16d)Might also be Watermeter.
By the way, in the edition of the Guide that I purchased the clue for 1d) is not printed. The correct answer appears to be "undercover".
in 16d are the lines shown before the H20- exactly as set out by poorclare.
I am not sure of the reasoning behind water meter. Water water looks okay. (If the dashes were after the h20 H20 I wondered if it could be Everywhere but that's 10 not 5,5)