Ok, I can't believe I never coped this until now, but you don't have to join the end bit back to the start. This is why I couldn't get very high scores !! You can just keep going off in whatever direction you want. I kept trying to join back up at the start, but it doesn't matter. Logically though this would mean the "water" would run out of the last pipe that's not joined up, but for this game, that doesn't seem to matter!!
Also, if you cross sections you get bonus points.
