I spent the morning at a residential house in Boroondara (eastern suburbs of Melbourne), talking about the potential to create the most water sensitive house in Melbourne (big call I know!).
Already the owner has a 26,000 litre tank that captures runoff from the entire house, a greywater system, an bund to capture overland flows, and an irrigation system across the whole site (but not always in operation).
We spent some time going through how to maximise every single drop of rainfall, reduce overland flows, increase infiltration, increase evapotranspiration, support the veggie patch, plant more natives and fruit trees, and the creation of a new ephemeral wetland.
We mapped out a plan for:
A new leaky tank drip fed line from the 26,000 litre tank
Ephemeral wetland fed from overflow
Adjusted sump pump to extract more water from pit that collects all roof runoff
Reconfigure of greywater to act as a back up for tank water
Reconfigure of greywater to add a natural filter bed at source prior to gravity fed irrigation
Two new infiltration trenches
One new raingarden for overflow from stormwater pit
A maintenance regime
The stormwater on this property will then virtually never leave via a pipe!
What I think is interesting is that we were able to identify some small but very significant issues to improve the performance of this household system. For example the stormwater sump that was collecting all runoff from the house and pumping to the tank, had a lot of standing water due to the location of the float. I think we could harvest 25% more water just by adjusting this float.
What I found particularly inspiring is that this whole project wasn’t driven by any compliance or requirement to meet planning controls. Just a passionate and energetic home owner doing their bit!
Will hope to revisit during construction and verify this is on track to be the most water sensitive house :)