A: They’re largely the same thing. Ongoing/running costs mainly come from energy use, so there is also an emissions ‘cost’ to this.

A: Innovation increasingly helps water companies operate more sustainably/efficiently. Maintenance is also an ongoing cost.

A: It depends on whether the tank is plumbed in, and how big it is. If it’s small, it’s cheaper, but also less useful in summer. If well maintained, rain tanks can last up to 20 years.

A: As a large-scale option, costs are high for rain tanks because so many are needed in total to get relatively less water. (compared to large infrastructure options that we all share the cost of in our water bill).

A: This will be a function of the quality of the tank itself, the environment it’s used in (submerged in soil, above ground etc) and maintenance etc. Many polyethylene rain tanks have a 20-25yr warranty.

A: Water efficiency includes some big costs like renewing pipes (digging up streets, traffic management, resealing the road), installing smart meters, campaigns for behaviour change, greywater systems (need to involve plumbers).

A: The actual cost would depend on the scale of the solution. It would be higher than one large infrastructure option because we would not get the economies of scale from many micro-solutions. If it were a larger option, it would require a second network of pipes.

A: Desalination is about the same cost to build as option 5 (indirect recycled water for drinking) but more expensive to maintain.

A: Money only comes from bill payers. The cost to the public is the cost of building and operating these options spread over the whole population of bill payers.

A: There are no plans in place for this. If it happened, it would be paid for by Auckland billpayers (a redistribution of income, likely to be from people without gardens to people with gardens)