Mernda facts for plumbing
Sewer since 2010
Whittlesea's 2018 wastewater plan says Mernda was connected through the sewer backlog program in 2010 and the majority of those properties are on sewer.
Septic elsewhere in the city
The same plan counts about 1,300 domestic septic systems in the City of Whittlesea. Unsewered land sits in small pockets of Thomastown, Epping and South Morang, in rural districts further north and around Whittlesea Township.
Mortgaged households
At the 2021 Census, 55.1% of homes in the suburb of Mernda were mortgaged, against 36.1% across Victoria, and 89.4% were separate houses.
Water hardness
Mernda is in Yarra Valley Water's Epping sampling area, which averaged 30 mg/L of hardness in 2025-26, ranging from 26 to 34. The guideline is 200 mg/L.
If your block still has a septic tank
Whittlesea says a property without access to the town sewer must treat and contain its household wastewater in a septic tank system. Installing or altering one needs a septic tank permit from Council.
Council's upkeep advice: de-sludge the tank every three years, keep oils, grease, food scraps, paints and medicines out of it, and never drive or park over any part of the system. Our septic systems page explains what a plumber checks.
Sewer drains and new work
Yarra Valley Water runs Mernda's sewer. A blockage in your own pipes is yours to have cleared by a licensed plumber, and Yarra Valley Water doesn't reimburse internal pipe repairs. Its responsibility near your property depends on the site, so ask it before anyone digs near the boundary.
Building? From 1 January 2027, all new homes in Victoria will be built all electric, so check current rules with your builder before planning gas. For other jobs, see blocked drains in Melbourne, a blocked toilet, CCTV drain inspection or heat pump hot water.
What we would do
If you've bought in Mernda and aren't sure the house is on sewer, find out before you renovate a bathroom or add a toilet. Ask Yarra Valley Water whether the property is connected, and look for a septic tank lid or a sewer inspection opening in the yard. A plumber can then plan new fixtures for the system you actually have.