Thanks. Sorry, there's a misunderstanding CraigYoung - I'm talking about overnighting on the dock at BILBAO on the way home. Yes we have a CL nearby for the trip out from Portsmouth.
Yes Jaydug - no problem in carrying water with us (don't need much for 16 hours on the dock anyway).
It's just that the car and van are loaded to capacity with all the stuff for 10 weeks in Portugal, plus the excellent wine we want to take home, so every kilo I can save is worth-while.
No problem and thanks for the responses.