Simon, Its obvious this debate is based on the assumption he is stealing the water.
Ever since we purchased our house a couple of years ago, I've suspected that our neighbour was using our tap to water his gardens. The water bills always seemed a lot higher than what we had used. So much so, I've purchased a lockable tap, but haven't installed it yet.
Last night I think I finally caught him. But you didn't actually see him right??
Making assumptions of guilt based on this is pretty wild to me. So whilst I would certainly suspect someone I wouldn't be sure. What if it was the next neighbour along? Pretty smart to run his hose across to the second block along - he is not even considered a suspect at this stage.
So install your lockable tap - just will take a minute or two and all is done.
You got to live with this guy living next door, anything you do to confront and accuse him will only make things worse. Life is to short to be getting around creating bad blood between people.
Easy way out is to install your lockable tap. His days of easy water are finished, he will know you are onto the water theft and he would be pretty bold to try to defeat the lock and then be like most Australians and ignore him from now on.
If he does try to circumvent the lock just call the police. I suspect a damaged lock will be some form of breaking and entering.
Why escalate things? What if the guy has a mental illness? A lot of us do! You could really end up with an unpleasant situation which is way worse than a suspicion and an uneasy over the fence relationship.
I just like to live my life striving for happiness and trying to help other people be happy. Being on the offensive is just all too hard and will more than likely come back on you. I would seriously look at myself in this situation and do what I could to create a better relationship with my neighbour. He would only steal from you cos he doesn't see you as someone he particularly likes. That would be the gap I would want to fill - what sort of person steals from a mate? I am not trying to be holier than thou - I would genuinely do this and in my experience it works. What you do will always come back to you in one way or another.
Or just form a Somersoft vigilante group and teach this guy a lesson he will never forget. He won't be going around stealing people's water after you guys are done with him. Probably start with breaking his fingers so every time he uses a tap from then on will remind him of the time he crossed the Somersoft Water Citizen's Action Group.
I hope I haven't offended the more precipitous of us - don't want a beating myself .....