Help! build network (1 node :low power )

Hello,

What ideas do you suggest for measuring of water level in a well; most of the time the reading is not crucial but to know how much is left in it(for a month or so) but it is essential when im filling water in, so i need to know how much water is in(filling takes about 14-24 h). I think measuring water level with an ultrasonic distance device. as it is very hard to install any other hardware inside (more than 4m depth "10 feet "). And I will need the data to be transmitted to some other arduino to be read on a screen, a web page, or anything else. what do you think ?

This device(reader) will be part of a small network to build, consists of few nodes, all can be plugged in to power, but the one in the well would run on batteries. I wanted to take your advice about whether to be an arduino with nrf24, esp, wemos, or nodemcu ? which is more power efficient( changing batteries will be hard).
other nodes will do simple latching, making small iR transmitting, and so on.
I thought about Blynk, any better ideas ?
thank you for your time.

For the radio nodes, look at JeeNodes. That guy has sensors in his house that run for years on a single battery.

How wide is this well? I'm guessing that an ultrasonic sensor in a narrow pipe will work differently to one in a water tank.