Hi Boyce, I didn't realize you were a closet chemist! (;-) The chlorine in the water treatment chemicals is very different from that in sodium chloride (common table salt). The chlorination compounds for killing bacteria in drinking water are very reactive, and we used to use essentially the same stuff as Clorox (tm). Now they tend to use more stable substances that are also quit reactive, called N-chloramines. Chlorination is done at the parts per million level (as far as I can remember from 50 yrs ago!). Sodium chloride is unreactive, and becomes a problem for plants at the parts per thousand level. Think of sea water. Too much sodium chloride is bad for you, too little is also bad for you. People have surmised that the ideal level of sodium chloride for living organisms is the level that was in the primordial oceans of this planet when our one-celled ancestors were beginning to evolve. Fluoride is even more unreactive than chloride in water, but in biological systems it gets used in places where it can sabotage metabolism Chemically unreactive but biochemically reactive. Fluoride compounds are used in public water supplies at (as far as I can remember) the parts per billion level, and solely to prevent tooth decay in humans who drink the water. In college, I worked summers in the laboratories of our local water department in my hometown. That was a looooonnng time ago! Decimal points may all have to be shifted a bit to the right or left, but the relative order will stay the same. Jim Shields, closet chemist leaning out of the peanut gallery ************************************************* Jim Shields USDA Zone 5 Shields Gardens, Ltd. P.O. Box 92 WWW http//http://www.shieldsgardens.com/ Westfield, Indiana 46074, USA Tel. +1-317-896-3925