From a solely visual perspective: As a visual option it is pretty cool, the one downside visually, is that it's surprisingly difficult to differentiate polluted water from grass at night. I would suggest making the water tinting toggleable in game settings.
From a gameplay perspective I think it has some potential; if it was a mechanic. (bare with me)
- Polluted water would increase the pollution created by Power Turbines, because it's Polluted Steam, thereby requiring the creation/use of water filtering, to counteract this.
- Using Polluted water could decrease the productivity of Assembers/Refineries/Chemical Plants that have water in the recipe. (These factories have inherent filtering, but a dedicated filter on the line would be more efficient and eliminate the debuff.
- You could also have polluted water killing the fish in a given pond.
