Storing Drinking-water in Copper pots Kills Contaminating Diarrhoeagenic Bacteria

Abstract

Microbially-unsafe water is still a major concern in most developing countries. Although many water-purification methods exist, these are expensive and beyond the reach of many people, especially in rural areas. Ayurveda recommends the use of copper for storing drinking-water. Therefore, the objective of this study was to evaluate the effect of copper pot on microbially-contaminated drinking-water. The antibacterial effect of copper pot against important diarrhoeagenic bacteria, including Vibrio cholerae O1, Shigella flexneri 2a, enterotoxigenic Escherichia coli, enteropathogenic E. coli, Salmonella enterica Typhi, and Salmonella Paratyphi is reported. When drinking-water (pH 7.83±0.4; source: ground) was contaminated with 500 CFU/mL of the above bacteria and stored in copper pots for 16 hours at room temperature, no bacteria could be recovered on the culture medium. Recovery failed even after resuscitation in enrichment broth, followed by plating on selective media, indicating loss of culturability. This is the first report on the effect of copper on S. flexneri 2a, enteropathogenic E. coli, and Salmonella Paratyphi. After 16 hours, there was a slight increase in the pH of water from 7.83 to 7.93 in the copper pots while the other physicochemical parameters remained unchanged. Copper content (177±16 ppb) in water stored in copper pots was well within the permissible limits of the World Health Organization. Copper holds promise as a point-of-use solution for microbial purification of drinking-water, especially in developing countries.

Incorporation of copper nanoparticles into paper for point-of-use water purification

“…Although many studies have shown the antimicrobial effects of copper surfaces in hospitals, the use of copper in drinking water treatment, has been limited to silver-copper ionization systems for the control of Legionnaire’s disease (Stout and Yu, 2003) and copper pots in developing countries (Sudha, 2012). At the material cost of only a few cents per filter, one sheet of CuNP paper can be synthesized in the laboratory.…”

“…Recently, for POU applications, we have designed a paper sheet embedded with silver nanoparticles to purify drinking water contaminated with bacteria (Dankovich and Gray, 2011a; Dankovich, 2014). As a more affordable alternative to silver, researchers have turned to using copper to purify drinking water (Sudha et al, 2012; Stout and Yu, 2003; Varkey and Dlamini, 2012). …”

“…Copper and copper compounds have been demonstrated to eliminate a wide variety of microorganisms, including Vibrio cholerae, Shigella, E. coli, Salmonella, fungi, viruses, and other types (Sudha et al, 2012; Esperito Santo et al, 2011; Molteni et al, 2010). Metallic copper surfaces have been used to prevent bacterial growth in hospitals (Esperito Santo et al, 2011; Molteni et al, 2010).…”

Microbiological Quality of Water Stored in Copper, Earthenware and Stainless Steel Vessels

“…Sudha et al, (2009) reported that water stored overnight in copper pots gave no counts for E. coli, S. typhi and V. cholerae, demonstrating inactivation of these bacteria. Sudha et al (2012) Use of copper in history is found to be about 10,000 years ago. In 3000 B.C., copper ores were found in the island of Cyprus.…”

“…The mechanism of action of copper on bacteria is not completely understood (Sudha et al, 2012). Some studies conclude that the copper ions brought about complete killing of bacteria by membrane damage (Santo et al, 2011).…”