WWII bunkers in the Aberdeen Reservoir area [????- ]

The marker above is just an approximate location.  My GPS logger reading for this is Lat 22.259720N Long 114.163607E  Don't know whether there are tunnels linking this one with the other ones nearby.  There is also a concrete water tank at the opposite side of the road.  Don't know whether it has anything to do with the bunkers nearby.

A peep into the opening between the bunkers:

Don't know if this water tank has anything to do with the bunkers.