With the bylaw up for review, the council was taking the opportunity to promote sustainable development practices that emphasised environmental quality and would reduce growing pressure on ageing infrastructure, said the council’s regulatory and planning general manager Dr Ian Davidson-Watts.
The proposed changes were part of a larger Water Taskforce Action Plan being rolled out this summer by the council to tackle the issues and challenges around water supply and usage.
The council appreciated last summer was tough for residents, given the water restrictions and supply issues, Dr Davidson-Watts said.
"Climate change predictions point to longer dry periods but heavier rainfall events. This means we need to be proactive and look at long term sustainability to ensure the impact on urban residents is minimised."
Making the installation of rainwater tanks compulsory for new residential, industrial and commercial builds would relieve some of the pressure on urban water supplies.
It will also help reduce the impact of heavy rainfall on stormwater networks.
Planning consultant Keith Hovell said the proposed minimum tank size was 3000 litres, and that the rainwater would only be used outdoors and was not intended as a potable water source.
"When the tank is full it will provide enough water for almost four hours of hosing."
"Rainwater capture will reduce residents’ reliance on treated water for use outdoors, which means less demand on our water supply."
The other significant change to the bylaw was encouraging green infrastructure, such as rain gardens and grasses, for new builds in Gore, Mataura and Waikaka.
This was aimed at reducing the amount of water that floods urban stormwater networks during heavy rainfall events, Mr Hovell said. In the past little consideration was given to providing permeable areas to reduce runoff from sites, and the use of concrete or compacted gravel was the norm.
"Again, given climate change predictions that there will be more intense rainfall events, we need to change the way we do things."
Dr Davidson-Watts said it was common knowledge Gore and Mataura had an ageing stormwater network that would cost millions of dollars to upgrade.
"Green infrastructure filters the water, is resilient, visually pleasing and contributes to biodiversity.
"It also provides savings and benefits to ratepayers."
As rainwater tanks and green infrastructure would not be practical all the time, the draft bylaw allowed requests for dispensation.
Dr Davidson-Watts stressed the draft bylaw was only for new builds. However, the council realised there was likely to be a lot of community interest in the proposed changes, particularly rainwater tanks.
"As part of our task force action plan we will be considering options for existing property owners."
The draft bylaw will go to the council’s meeting on October 30 for adoption and is scheduled to be released for public consultation early next month.
"The plan is to have feedback in by early December and look at a hearing, if one is required, in the new year."
