Rolf,
Nothing about transmitters but some thoughts:

I can view the first photo but not the second.

No electricity in the well? Where is the the pump? I am wondering if you 
can measure something about the pressure in the pipe before the pump  in 
the house? Wouldn't work with a jet pump at the bottom of the well 
unless there was a check valve in the house but the priming issue makes 
it sound like there is a pump in the house that "sucks" the water up, so 
you could just measure the "suction" while the pump is off for an 
accurate water level, all done from inside.
Of course you NEED a pump at the bottom if the well is more than ~10 
meters deep.

I bet you could sneak a wire for an antenna past the manhole cover 
without drilling - or copper tape, etc.

Could you resonate the air cavity above the water to measure the level?
Ommmmm.



A weighted tube to the bottom of the well, open on the bottom, filled 
with air (or water, etc), attached to a pressure guage at the top  of 
the well? The tube could even come into the house

An insulated cover over the man hole so he won't have to de-ice it to 
inspect the water level? (I know, not at all sexy or PIC or EE or 
anything remotely like that)

-- 

Looking forward,
Al Shinn



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