You have a contract for the condo not the building. Unless there's a " no noise" clause (extremely unlikely) you have nothing to stand on. Not sure why you think "he lied", if your referring to the person you rented from, he got the answer from the building.
To presume there will be no noise from outside the condo is unfortunate and foolish. There will always be noise from some common area or neighbor in every condo. Don't expect the building to make any adjustments in the pump operation although you can ask. The pump serves the building so its impact on whatever it serves will most likely outweigh your issue.