Speak to any kidney doctor and you will be told plain water is still best. Everything else has to be processed and toxins and wastes removed by the kidneys.

As a side note, my husband is on kidney dialysis. We have learned a whole lot about kidney disease. 1 out of every 8 people have some degree of chronic kidney disease and 50% of those don't know it. A simple blood test can tell you how well your kidneys are working. By the time you get symptoms, it can be too late to halt the progress of the disease.

It was actually my mother's kidney specialist who told us that a healthy person with healthy kidneys has no need to drink water without stuff in it. He pointed out that all water has particulate matter (that is "stuff") in it. In fact, only "distilled" water, he pointed out is "pure" water and that if you try to drink distilled water it tastes flat and unpleasant. He said all but very impaired kidneys have the ability to process the water in food and other beverages and there was absolutely no truth to the myth that the "processing" for tap water is any "easier" on the body than pulling it from fruits and vegetables and beverages. Even though my mother has only about 50% kidney function, he said there's no need for her to avoid coffee or drink her water plain. He told her to avoid low carb dieting because it could stress the kidney's, but that and the maximum of 3 quarts of liquid are the only restrictions she was given.

My aunt has polycistic kidney disease, and her kidney specialist told her that she did have to know what a beverage contained before she drank it, because she couldn't drink anything with sodium or protein in it (so most soft drinks were out, as well as milk). Water, he told her, was the "safest" beverage for her to drink as long as she knew it hadn't been through a water softener (which adds sodium to the water) but also said that there was no reason that she had to drink water "plain."

I only have the two kidney specialists' advice to go by, but I would suggest that anyone who has concerns, ask a kidney specialist directly.