New rules as of February restricting bank account holders to long term residents, many banks now require a work permit to open accounts, some require a letter from immigration saying it's for visa purposes and or a certificate of marriage to a Thai national or long term visa
Thailand has filtered and treated water the problem is that lead pipe are still present in some places and boiling will have very little effect on that.
Have a good plan and a solid contract and you're all good. I recommend a good lawyer to help guide you through. Be diligent and know your business and you will be fine