This really depends on your tap water; in some places tap water is clean enough to work, but it seems yours is not. If you want something to just set and forget, you’ll probably need to do more localised research. E.g Hardness, turbidity, etc.

One of the defining properties of 0 is that anything multiplied by it results in 0.

So in your operation, without being given the actual result, I’d say no, the question is ill-defined.