you would be crazy to drink tap water anywhere in Thailand. Much of the much of the country lacks proper environmental infrastructure such as sewage treatment and garbage pickup. As a result there is a lot of trash on the sides of the roads, on river banks, and on beaches except where they are cleaned up by resorts or other parties. There seems to be very little regulation regarding filling and destroying wetlands.
you always leave out the income verification method for non-O based on retirement, in other words showing 65,000 baht deposits for 3 months from a foreign source into a Thai bank account. And sometimes when you were first apply they only want to see 2 months.