Homeowner Forum / Construction / September 2005

A variation of this might be a pipe running from the top of the tank up
to the surface. Inside that would be another rod with a float on the
bottom. As the water level rises, the rod would raise up accordingly. If
you could find some clear tubing, you could mark the high and low marks
on the tubing. Otherwise, you could cut the outer pipe at the low mark,
and fasten a board or something behind it that you mark the high mark on.
Of course, you'd have to figure out a way to keep bugs and debris from
entering the measurement pipe.

Another option might be to modify an automotive fuel sender (never used
for fuel, of course). You could make the float arm longer so it can
adjust to larger rises and falls if needed. Then a simple 12 volt line
running to a standard fuel gauge and a 12 volt power supply. It may not
be super accurate, but probably close enough to get an idea where your
water level is.

Good luck,

Anthony

Except if the seal at the bottom of the indicator tube fails and water leaks
out.  You do need a hole at the bottom and this might not be easy to make.

A tube over the top edge and into a tall clear cylindar would make use of
the siphon effect to match the levels but if it ever went too low, the water
seal would break and the siphon tube would empty and the indicator would
stop working.

I might try a float on top of the water connected to a cord that runs up and
over a pully and then down to a counterweight (heavy enough to keep the cord
tight but not enough to lift the float off the surface of the water).  This
will result in an inverted indicator (full at the bottom) unless you use two
pulleys.

For slightly more $ but not a lot would be one of those laser measuring
tapes.  You may need to float a target on top of the water but once mounted,
you would get a precise measurement at the touch of a button.

All depends on how much room you have to build it and how accurate/reliable
you need it to be.