Nearly a tonne of metal has been stolen from fire hydrants across western Sydney in a few months, rendering some inoperable.
Fire and Rescue NSW has found 38 hydrants with missing components from apartment buildings and other sites across a dozen suburbs since November.
The missing parts are mainly brass and copper fittings, which are valuable when sold for scrap metal.
FRNSW and police have identified the removal of about 850kg of metal fittings, which can sell for as much as $10 per kilogram.
One plumber, aged in his 40s, has been arrested and charged with 18 counts of theft following the hydrant-stripping.
The fittings were important structural components and their loss might render the hydrants unusable and firefighters unable to properly respond to emergencies, authorities said.
FRNSW Chief Superintendent Steven Hayes urged residents and workers to contact police if they see any hydrants with missing parts.
"Without those fittings the fire hydrant system may not be operational, which places residents in potential danger and delays firefighters," he said.