Forget about 'asking' anyone anything directly when it comes to the integrity of the house. The sellers can say no or yes but should it come to push and shove, it's he-said-she-said. Not all states have mandated disclosure, one of which is my state of PA. However, by Fall, it's been predicted to become law.
It's not my experience that just because a seller says 'no' to water leakage that it can't be proven that they didn't know about it. I happen to know 2 engineers that have taken on cases where even chalking was used as proof that the seller had to know about water in the basement, no matter how little. The engineers only had to prove the past existance of measureable water in the basement; not that there was 'flooding' by its definition. There are other factors that they use to show preponderence of the evidence to make their case, like negative slope, joint separation, leaking gutters/downspouts during a rain (no matter how slight), water lines on the wall, water lines on the HWH or HVAC units, and so on. Granted, if there aren't many signs of past water in a room, one won't have a case. But the 'experts' tell me that they can usually find sufficient evidence. And certainly, cobwebs in the sump pump isn't evidence in one's favor of proving water in a basement.
It may cost more to make the case then it's worth to just fix the problem, and the engineers usually say this is the case 75-90% of the time. When a homeowner finds out that they get water 6 mo. later, the engineers have said, "Yeah, we can make a case for $6000 but it will only cost $3000 to fix the problem." (Since the engineers don't get many cases to court, they charge a fair amount of $$$ for what few cases they DO get to court.) See ya on the Forum.