Attwood S3 Digital Bilge Switch

These operate really well, and have no moving parts. The whole switch is about 2" tall, and that silver circle on top is one of the contacts that detects the water, which should give you an idea when it will activate depending on the space you mount it in. The other contact is underneath the "tent" portion of the switch. The switch runs for between 8 seconds (if it's been run recently) to 60 seconds (if it hasn't been powered in 6 months or more) when it first turns on, so be aware of that. It will also run for 60 seconds AFTER the water level no longer touches the contacts, so be careful to use a pump that can be run dry, or mount the switch a bit higher than the pump to allow the pump to stay submerged when running. Saved my bacon during some recent power outages. :)

thought the leads were supposed to be 36 inches. Had to double splice the wire to reach the hole. Now it works great