Liquid level sensor

: A friend of mine asked that I search the Internet for a product that would meet his needs. He needs something that will sense a rising water level (or any other liquid, for that matter) and turn on a pump to evacuate the pipe. It needs to recognize the difference between a quick spash versus a rising level of water and only run the pump when its really needed. He is specifically looking for a sensor that hes heard about thats placed on the outside of the horizontal run of pipe and doesnt need to have a hole cut to insert a sensor or float. Do you know of anything out there that does what hes talking about?Thad, I think your friend is probably after a a float switch which is usually part of a pump or you can buy the float switch separatly if he allready has a pump or there is another alternative which consists of a couple of probes which hang vetically into a sump or pit and basicallydo the same thing as the float switch ie: when the sump is dry pump doesnt pump and when water is in the sump either the probes or the float switch senses that there is water there and the pump switches on .. when the water is gone it switches off ……..any pump supplier should be able to advise …. good luck.