This is in reply to the following comment.
but if Ayurveda recommends it.... – Poutnik
The following abstract is from Journal Health Popul Nutr. 2012 Mar; 30(1): 17–21."Storing Drinking-water in Copper pots Kills Contaminating Diarrhoeagenic Bacteria" by V.B. Preethi Sudha, Sheeba Ganesan,G.P. Pazhani, T. Ramamurthy, G.B. Nair and Padma Venkatasubramanian.
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.
The paper has tabulated results of Antibacterial activity of copper pot and also Physical and chemical parameters in a copper pot as shown below.
Antibacterial activity of copper pot on drinking-water inoculated with enteric pathogens.
The level of copper that had leached into the test samples was 177±16 ppb which was well within the WHO limit of 2000 ppb in the test samples (copper pot) after incubation for 16 hours .
Discussion as per the paper.
None of the test pathogens was recovered from drinking-water stored in copper pots even after enrichment culture.
The level of copper leached in the former is far less (177±16 ppb) than that in distilled water (~420 ppb).
Safety of leached copper does not appear to be an issue since studies have shown that the current WHO guideline of 2 mg Cu/L is safe , and the levels leached in the study were 1/20th of the permissible limits.
It has been observed in the present study that the other physicochemical parameters of drinking-water remain unchanged after copper intervention, which makes them amenable for public use.
Since ancient times Ayurveda has advocated the benefits of drinking water from a copper vessel.
when water is stored in a copper vessel for over eight hours, very small quantities of copper get dissolved in this water. This process is called “oligodynamic effect” and has the ability to destroy a wide range of harmful microbes, molds, fungi etc. due to the toxic effect it has on living cells.
The oligodynamic effect $^2$,
(from Greek oligos "few", and dynamis "force") is a biocidal effect of metals, especially heavy metals, that occurs even in low concentrations. The health effect was known in India for more than 2700 years as their ancient texts prescribe.
In conclusion,Ayurvedic system$^4$ of medicine has great antiquity, dating back to about 5000 years B.C. Its Materia Medica contain resources in the form of drugs derived from plant, animal, metal and mineral sources.Ayurveda system prescribes dose in limits and not in excess.