I was recently doing some film developing calibration runs having discovered a film densitometer I could use at work. I live in Southern California, where the tap water is frightening stuff. Having eliminated the other suspects I had begun to believe the water was causing my unusually long development times, very different than when I last calibrated my film developing back on the East Coast.(posted 8089 days ago)Not much on this subject was found in my books on developing and my Internet searches didn't turn up anything definite, although I admit I am not a very talented searcher. I can't recall if it was in this forum but I read a thread asking about anything that might be in tap water that could interfere with B&W film development. One of the answers came from an amateur photographer who is a chemist in the day-time. His answer was, "It depends on just how bad your water is," but gave no specifics.
It turns out that Kodak has a technical information phone number (800-242-2424, extension 19) where you actually get a human being on the phone almost immediately. He was able to tell me a number of recommended maximums for various tap water components.
The most important of these, he said, is total hardness as calcium carbonate. Kodak suggests this be in the range of 40 to 150 ppm, with 40 being the preferred end. Too high a level limits the swelling of the gelatin and leads to delayed entry of the developer.
A call to the Huntington Beach Water Dept yielded a fairly detailed analysis of the water (they check it all the time). Calcium carbonate was 161 ppm, well over the recommended upper limit. So my developing mystery may be solved.
On one of Kodak's web pages they note that good results may very well be obtained despite hard water and it was suggested to compare film developed with distilled water with that developed using tap water. I haven't had the chance to run these tests yet. I'll post numbers when I get them done if anyone's interested. (It'll be a few weeks, though.)