A seat contained inside the valve of a domestic tap, can and will wear with the constant use and age of the item. You may have replaced the tap washer as a matter of course, yet you can see the water still dripping from the tap. This could mean you need to replace the valve seat. It could be damaged by limescale and various other foreign objects that can find there way into these type of systems.Regrind the valve seat.This is quite an easy job to do is a simple job and is done using a reseating tool. Available from DIY stores and plumbers merchants. Enfield Boiler Repairs use this tool.Isolate the water supply to the affected tap. Both taps shuld be opened to drain the water away so you can work. Remove the tap head by removing the cover if there is one, and releasing the retaining screw. Tap designs can differ greatly and each one may have a different removal routine, so use the best for your style of type. Screwing the reseat tool into the opening, adjust the cutter to make contact with the valve seat. Then be smooth by turning the tool handle.Seating Set.A piece of kit call a valve seating and jumper set can be bought or hired. An Enfield Boiler Repair plumber is trained to work with these items. A new valve seating made from plastic is set in the seat. You can now refit the new washer and also the new jumper and also the new washer. Reassemble the tap and replace the tap cover. Turn the tap on and off. This will bed everything in so it works ok. It may take a couple of days so dont worry if it still drips slightly. When you’ve finished switch on the water supply. Test each tap and allow the water to flush through.