I would suggest that you measure from the water inlet on your caravan to the middle of the rear of the caravan and then add about 2 metres. Many fully serviced pitches have the water connection at the rear of the pitch and about a meter away from the end of the pitch. We carry an extension hose with us as on many fully serviced pitches the standard length is not enough.Thanks everyone, and going by the majority of comments, I think the Aquaroll Mains Adaptor sounds like the best idea to me. There are 7.5 metre lengths advertised, so that would probably be more than sufficient. We always prefer a serviced pitch, so it would be good not to have to keep manually topping up the aquaroll.