Drinking water (particularly anything that tastes halfway decent) has a lot of minerals in it. Try drinking some distilled water and you will know what I mean.(posted 8514 days ago)For mixing developers (film or print), it is best to use distilled water or filtered water. I just bought a gallon of distilled water for $0.59 at Kmart. The Brita water pitchers with filter work fine. I wouldn't worry about the water for any other solutions, except for the final film rinse, which should be distilled water mixed with Photo-Flo wetting agent.