if it is an old house with cast iron drain the Y tie junction may become corroded and just start to leak when there is significan pressure when the toilet is flushed.
HOA could be responsible if the drain pipe is shared by mult
multiple units. In your case, you and downstairs are sharing at least. Your next-wall neighbor maybe sharing it as well. Talk to HOA (or the hired managment comany) and they may already have policy dealing with this. In most cases, inside the wall could belong the community since they are shared.
I contacted my home insurance and was told if I filed a claim, my insurance would initiate the investigation/inspection, but even if finally it's my neighbor or HOA insurance pay for the repairment, there will be a record that I filed a claim.
二层condo, 楼上厕所冲马桶时，楼下邻居厕所马桶后面的墙角（开了小洞）可以看到墙内突然有一两秒钟的哗哗流水！有点像是水杯倒满后一下子溢出的那样。楼下厕所后面的墙是潮湿的，楼下用手一捅就开了亇小洞。楼上不冲马桶，楼下也就没有流/漏水。
从流水量上看，绝大部分"黑"水应该还是从下水管道冲走了，只有最后相对很少一部分的"白"水冲出了下水管流到楼下墙里。
楼下的天花板（楼上马桶位置）是干的，也沒有一点水迹。
请教这事要从哪里开始处理，是楼上的保险还是楼下应该负责，还是HOA的保险？会不会是墙内下水管道的拐弯处密封不好破裂引起的？请教各位，先谢谢了！据广告自称是节水型的，看起来冲力是比老式马桶要强些
if it is an old house with cast iron drain the Y tie junction may become corroded and just start to leak when there is significan pressure when the toilet is flushed.
谢谢！
multiple units. In your case, you and downstairs are sharing at least. Your next-wall neighbor maybe sharing it as well. Talk to HOA (or the hired managment comany) and they may already have policy dealing with this. In most cases, inside the wall could belong the community since they are shared.
I contacted my home insurance and was told if I filed a claim, my insurance would initiate the investigation/inspection, but even if finally it's my neighbor or HOA insurance pay for the repairment, there will be a record that I filed a claim.