How to take care of kidneys?

Water.: Without knowing more specifics about your request; the best way to insure proper renal(kidney) function is to maintain adequate hydration; drink plenty of water!

Kidney care: Exercise regularly, eat sensibly with lots of fruits and vegetables, less meat, more beans and legumes, don't smoke, and don't eat alot of salty food or use a salt shaker. That's right, your kidneys are in large part an extension of your cardiovascular system, so caring for them is just like caring for your heart.

Salt and Protein: Without fully understanding your question, in general, kidneys are healthiest and happiest if they are given a little extra water, and, no excess salt or protein. Excess salt and protien are just extra work for kidneys.