Well Level Detector

How about a cork on a piece of string?

blairlakehead_@hotmail.com says...

Well drillers and maintainers typically use a sonic device at the well
cap (think sonar), such as this:

http://www.globalw.com/products/wl600.html

--Gene

Blair

I have been instrumenting wells and water tanks for several decades.
You can select a wide variety of solutions.  The major issues are
accuracy and frequency of measurements, and if there is anyother
equipment down the well.  Any yes the cork and string could work,
though you might not be satisfied with the data quality.

Sonic probes can be problematic in wells because of the relatively
small diameter resulting in less that ideal accuraccy.

If you need measurements once in a while - as much as daily a steel
tape with weight and chalk is highly accurate.  Alternately a low
voltage resistor probe with a calibrated and marked cable works
effectively.  See the link below.  There are other maufacturers.  This
is the piece of equipment that well drillers, hydrologists,  and
environmental scientists would typically use.

http://ken-tech.net/index.html

If you need frequent measurements then you might consider a stand
alone downhole data logger.

http://www.in-situ.com/

If you need to tie the data into a data automation process then you
get into the a different realm.... of PLC automation.  Which is
another story..

Hope this helps

Best of luck

Steve