of course distilled water is highly recommended for keeping the kidneys flushed. i hate to sound like some evil scientist, but i would like to see OP tried alone without changing anything else so that we have a degree of control over the "experiment". but if i were you, i would do the water and salt regimen according to the Water Cure - http://www.watercure2.com - because kidneys only come one set to a customer.
i also recommend the barefoot herbalists kidney cleanse. i have had trouble with my kidneys since a teenager and i got through half a bottle of his kidney cleanse and havent had a lick of trouble since. and i still have the other half of the bottle in the fridge in case i need it!