Moderates may favor a sliding price scale to encourage industry, with subsidies so the poor will have good free water to drink. Communists might support decisions by committees of citizens to decide water policy or select representatives to decide for everyone. Conservatives would favor control by local government, and so on. Each believes they know the right price or they know how to find the right price for water. A libertarian will tell you the market will decide.
Market prices are whatever buyers and sellers agree on.
Libertarians not only don't know the right price for water, they believe there's no such thing as the right price for water. Wherever water sells someone else can sell at a different price and be just as right. What makes us different is that we know we don't know. Think about this for a moment. We could say the democrats don't know what's best but the republicans say that.