The partial negative charge in a molecule of water occurs because

the electrons shared between the oxygen and hydrogen atoms spend more time around the oxygen atom nucleus than around the hydrogen atom nucleus

force required to detach it is given by

charges are taken to be fundamental charge

now we have

so above is the minimum distance at which it will detach

distance = 150m

displ = root (50 ^2 + 100^2)

root(2500+10000)

root 125000