Esp8266 query

I want to do a project where I use 2 arduino u no boards and possibly 2 esp8266, I plan to use an app to control the esp8266 which will send signals to the arduino then from the arduino to a relay board to control 3 pumps, now from a different location I have a tank that will recover some water from those pumps and when that tank is full I'm thinking probably I could use an ultra sonic sensor to detect water level and then I would need it to send a signal back to the esp8266 that I was originally refering to which is located by the other 3 pumps.

So after the tank that is at another location is filled If I could get a signal back to the other arduino to tell the pumps to turn by means of wireless that would be good.

Can anyone think of a way I could do that.