there can be upto 1/4 oz of silver in a gallon of spent fixer.
its mainly the silver in the fixer that isn't good to go down the drain.
if you have metal pipes it may corrode them if done for a long enough time ...
and the silver likes to kill off beneficial bacteria in home septic and municipal sewer systems.
25+ years ago kodak used to say to just drain it because it posed no problems but they now
say not to dump it down the drain and to remove the silver from it ...
don't worry about a hornet's nest HFT III likes to assume different user names
and go on and on about politics ...
in a previous thread he said spent fixer was harmless, but later he added
he used it as a herbicide on his property.
i hope he gets his well water tested
if you have any magnet questions &c feel free to PM me
i sell them as well as other stuff to recover the silver in your fixer.