The central North Island town of Raetihi has its drinking water back, but some locals fear more problems could arise if the council does not overhaul its water scheme.
Residents have not been able to drink or cook with the water for the past three weeks, after thousands of litres of diesel spilled from a tank into the supply.
Raetihi's water supply has been contaminated once before, from a fuel spill in 1979.
However, resident John Dobson says he knows of about four other unreported incidents and he believes there will be more unless the water scheme is changed.
He wants Horopito Spring to become Raetihi's new water source and has started a group to push for the change.
Ruapehu District mayor Don Cameron says his council will look at the water schemes for the wider area, not just Raetihi.