If everyone should have access to water, federalize water utilities and don't charge anyone. You will them have to deal with access rights though. How much water is enough for everyone to have access to? How do we avoid water rights issues even worse than what California has?
Defining certain resources as a fundamental right while still forcing them to operate as a free market is a risky game of chicken. If prices are still able to fluctuate in response to market supply & demand then we really aren't saying we truly believe everyone should have water, shelter, etc. A UBI is only an agreement that some amount of money is a fundamental right, nothing more.