If air is allowed into a water supply system, it will mass at high points and will have a restriction on the water flow and can block it entirely. If there is not sufficient pressure to move the air through the pipework, the air lock will stay put until the pipework is manually cleared. To remedy this, you should find the tap that has the restricted water flow, and connect a length of rubber hose to it, and the other end to a working direct feed tap. This will normally be the cold tap at the sink. South East London Plumbers solve airlocks. With the hose connected, you should open up both taps at the same time to let the pressure of the mains water to force the air back out of the pipework. Run them for several minutes and then turn off, shutting the air locked tap first. It can take a few operations for this to release the air. When finished, undo the hose, the higher tap first, then the lower and drain the hose. If More Than One Tap Is Affected, it should be cleared starting with the lowest tap. It is possible to blow the air out of the pipes, by pushing a length of hose in the outlet pipework within the loft cylinder. Open up the tap at the other end and blow through the pipe to try and dislodge the air. Draining Down An Air Lock is a last resort. Isolate the water feed and open all the taps to drain all the water. Turn all taps until they are about a three quarters shut. A South East London Plumber can carry out this job. De-isolate the water, and adjust them all to achieve a light even flow rate. Beginning with the lowest and working upwards, open the taps up one by one to the half-open position. Then, again at the three quarters open position. Once all air has been removed, turn all taps off to a point where there is only a minimal flow.