Float switch, and other point level sensors, are great alternatives to the more expensive continuous level sensors (ultrasonic, radar, level probes, etc.). Functionally, of course, they are not as capable. However, they work great under the right circumstances and continue to be a staple in level measurement applications throughout the world.
APG, Automated Products Group, sells sensors utilized by lift stations in wastewater treatment plants. There are many sensor solutions on the market, ranging from simple float switches to sophisticated ultrasonic sensors.