You might want to brush up on OR laws: https://www.oregon.gov/bcd/Documents/brochures/3660.pdfIn Oregon USA the State says they own the water. All of it. Also illegal as far as I know to collect rain water be it for drinking, watering, gardening, farming.
That being said the law kinda gets bent a lot. Especially out in the rural and remote areas of Oregon which are very dry. A thunder storm is not wasted.
You have to know Mexico. It's hard to have a gun if you follow the law, but we're talking about Mexico. You're trying to apply U.S. logic/fears/teachings to a foreign country. Even if a cop busted you, you'd get out of it for $20 or less. If the cop(s) is a hardass, it might take $100, but that's about it. Would you follow the law if that's all you needed to get around it?Hard to stand up to the police if you don't have guns.