove modern chemical pollutants such as pesticides. This question became the subject of my research as an independent scientist, then as a PhD student, then as a member of university engineering faculty, and now as the topic of this book. In other words, biochar water treatment wasn’t invented to fulfill a metric or “check a box” prespecified by a large government or non-government development agency (or more likely, imposed by the funders of those agencies), but rather to address a local concern and meet a local need at the grassroots level with available materials. When it comes to chemical pollution, “poor” communities in the developing world are often much more advanced at WASH innovation than the highly-paid and well-credentialed “experts”!

* The prevailing conventional WASH approach to mitigating exposure to arsenic and fluoride in drinking water is source switching, for example by identifying tubewells in Bangladesh with red or green paint according to whether they were above (red) or below (green) the national standard (50 mg/L), and promoting rainwater harvesting in areas with fluoride in excess of the WHO Guideline Value of 1.5 mg/L.


[Next up: 1.3 Moving towards transformational WASH]