How do I make a waterproof access hatch by a bath?

[JACR]

I want get an electric shower over my bath.

The trouble is I have an access panel/door on the wall that the bath is against which gives access to the hot water tank. The access is a mirrored door on a hinge which is flush with the surrounding tiles. The rest of the area around the bath is all tiled so it is all waterproof except for the small gap around the edge of the mirror-door.

Does anyone know of the best method to seal this gap around the door and still allow access to the tank?

[Guy King]

The message from "JACR" contains these words:

How often are you likely to want to get in there? If it's infrequent, silicone and cut through it with a Stanley knife when you need to get in.

[Ian Stirling]

silicone is not completely vapour proof. It's possibly a good idea to put a hole in the back, to keep it dry.