The SWS improves microbiologic drinking water quality.

The following results are from studies conducted by the CDC and our partners to document reduction of microbiological indicators (fecal/thermotolerant coliforms, and E. coli) in users of the Safe Water System.

Study Country	Results	Reference
Bolivia	Fecal coliforms were found in water from 39 (93%) of 42 wells and 33 (79%) of 42 usual home water vessels. Escherichia coli was isolated from water samples from 37 (88%) of 42 wells and 29 (69%) of 42 usual home water vessels. During the intervention phase, SWS users (chlorine and vessel) had substantially lower geometric mean fecal coliform colony counts (P < 0.0001) and lower geometric mean E. coli colony counts (P < 0.0001) than water from vessel-only users in all sampling rounds.	Quick et al, 1996 308KB
Pakistan	Baseline drinking water samples among intervention households were contaminated with a mean 9397 cfu/100ml of thermotolerant coliforms. After intervention the mean concentration of thermotolerant coliforms decreased by 99.8% among the intervention households, compared to an 8% reduction among controls.	Luby et al, 2001 270KB
Pakistan	At baseline, 71 of 75 stored drinking water samples were contaminated with a median of 20,000 cfu of thennotolerant coliforms per 100 ml. Seventy-two households (96%) accepted and continued to use the interventions. After intervention, 36 of the 47 household (77%) who had received the water vessel and bleach had no detectable thermotolerant colifoms in their water.	Luby et al, 1998 92KB
Malawi	Analysis of water samples demonstrated that there was a 69% reduction in the geometric mean of faecal coliform levels in household water among the group using the improved bucket. (Note: no chlorine was used in this study, only the improved container).	Roberts et al, 2001 274KB

Click below for a table containing data on the inactivation of several bacteria, viruses, and protozoa by chlorine.

Effect of Chlorination on Inactivating Selected Microorganisms

The SWS prevents diarrhea.

The following studies, conducted by CDC and our partners, are randomized, controlled trials that document diarrheal disease reduction in users of the Safe Water System.

Pakistan	71%	Luby et al, 2004. Delayed effectiveness of home-based interventions in reducing childhood diarrhea, Karachi, Pakistan. Am. J. Trop. Med. Hyg. 71(4).
Zambia	48%	Quick et al, 2002 114KB
Uzbekistan	84%	Semenza et al, 1998 285KB
Bolivia	44%	Quick et al, 1999 329KB
Bolivia Bangladesh	43% reduction 24% reduction	M.D. Sobsey, T. Handzel and L. Venczel, Chlorination and safe storage of household drinking in developing countries to reduce waterborne disease. Water Science and Technology Vol 47.

The SWS improves the quality of beverages sold by street vendors.

Street-vended foods and beverages, an integral part of urban economics in the developing world, have been implicated in cholera transmission in Latin America. To improve the microbiologic quality of market-vended beverages in Guatemala, the SWS, handwashing, and education were promoted among street vendors. We conducted 415KB a randomized controlled intervention trial among 41 vendors who received the intervention and 42 control vendors, comparing total and fecal coliform bacteria and Escherichia coli contamination of market-vended beverages, stored water, and vendors' hands. When compared with samples from control vendors, a significant decrease in total coliform (P < 0.001) and fecal coliform (P < 0.001) bacteria in samples of stored water and beverages sold by intervention vendors was observed over the course of the study. The vessel system was well accepted by vendors. This simple inexpensive system consisting of hypochlorite disinfectant, plastic vessels, soap, and education can significantly reduce fecal contamination of market-vended beverages.

The SWS improves the quality of bulk oral rehydration solution (ORS).

Oral rehydration solution (ORS) is lifesaving therapy for cholera and pediatric diarrhea. During a cholera epidemic in Guinea-Bissau, we evaluated the microbiologic quality of ORS prepared at a hospital and tested a simple intervention using special vessels for disinfecting tap water with bleach and for preparing, storing, and dispensing ORS (Daniels, et al, 1999 371KB ) . Few coliform bacteria and Escherichia coli were recovered from tap water used to make the ORS; however, mean pre-intervention counts of coliform bacteria (3.4 X 10⁷ colony-forming units [cfu]/100 ml) and E. coli (6.2 X 10³ cfu) decreased significantly during the intervention period to 3.6 X 10² cfu and 0 cfu, respectively (P < 0.001). Using bleach disinfectant and special storage vessels prevents bacterial contamination of ORS and reduces the risk of nosocomial transmission of cholera and other enteric pathogens. 

The SWS can be effectively marketed.

CDC currently works with 13 Population Services International Country programs to manufacture, distribute, and socially market the Safe Water System sodium hypochlorite solution product. This very successful partnership has sold over 12 million bottles of hypochlorite solution, specifically branded and marketed in each country. This sales chart from our first partnership country, Zambia, shows how social marketing and demand creation can lead to steadily increasing sales.

Short and medium-term use of the SWS can be enhanced by motivational interviewing.

A SWS program was initiated in Zambia with one group receiving the standard practice of health education (comparison group) and one group receiving Motivational Interviewing (MI) (experimental group). MI is a person-centered, stage-based approach to encourage change in personal habits by resolving ambivalence and eliciting a person's own arguments for change. In the first field trial, the majority of users used the system correctly (as measured by residual chlorine present in 71.1-94.7% of the households), but no statistical difference in usage rate was seen between the education-only and MI groups. A second field trial incorporated lessons learned by improving the MI training and resulted in significantly higher purchase rates, with an average of 0.71 more bottles per month in MI households than education-only household, of the disinfectant in the MI group (Thevos, et al, 2000 170KB ) . A third field trial again improved the MI training, and compared MI with social marketing. Indicators of safe water practices (including residual chlorine levels in households) and knowledge improved dramatically in the MI group as compared to social marketing alone (Thevos, et al, 2000a 200KB) . Follow-up work 16 months after the third field trial showed that the MI group still had double the rate of correct use of the SWS as measured by chlorine residual as the social marketing group alone (Thevos, et al, 2002 61KB ) . Thus, MI is a promising method for motivating the adoption and sustained use of safe water behaviors.

Water stored in clay pots can be effectively treated with sodium hypochlorite solution.

Ogutu et al, 2001 212KB demonstrated that turbid, contaminated source water stored in clay pots can be adequately disinfected using chlorine in laboratory and household settings.

If you have experience with any of these or related issues, we would like to hear about it. Please email us at safewater@cdc.gov.

1600 Clifton Road, MS-A38
Atlanta, GA 30333
Phone: +1(404) 639-0231
Email: safewater@cdc.gov