air lock in kitchen sink tap. How to resolve?

Question

I have a cistern in the attic that distributes water through the house. Yesterday there was no water for awhile (mains turned off) and so when the cistern refilled we now have just a trickle of water in the kitchen tap. It starts off with a gush if we havent used the tap for awhile and then reduces to a trickle. Its an ordinary cold water tap. How do I get rid of the air lock? Other taps are all working fine and water is full in the cistern.

Answer 1

With all other taps closed, open the problem tap just enough to get the water flowing, leave it open until the water flows in a steady stream with no air bubbles.
If you have access to the pipe, gently tap it when the tap is open, this may help break the air lock.

Answer 2

I don't think you have an air lock. It sounds more like there is an obstruction in the pipe, and some air trapped between the obstruction and the tap.

Water can slowly build up pressure, compressing the air. When you open the faucet air pushes out water until its pressure is reduced. Then water trickles out.

If you could pressurize the tap from an outside source, perhaps you could blow the obstruction out of the way. An air compressor could do it, or a water pump.

Otherwise, and if I am right about the obstruction, it seems you might have to disconnect some piping to find the obstruction.

Does the kitchen cold water tap come from the same piping as taps in the rest of the house? If so, and I am right about the obstruction, it simplifies the search.