Constant bumping noise
This might very well be water hammer, where liquid alternates gas it will 'hammer' into any curves and can make noise. Have you tried turning of all powered devices by just flipping the main switch? Does it still make noise then? Try to eliminate all possible sources one by one. It might just be a faulty bearing in one of the pumps. Are there any other constructions near the building where the noise could come from?

This is not really an answer, but you didn't really ask a question either. If I was able to comment on this SE, this would have been a comment.