My Kohler Portrait toilet (a little over a year old) has a slow leak which has me baffled. It refills every 1/2 hour or so. I shut the water off to ID the source of the leak – result was that the water level in the tank dropped about 3 inches then stopped. I had the identical problem in September (only then the water dropped farther – to the middle of the tank), and at that time I replaced the entire refill valve mechanism. It worked for a few months, but now I’m back to square one. ANY IDEAS (1)WHY THIS KEEPS HAPPENING, (2) WHAT IS CAUSING IT, (3) HOW TO FIX IT SHORT OF REPLACING THE REFILL VALVE EVERY FEW MONTHS.
Have seen same problem a couple times where the tube that discharges water into the overflow stand pipe of the flush valve is siphoning water from the tank. Problem was solved by making sure the discharge end of that tube is higher than the water level in the tank. Hope that works..