While this applies to water fountains, I feel it’s a good example that also applies to other water-based infrastructure:
Both the pond and the aerator are ineligible, as the pond is meant to retain water to prevent flooding, and the aerator is meant to keep the water flowing to prevent build-up.
Now, you may have seen some water features like this that have Wayspots, but they may have goteen in before there was more clear clarification, or some reviewers still think they are eligible. Not everything that ha a Wayspot is eligible these days, and a good deal do not meet removal criteria, which is more strict than acceptance criteria.
There are some good examples of what is and isn’t eligible in the Criteria Clarification Collection, as well as in the Wayspot Criteria section.