In a rental property, a running toilet is not just a water bill — it is something a guest will mention in a review.
The quiet running one
If you can hear water trickling into the bowl between flushes, the flapper or fill valve has stopped sealing. Inexpensive part, quick visit. In a house that stands empty for weeks it can run a very long time before anyone hears it.
Heavy use in season
A beach house toilet does more work in one July week than a family bathroom does in a month. Handles, flappers and fill valves wear accordingly, and it is worth checking them in the off season rather than during a changeover.
Salt air reaches the fittings
Supply lines, shut-off valves and bolts corrode faster here. If yours are original and looking rusty, replacing them during a routine visit is far cheaper than dealing with a failure while guests are in.
If the toilet rocks
Any movement means the seal underneath has gone and water is getting into the floor. In a beach house on pilings, that means water into structural timber, so it is worth dealing with quickly.