I was cleaning the garage abut two weeks ago and noticed a slow drip on my Whirlpool WHES30 water softener's digital display. I replaced the washers in the shut-off valve under the kitchen sink, as they felt damp, and it went away. A couple days later, it started again, so I checked the guest bathroom(rarely used), found a little water under the sink, changed those washers and the drip display stopped again. A couple days later it started again. I replaced all the washers in all the angle stops, the shower valves, the toilet flappers, checked under the dishwasher for leaks- nothing stopped it. There's a counter on the softener in the program, cycles from 000 to 199- that's a gallon. Using a stopwatch, I figured it was about 13 gl./hour. After driving myself nuts for a week, got a plumber out here yesterday to use CO2 to check for a leak in the pipes. The pipes are under the slab- he listened all over the house for hours using his ears and a listening device- thought he heard some bubbles coming up from near the sink in the kitchen, drilled a hole in my Saltillo tile groutline throught the slab, inserted a probe that came up muddy. He was all set to come back tomorow and jackhammer the floor to get at the leak. I've been shutting the main ball valve on and off as need be because th water appeared to just be draining down into the soil- no evidence of water anywhere in the house. Came back from running today, turned on the water, took a shower, drank some water, got a call from a friend, forgot to turn the main back off right away and lo and behold, when I went out to do that, the display drip had stopped. The water has been on for hours now and no display. The only thing I didn't check were the washing machine valves because I couldn't get them off. I had turned the hot and cold gate supply valves off a couple days ago so I haven't done any laundry since then. Don't hear water running under the sink anymore, which I did when the display drip was showing. Could it be the washing machine valves?