The seller is required by law to disclose any leakage in the basement (even if it's a small amount.) ...and especially if you ask them directly (or the real estate agent) if there is any leakage in the basement. If they tell you that 'it has been their experience' that there is no leakage, then, although not 100% airtight (or watertight) you can sue them for the cost of the repair if you find out that they misrepresented the house.
However, if they just haven't noticed the problem and you can't prove that they knew about it (although if the problem is serious, neglecting what goes on in the basement is not a plausible defense) then you have no recourse. But saying they never noticed that two gallons of water come into the house during every rainstorm would not 'hold water.', haha.