When flying, I normally take an empty water bottle (or two) with me. To comply with liquid regulations at security, I ditch any remaining water landside just before or after checkin, pass through security with completely empty water bottles (which is allowed), then find a water fountain air-side to refill it. I then have (for free!) water for the flight.
I can't see anything on the London City Airport website, either in text or on the map, about water fountains. I couldn't spot any either from a quick look in person, but I know that while London's Heathrow Airport has them they're not always the easiest to spot without directions, so it isn't impossible I missed them.
So, are there drinking water fountains air-side at London City Airport, and if so, where?