On a well and septic system, a running toilet costs you more than it would in town — in three different ways.
Why it matters more out here
A toilet that keeps refilling makes your pump cycle on and off all day and night, which uses electricity and wears the pump. It also sends a steady flow of clean water into your septic tank, which is exactly what a drain field does not need. Fixing it is inexpensive and worth doing quickly.
The usual cause
Water trickling into the bowl between flushes means the flapper or fill valve has stopped sealing. On well water with iron or sediment, those parts wear faster than they would on treated supply.
If the toilet rocks
Any movement means the seal underneath has failed and water is going into the floor. In an older rural home with a wooden subfloor, that leads to rot.
Low flush models help a septic system
If you are replacing anyway, a modern low-consumption toilet puts noticeably less water through your tank and field, which extends the life of both.