Wow, .04 caused that?!? Does not bode well for me. I don't have a water softener in my house yet and my water is near unsafe levels from the tap, in the high 400's for TDS. U.S. levels are supposed to be max at 500. So even with all new filters I started at 0 but am consistently getting .01-.02 only about 50 gallons into the new filters AND membrane. Better find a water softener!!!