My toilet works fine but I noticed every half hour or so it starts running(filling)for about 10 seconds. It doesn't appear to be losing water but as I said it everyso often runs by itself for 10 seconds and shuts off. Dave

Dave:---The reason why your toilet cycles on every once in a while, is because water is leaving the tank. When the water level finally gets low enough, the ballcock opens up to fill the tank, and then shuts off again.
Replace the flapper, and examine the seat that it seals up against for roughness or irregularities. By a quuality flapper (some are guaranteed for 5 years) follow instruction, and watch your water bill go down...Bud

• Toiletology 101