Here's how this works. The state will try with every ounce of its power to seize control of as much of your income and your rights as it can. That's the basic rule of all state activity.
The scam is always some variant of what we see here. A worthy cause that needs to be supported or a public problem that should be addressed. This works best if there is some legitimacy to the need or problem, and it works even better if those affected can be characterized as poor, non white or in any way disadvantaged.
Instead of using the money sources they already have to address the issue, the state whines that it needs, usually desperately, new revenue streams through taxation to allow the state access to the money it needs to make it all better.
At first glance, sounds good and right to most people.
But, it's that old camel nose under the tent. Even if the tax allowed is initially low, or "negligible" as is argued in this instance, it will never stay that way. There will always be a new problem that now needs to urgently be addressed by our betters in government, and that will require the tax to go up.
And go up it will, until the state is seizing as much money from your water bill as it can possibly get away with.
Will the state solve the original problem? Maybe, but probably not, as that problem is the justification for the tax, and if they make that problem go away, then someone might start in on lowering or even eliminating their income stream.
In short, never let the state get the chance to grab more of your money, for any reason. Isn't the current regime of income, property, sales and gas tax enough? Aren't the multitude of fees, charges, registration levies , and general charges for every government service enough? What's next, a tax on the air you breathe?