At trivia events, I have asked a question that often has locals stumped: "Campbelltown shares a border with Camden, Wollondilly, Liverpool...and which other local government area?"
It results in wild guesses - Wollongong perhaps? - but the correct answer is Sutherland Shire.
Campbelltown adjoins ScoMo Land - but it's out in the water catchment zone, the border going through the middle of Woronora Dam.
So, given our local rainfall technically flows into that dam, is that where we get our drinking water from? No. Water from Woronora (which sits at 39 per cent full) goes to Sutherland Shire homes.
Some think our tap water comes from Warragamba Dam (now at 51 per cent) but, no, it supplies Sydney. Wollongong gets water from Avon Dam (at 49 per cent).
Most of Macarthur gets its drinking water from Cataract Dam, near Appin. Which is at just 28 per cent - and sliding. Not good.
Particularly because it's a stand-alone dam relying solely on rainfall, unlike other dams where water can be pumped from one to the other. If it runs dry we can't just flick a switch to get more.
Which is why locals are worried, particularly as more and more housing estates are rammed through.
I touched on this topic a while ago, as have pollies such as Greg Warren and Judy Hannan, but the government has refused to bring in added water restrictions as the local level gets lower.
"The big challenge for us is that Warragamba Dam skews the statistics for the whole of Sydney due to its size," said Wollondilly deputy mayor Matt Gould. "But we cannot access water from Warragamba or the desalination plant."
When that quote appeared online last week, the critics assured him that WaterNSW surely had it all under control and would bring in restrictions if needed. Surely.
But Sharon Robinson of Dilly Drought Drive pointed out that WaterNSW doesn't make that decision - the government does.
We have no idea what the latest expert advice to the Minister is, re Cataract Dam, but I do get nervous because WaterNSW has been ignored in the past by politicians who think they know better.
A classic example is when the water experts opposed the madness of mining under Sydney's catchment...but the government approved it anyway. Mining companies, like developers, are VIPs.
The result is (of course) cracked creek beds, water loss, bubbling methane gas vents which flame up, iron oxides and other chemicals leaching from fractured rock.
This is our government doing this to our precious water supply - not terrorists.
Sharyn Cullis of the Georges River Environmental Alliance was shocked this year to obtain correspondence that showed WaterNSW was almost begging the NSW Planning Department to consult with it re the massive local housing estates. "[That] indicates those discussions haven't yet occurred!" Sharyn marvelled to this paper.
I wouldn't have thought that level of incompetence possible...but this the same government that had a full decade's warning Oran Park needed a school for its young families...but still ended up in panic, supplying rows and rows of demountables.
I have faith in WaterNSW and Sydney Water - but not the pollies calling the shots.
And, re the big question Wollondilly mayor Matthew Deeth asked last week: "How much population growth [in Macarthur] can our water supply withstand?"
My fear is the government doesn't know. Even worse... I fear our government hasn't even asked the question.
WaterNSW has been ignored in the past by our politicians.