After heavy rains, especially if they are the first decent rain in a while, it is always a good idea to stay out of the water for 2-3 days.

Some good info of current readings / water quality reports can be found here...

http://www.environment.nsw.gov.au/beach/Reportbulletin.htm
www.environment.nsw.gov.au/beachapp/BotanyBulletin.aspx

Then again when the conditions are "on" just pretend the brown water is chocolate milk and go for it, but be honest with your doctor afterwards so they can prescribe the right amount of ear bashing and drugs

I'd love to see you kiting through the sewerage system. They must be putting in some massive pipes and fans to help you do that.
I think you mean sewage.

shhhhiiiiiitttt!