Quality of drinking-water at source and point-of-consumption--drinking cup as a high potential recontamination risk: a field study in Bolivia.

Diarrhea, often linked to intestinal pathogens in drinking water, remains common in many countries. In this interesting paper, investigators in Bolivia traced the extent of fecal contamination (as determined by Escherichia coli levels) in household water at various points from its source to the point of ingestion. Essentially pure at the source, the water was contaminated during transport to the home and further contaminated during home storage. Then, home water treatments (when used) typically purified the water, only to have it recontaminated with its transfer to drinking cups. Fecal contamination of drinking water continues due to household habits even when water is pure at the source.

Diarrheal disease, often transmitted through contaminated drinking water, accounts for more than a million deaths per year. In many parts of the world, extensive effort has led to the availability of pure water in communities.
Nonetheless, diarrhea remains common.
These Bolivian investigators cleverly looked at the contamination of drinking water in three geographically distinct rural and semi-urban communities. Contamination was tested at the water source (home wells, piped tap systems and delivery truck water), in the transport container or tap, in the home storage container, following home purification treatment (boiling or solar-powered disinfection) and in drinking cups.
In the three communities, the median contamination level (colony forming units of E. coli per 100ml) of source water was zero.
Contamination rose to 7 as it arrived in the home (transport barrel/bucket or tap) and to 15 in the home water storage container.
In the homes that purified water, contamination was effectively reduced to zero.
With some inter-house variation, contamination rose to 8 in drinking cups. People in only about half (53%) of households cleaned their transport and storage containers even weekly, and drinking cups were washed at least daily in only 48% of households.
Clearly, pure community-level water and even purified water in homes did not ensure water safety. Contamination through transport, storage and drinking containers was common.
Community-based interventions providing pure water must be accompanied by home-level implementation of container washing and, potentially, hand hygiene.
Another recent study showed that the use of hand sanitizers effectively reduced in-home levels of hand contamination with fecal pathogens, even more so than washing with soap and water {1}.
While hand sanitizers are not often feasibly affordable and available in water-constrained environments, they could be an added adjunct to hand hygiene when they are available.
Great efforts are in progress to provide good water sources in communities in the developing world.
This is laudable, but this Bolivian paper reminds us that our job is not complete until we ensure that water is still pure at the point of ingestion. We should extend educational efforts regarding the washing of household utensils and regular hand cleaning even as pure source water is provided.
Clinical practice is not changed by this study. Nonetheless, practitioners in areas where diarrhea is common despite the availability of pure source water should focus efforts on household hygiene.
Daily cleaning of water transport and water storage containers could be effective, and habits should be developed whereby drinking cups are cleaned prior to each use.
The abstract of this paper can be found here.

References: {1} Pickering et al. Am J Trop Med Hyg 2010, 82:270-8 [PMID:20134005].