recommedation for ultrasonic water level sensor?

Other Hardware Sensors
2

http://www.newark.com/freescale-semiconductor/mp3v5010dp/ic-pressure-sensor-0-to-10kpa-1351/dp/14R8944

This has a range of 0 to 1.45 PSI or 0 to 1019mm of water. Connect a tube to the port and anchor it to the bottom of the tank and it will have a 0 to 5V output based on the water level.