The normal way to use these copper cups is to fill the cup at night and allow it to sit overnight. Then, drink the water in the morning. The taste will probably change markedly. The taste is very fresh and clean.
Ayurvedic medicine claims there are many health benefits from drinking 300 ml., once or sometimes twice a day. The copper will oxidize so the cups should be cleaned once a week with a little salt mixed with lemon juice or vinegar. Just fill the cup with the mixture and let it sit for 15 minutes. Then, wipe the inside with a very cloth or sponge. Do not use anything abrasive.