hello; A pond is a low point and the high surfaces around it can feed water into it. Much will depend on the surfaces. If rain washes across a driiveway, then oils and stuff from autos can be flushed into the pond.
The point about a septic system is worth considering. In the old days it was smart to dig a well on higher ground than the outhouse.
Good luck
all my tanks get water from roof fun offs from the rain. That is how they were designed to reduce the cost of water. No issues. As said before I guess it depends on the pollution levels of the environment.