My toilet makes a `phantom flushing` noise every so often day and night. The water runs in the toilet slightly but it doesn`t actually flush. It is a Kohler and I believe it is a water conserving unit-it was in the house when we bought it 9 years ago but only the last year or so it has been doing this noise.

The flapper valve needs replaced.

Not sure? Put a few drops of food coloring in the tank... bet you find colored water in the bowl in a few hours at most as it leaks into the bowl.

They cost less than $5 at Lowe's or Home Depot. And don't last forever.

Asuming its not a pressure flush unit, but a gravity flush.

Do you have hard water? Open your toilet tank and check the rubber flapper/stopper (I don't know the technical name) that closes the hole at the bottom. You are looking for reasons that may not have a good seal to close off the flapper and stop water leaking through after you've flushed, which is what's making this partial flush sound. There are a few reasons it might not be. Check for build up of sediment in tank. You'd need to clean that out if that's the case. Also clean around the entire edge of the flapper or replace with a clean new one. If heavy sediment is a problem you ought to get your water fixed. If, however, the water in tank and bottom of tank is all clear, also check your chain that attaches between that flapper and the handle that flushes the toilet. If it's too long it may be dangling under edge of flapper and causing a slow leak of sorts.