Quick answer
This is a serious warning sign. Switch off your electrics at the consumer unit and call an electrician immediately. Do not use water or metal fixtures until it is investigated.
A tingling or shock sensation from a metal tap, pipe, radiator, or appliance casing is a serious electrical safety warning. Do not ignore it or assume it is a minor nuisance. It means electricity is reaching metal parts that should not be live — possibly because the earthing is faulty, bonding is missing, or an appliance has developed a fault. Switch off the main switch at your consumer unit and do not use any electrical appliances, taps, or metal fixtures until a qualified electrician has investigated. Call an electrician as an emergency — this is a genuine risk of electric shock or worse. Do not reset anything or try to investigate yourself.
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