Tahiti’s heat and humidity hasn’t affected you Jimmy, because for what it’s worth I agree with you to the extent that if any changes on common property or lots affects the overland flow path of the property’s stormwater or the effectiveness of its inter-lot stormwater drainage, then all runoff should be collected and re-directed to the site’s stormwater system.
chesswood‘s first remedy must be to formally raise the issues with the Owners Corporation, and if that doesn’t (or hasn’t) achieve the desired outcome then an approach to Council can’t hurt, because as a minimum they may lean on the O/C and the neighbour to address the stormwater problem.
I’m becoming even more disillusioned with the effectiveness of the traditional means to resolve strata-related disputes in NSW (i.e mediation by Dept. Fair Trading and where necessary adjudication by the NSW Civil and Administrative Tribunal), and so I’ve again confirmed with the NSW Dept. of Justice that it’s Community Justice Program is still able to assist with mediation component of the process despite Service NSW instinctively directing inquiries to Fair Trading.