Can you fit an pump to a gravity fed electric shower

[The Inspector]

The pressure in my area is low, I have purchased an electric shower which is mains water supplied, unfortunatley if any other tap is turned on the shower turns of the heater and the shower goes cold.
If I put a tank of sufficient size up in the loft could I then fit a pump to a single cold water gravity feed to give the required minimum pressure 1 to 3 bar (15 to 45PSI Approx).

 

[Softus]

This is a fine solution to a common problem.

Your alternative to a separate pump (having installed the new cistern) is to replace the shower with one that incorporates a pump, but the cost would be similar to that for a separate pump.

 

[chrishutt]

The pressure in my area is low.

The problem is not the pressure but the flow rate. You may be able to improve the flow rate, for example by making sure stop taps are fully open.