Copper has an electromagnetic energy known as "prana shakti", which essentially means "life energy". This quality is the key reason why Ayurvedic medicine recommends storing water in a copper vessel.
When water is stored in a copper vessel, the "prana shakti" in the copper infuses and energizes the water. Copper infused water, which is known as "tamra jal", helps balance the three doshas and maintain a health pH balance in the body.
Meenakshi Gupta, a prominent Ayurvedic practitioner, wrote a very interesting article canvassing the reasons to try drinking water from a copper vessel. In that article, Ms. Gupta notes that the ancient practice is experiencing a modern reemergence:
"During my childhood days I remember my grandmother storing water in a copper vessel overnight and asking us to drink from it first thing in the morning. She claimed the water stored in a copper vessel was extremely healthy for the mind and body. Now when I see these ancient customs reemerging & my own findings with the healing ideologies of Ayurveda, I look back and think that I should have taken my grandmother’ s advice more seriously."
As Ms. Gupta writes, copper has amazing anti-microbial qualities, stimulates the brain, aids in weight loss, slows aging, and can even help fight cancer. It is so lovely to see ancient holistic practices reemerge!
You can find Ms. Gupta's full article here.