The kidneys are responsible for metabolising water. They are related to the reproductive system, urinary tract, blood, skin and nervous system. The kidneys are weakened by lots of fun things like alcohol, sex and travel, and also antibiotics, ignoring the urge to wee and drinking too much or too little water.
Most important is water. Chlorinated or distilled water won't help. Spring water or rain water is much better. But perhaps one of the biggest problems is cold water, drink water at room temperature or even warm. Cold drinks actually heat up the body in the long term cause the body starts to produce heat to counter the cold. Warm water on the other hand makes you sweat which cools you down and releases some toxins too.
Water which is very high in calcium can cause kidney stones, and avoid too much acidic food (spinach, tomatoes, radish) because this will inhibit the bodies ability to absorb calcium, leaving it to clog up your digestive system
But the 'water' that the human body is primarily composed of is not just water, it is an oily solution. So take plenty of good quality fats like olive oil, coconut oil and ghee to strengthen and rejuvenate your body. This will help to rebuild good blood, and therefore help your skin too.
To regulate your metabolism take cooling digestive spices like turmeric, cumin and coriander every day. All three are very mild and can be added to almost anything in small amounts without hugely changing the taste. Coriander (fresh or dry) is especially good for as it a gentle diuretic and so will cleanse the kidney. Steep coriander seeds in hot water and sip all day.
Kidney infections, urinary tract infections and kidney stones are all closely related, and can be very very painful. A weakness in the kidneys is often hereditary. Special thanks to Dr David Frawley, he's a real good 'un.