My raingarden diary features in the latest issue of ReNew Magazine. Ironically, this issue (No. 135) is subtitled ‘The Water Saving Special”, while the biggest challenge for our system is to use enough of the large volume of water that our house produces.
Even with the gardens growing amazingly over summer, the water they have used since the start of this drier- and warmer-than-average year hasn’t been enough to keep the tank from overflowing. The increased summer thirst of the gardens has increased our background use of captured roof water from ~100 to ~115 litres per day. In the 100 days since 1 January, our roof has produced 12,945 litres of runoff, and we (and the raingardens) have used 11,500 litres (about 89% of all runoff).
But the system overflowed at the end of January when we received ~24 mm over 3 days (about 9 mm of this flowed out to the street and to the river). The system could have captured all of this (and protected the river) if we used ~10-15 litres more water each day. I’m hoping that the grape and passionfruit vines will grow enough next year to increase our summer usage by about this much. With similar (low) rainfall, the gardens will have plenty of water to keep thriving, while providing that much more protection to the Yarra down the road.
So, yes, we are saving (mains) water with our harvesting system, but saving our local river means our gardens need to use as much (roof) water as possible. It certainly is a strange, counter-intuitive message I find myself shouting from the rooftops.
Thanks for the post Chris. We are experiencing similar results to you but our house is totally supplied by rainwater – so our rainwater supply is 250 – 300 litres/day with overflows during low rainfall. As you know I have been shouting this same “counter-intuitive” message for more than a decade. Enjoying the detailed nature of your commentary and insights – keep up the good work. Our results are posted on https://urbanwatercyclesolutions.com.