Riverstone at a glance
Valley flooding
NSW SES says floodwater flows into the Hawkesbury-Nepean Valley more quickly than it can flow out, so it backs up. Around Riverstone, flooding can also come from the Eastern Creek catchment.
How many homes
SES says a repeat of the 1961 flood, about a 1 in 30 chance per year, would flood around 60 Riverstone homes. A 1 in 500 chance per year flood, like the 1867 record, would affect over 400 homes in the area.
Houses, many on a mortgage
At the 2021 Census, 94.5% of the suburb's occupied homes were separate houses and 1.0% flats. 44.0% were owned with a mortgage, against 32.5% across NSW.
One council
Riverstone lies wholly in the Blacktown council area. Blacktown City Council issues flood advice letters for individual homes and approves on-site sewage systems.
Rain, floods and the sewer
Sydney Water says that when stormwater gets into its wastewater pipes, they overload and overflow onto properties, sometimes inside homes. The usual ways in are downpipes wrongly connected to the sewer, cracked private pipes that let groundwater seep in, and damaged or low-lying overflow relief gullies.
That gully near your outside tap should act like a safety valve, keeping stormwater out of your wastewater pipes. If yours is cracked or sits at ground level, ask a drainer to raise or repair it before the next wet season.
Septic systems in Blacktown City
Blacktown City Council says some un-sewered communities remain in the City's rural areas. It doesn't name suburbs, so ask Council if you aren't sure what your property has.
Where there is an on-site system, installing or operating it needs Council approval under section 68 of the Local Government Act 1993. Booking maintenance is the owner's job, and Council says an authorised Environmental Health Officer should inspect the system every 1 to 3 years. Our septic systems page explains what a plumber checks.
Your pipe or Sydney Water's?
Sydney Water treats wastewater at its own Riverstone plant, which discharges to South Creek via Eastern Creek. On a sewered block, your private pipes run out to the junction on Sydney Water's main. You own them up to and including that connection point, even where they cross the boundary. For a blockage, start with blocked drains in Sydney.
What we would do
Get Blacktown's flood advice letter before spending on new drainage, a ground-level hot water unit or a granny flat bathroom. It gives detailed flood information for your address, and a plumber can use it to decide where fixtures and gullies should go. Then have the gully and downpipe connections checked, since Sydney Water names both among the commonest ways rain gets into the sewer. We'll match you with a drainage specialist for the work.