刚做完local search,说property boundary有个public sewer,这个是不是问题呢？

这个是正常的，只要畅通无阻，就没问题。

in other word, if it's blocked in the future, your home will be the first to be flooded... i think it's something you can get the price down a little bit

how little?1,000? 5,000??
The owner said it never had problem before??

个人认为，这个不能当作砍价的筹码，因为房子就是这样设计的，而且目前也没有问题，如果卖主不答应，你也没办法。除非你说那你就不买他的房子了。

俺们滴survey结果出来，说自家滴下水道有些小堵，但不是urgent要处理的，LG说问问卖主能不能给fix, 但是如果卖主说no, 俺们也只有自己日后找人fix，因为不能为了这１，２百胖白费了那些时间，精力和律师费。

关键是在public sewer上面,不能再建建筑物了吧?

it's not connected, but normally it shouldnot put heavy stuff above public sewer in case of a blocked drain, let alone a building.

I guess A LITTLE BIT means A LITTLE BIT, it's very much depended on your negociating skill and how much you want the house. Public sewer's the responsibilty of the utility company instead of individual, but your home insurance could go up a bit coz of flooding hazard, you can probably use that for the reason of bargain.

Of course the situ's not in your favor coz you have paid survey and/or legal fee. The vendor knows it's fat chance you will withdraw on the ground of petty thing.