"Freeloading off a public good"? You need to decide if your imaginary strawman
Certain states, such as Colorado, have handed out fines in the past to those who have a water barrel to collect rain water. Such laws were under the belief of water theft, where the rain that lands wherever would always reach a river or natural water basin, and that diverting it for personal use is theft of the resource that was provided by God(tm) and the State(tm).
So before you fling around words such as "imaginary", at least check to make sure that it isn't an issue. You'll note that this is a daunting task, because there are at least 50 states in the US, all of which have different laws concerning water harvesting.
Oh, and those issues shouldn't exist in the first place, rather than having a fix being demanded.
is a conservative or Leftist here.
Once you break out of binary thinking, you can find a group that is in the middle of the horseshoe. Namely, the group that dislikes premitting large scale collection while prohibiting individuals collecting rainwater on a small scale.