Police in Sheffield are urging residents to be on their guard against bogus callers taking advantage of a problem with discoloured water.
Some residents have reported problems with discoloured water this week, and engineers are trying to rectify the issue.
A South Yorkshire Police spokesman said: “One of the most common methods for distraction burglars is to pose as Water Board officials and ask often elderly or vulnerable victims to run taps to check their water.
“But Yorkshire Water staff do not need to enter properties as a result of the discolouration, so do not open your door unless a caller has an appointment. All Yorkshire Water staff wear uniform and carry photo ID cards.”
Call Yorkshire Water on 0800 138 7878.