A team of Indian and Australian researchers has found that water, if stored in copper vessels for about 24 hours, get purified as the harmful bacteria present in it become inactive or dead. To find out if the inactive bacteria get active when someone drinks the copper treated and purified water, the researches fed this water to rats and there were no signs of any infections caused by the bacteria present in them. (http://www.abc.net.au/news/2010-07-19/copper-container-storage-reduces-water/910208)
The researchers have tested the anti-bacterial effects of copper against bacteria like Salmonella, Typhi, Salmonella typhimurium, Vibrio cholera and E coli. They found that copper can kill these harmful pathogens present in contaminated water. Not to forget the copper details as stated. Copper vessels should be as pure as 95% and 5% zinc if not; these copper vessels cannot kill the harmful pathogens present in water. The whole study has been conducted with 99 % copper vessels.
However, this fact can even prove to be detrimental if the vessel is not cleaned and washed regularly. Make sure that the container is scrubbed and rinsed well and ensure that there are no deposits left in it.
Storing water in copper containers for longer period is not good, Storage of water for eight to 10 hours, that is enough time to inactivate most of the bacteria