I have an issue with occasional banging in the water pipes that only seems to occur when the water is turned off at a tap. No specific tap, it could just as easily happen when the washing machine takes in water and then stops. My wife thinks that it only happens when the cold tap is turned off and that it happens more when the tap is turned off sharply. I have noticed it when I have turned off a hot tap but it could be that some water is being drained elsewhere in the house. I have no spluttering from any tap throughout the house nor is there any noticable loss of pressure. We are mains fed and have a combi boiler and, therefore, no water tanks. My first thought was air in the system but I would have expected spluttering somewhere. Any ideas please????? Steve