Dingbatt:
To get back to the OP (rather than slagging local body incompetence), I was surprised at the figure of 40l for a hand wash (the equivalent of 25 1.5l bottles), but I guess by the time you take rinsing into account it would get up there.
Given that our kitchen sink is 900mm long I can well believe that the dishwasher uses significantly less water.
Could always buy a plastic washing up bowl but using the dishwasher means I haven't had to do it by hand. So that's a win all round in my books!