BELLEVILLE, N.J. (CBSNewYork) — Police in one New Jersey town have issued a public safety warning.

The Belleville Police Department says people are knocking on doors throughout the community and posing as state or town workers checking water filtration systems.

The scammers then urge residents to spend thousands of dollars on what they say are “necessary” repairs to their water service.

Police say residents should never let a salesperson inside their home without a scheduled appointment.