I am helping a friend protect the pump for his above ground cistern by adding a water level sensor. It is actually 2 cisterns under their deck connected together via about a 3" pipe. To keep it simple I am suggesting adding a saddle Tee and with a riser pipe attached (see drawing) and sensing the water level in it. They generally draw on one cistern at a time by closing one of the valves. There is very little head space between the cistern top and the deck so inserting anything long in the riser pipe is not easily done. I expect to use a 1.5 to 2" diameter riser pipe. To keep maintenance easy I want the switch to handle the 125 VAC direct to the pump. I have looked into optical and non-contact sensors but I would like to get opinions from TBN first. Any suggestions are welcome.