Susan Davis

Last Monday, I had the pleasure of hearing about diarrhea research while munching on some pizza at Emory University’s School of Public Health. Dr. Stephen Luby, introduced as “the most famous diarrhea researcher” was talking about new approaches needed for addressing the world water crisis. In summary he said that we need to think beyond water quality, water, sanitation and hygiene (WASH) interventions as preventing diarrhea, and point of use water treatment. [For my non-technical friends, you might have “point of use” treatment at home – e.g., a Brita water pitcher or the PUR filter on your tap. Broadly, it’s something you do to your water in your house to make it safe to drink. That can include boiling it, putting something in it, or filtering it. “Point of use” is used to distinguish from centralized water treatment (at the water utility), which is what we generally have in the United States.]

For this blog I wanted to share the information he presented on point of use (also known as household water treatment), because he said something rather striking: “Point of use [water treatment] has failed to transform community health.”  Them’s fightin’ words in the water and sanitation world.

Proponents of point of use water treatment often say that building water systems for communities doesn’t seem to working very well, is expensive and difficult to maintain, and takes a long time to reach all the people who need it. Point of use lends itself to locally led or private sector initiatives and has potential to reach lots of people for less money than infrastructure initiatives.  Others say that focusing on point of use doesn’t deal with making water access more convenient, which is critical to achieve benefits not limited to health. Re-purchases of water treatment products or filters are often low, and the children who suffer the most are least able to afford the water treatment products or devices. My opinion is somewhere in between. Both methods could be improved, and both have a place in the world, perhaps in ways that complement each other. The debate, I believe, has more to do with scrambling for scarce resources than what’s best for the customer (aka beneficiary).

Dr. Luby highlighted results from several evaluations. I’ve attempted to capture those below. I found the links to the studies myself, so apologies to Dr. Luby if they are not the exact studies he cited.

In 2008, there was a study of Procter & Gamble’s PUR water treatment product (it is a powder that somewhat magically makes even muddy water safe to drink). P&G marketed it nationally in Guatemala. An evaluation in rural communities 6 months later showed only 5% of households were confirmed users, and they weren’t using very much (4 sachets per week). Proctor & Gamble stopped the national marketing.

In a 2008 study of the Chulli water purifier in Bangladesh, only 21% households reported regular use in the first set of interviews. [This was the first time I’d heard of the Chulli: it uses a combination of a sand filter and heat from a stove to kill microbes in the water. See the study for diagrams and photos.] Dr. Luby and team revisited the households 3 weeks later without representatives of the organization that had distributed the device and only 4% of the households reported use. (This shows the commonly seen “courtesy bias” – deep down none of us wants to hurt people’s feelings.) Poor durability, inconvenience, high cost, and post-treatment contamination limited the usefulness of the purifier.

A study of SODIS in rural Bolivia (where soda bottles and sunlight are used to treat water) showed that diarrhea rates were similar to controls, and only 32% of households were observed using SODIS.

The Safe Water System (SWS) program consists of water treatment at the point of use with a locally produced, diluted bleach solution, safe water storage, and behavior change techniques such as social marketing. The SWS program has been operating in Zambia since 1998.  A 2004 evaluation showed only 13% of households had residual chlorine (a way to prove that people are using the product), and the use of CLORIN did not affect the prevalence of diarrhea among children under the age of 5. The SWS program in Malawi began in 2002. During an evaluation in 2005, only 7% of the households reported using the product.

An evaluation of ceramic filters in Cambodia in 2006 showed 31% of households using filters at follow-up. About 2% of the filters broke per month. While the study says results are “promising,” these kinds of filters have challenges. Because they are fragile and awkwardly shaped, you can’t move them very far. This means they tend to be local industries, which means quality control is difficult.  Quality control is necessary to build a pot that is microbiologically effective.

A broad survey of the frequency of household water treatment across results from 2006 – 2009 in 67 countries by Rosa & Clasen showed that almost 30% of the people were drinking treated water (keeping in mind that self-reporting is usually overestimated).  Boiling is the most frequent method (21% of the people treating their water). However, boiling is expensive and is often problematic (deforestation is often caused by people who need fuel and burning wood or coal indoors causes respiratory and other problems).

Dr. Luby closed his talk by highlighting a quote from a Dr. Jeffrey Sachs talk in December 2011: “Social marketing is always a bad idea.” People are less likely to buy something after being given it for free.  Possible alternative solutions, said Dr. Luby, could include small water systems, which might be more affordable than large networks, and networked water supplies with shared responsibilities on repairs.

I’d love to hear your thoughts.  Does point of use water treatment have a role in solving the global water crisis?

And a postscript [March 3, 2012], I just re-read a poster presentation from the UNC Water & Health Conference in October 2011: “A Systematic Review of the Evidence for the Sustainability of Household Water Treatment Interventions,” by William E. Oswald and Karen Levy (Center for Global Safe Water, Emory University). They looked at 20 studies of various types of household water treatment (biosand filters, boiling, ceramic filters, ultra-filtration, flocculant-disinfectant, chlorination, SODIS) and extracted information on 7 sustainability criteria.

Oswald & Levy concluded that “We still lack quality evidence of a sustained, long-term change in practices as a result of HWT [household water treatment] interventions.”  They recommended further studies using sustainability criteria to identify which technologies are best suited to different conditions and users. The researchers also thought that “standard approaches and indicators, particularly for confirming usage, should be developed for the comparable evaluation of HWT implementation.”