Abstract: Apparatus for use in high pressure underwater abrasive-laden water jetting has a gun connected to a high pressure water pump and having an inductor connected to a source of abrasive. Abrasive is supplied to the inductor only when the gun is operated by reason of a control valve for an air supply to the abrasive container being opened to pressurize the container when water pressure is supplied, in other cases air continues to flow to prevent water entering the apparatus.