Fitting a new washer may not be the right solution every time for a dripping tap. Sometimes the valve seat may also be damaged. The valve seat is the one the washer closes onto when you close the tap. The pressure of water under the washer forces itself between the seat and washer. Over time the water even erodes the brass seat. Little channels get formed in the seat, which cause the water to flow between the washer and seat causing the tap to drip. In areas with hard water it will be harsher

Here we explain how to regrind a tap valve seat.

You can remove the small channels in a tap seat by grinding the rest of the seat down. It produces a flat and smooth seat for the washer to sit on and seal the flow of water. A seat grinder is a very simple tool. It is normally supplied with different sized serrated cutters and screwed location bushes. These help to position the cutter central on the tap seat.

The one that just fits through the opening of your tap will be the correct size serrated cutter for your tap, and correct size bush is tightened in the threads which held the tap valve.

Here is the step by step process of how to regrind your tap:

• Insert the grinder in the top of the tap. Fit the thread of the bush in the screw thread and tighten it.
• While pushing down on the handle, twist the grinder against the tap seat. Twist clockwise so that the cutter tightens on the shaft.
• Remove the grinder periodically and look at the seat. Any imperfections in the seat will stand out as dark areas. Keep grinding until the complete circle of the seat is in a bright brass color.
• Finish with a few, full revolutions of light pressure give the seat a final polish.
• Replace the valve with a new washer in the base of the tap and fit the handle. Do not close the tap.
• Turn off all other taps which were opened.
• Turn on the water supply to the tap and allow water to flush through it. This will remove any debris remaining in the tap after grinding the seat.