Wellingtonians value our local environment immensely. We are the city of bush, sea and fresh air. Our citizens are ecologically conscious.

So why do we find ourselves with polluted beaches and streams resulting from failing water infrastructure?

The evidence of our crumbling waste, storm and drinking water network has been dramatically exposed in recent months: More than five million litres of wastewater dumped in our harbour, polluting the sea, preventing swimming and threatening marine life. Truck-load after truck-load of waste-sludge being driven to treatment facilities due to failed sewer pipes. Local businesses severely disrupted. Millions of litres of water "leaking" from our pipes. Dozens of homes being cut-off from mains water, boxes of emergency water supplies stacked outside their gates. A refusal to sign-post the polluted Karori Stream. Ongoing offensive discharges in Houghton Bay and a "tsunami of faecal matter" in Owhiro Bay.

How has this pattern of failure occurred in a developed, relatively wealthy and environmentally aware city? Have we been so focused on pollution in our rural areas that we've missed the rot beneath our own feet? Have our local councillors eschewed investment in pipes in favour of sexier ribbon-cutting opportunities?

The easy thing to do is to blame Wellington Water, the entity charged with managing water infrastructure on behalf of local councils across our region. That's a mistake. Yes, it should do a much better job of communicating about these issues and no doubt it's imperfect. Ultimately though it's only as good as the councils who govern and fund it. They set the performance expectations. They set the funding envelope. They are ultimately responsible.

The warning signs are all there in Wellington Water's latest annual report: deferrals in its capital works programme, unconsented discharge, targets not achieved, projects delayed, a 'baseline' of 43 overflows of wastewater into public places each month. Elsewhere, Water NZ has reported that Wellington's wastewater system is in the worst condition of all major New Zealand centres - with around a third of our wastewater pipes in poor or very poor condition.

Councils are now fronting-up to the challenge. Good. My plea to them is not to get distracted by the politics of finger-pointing, shuffling of deck-chairs or laments for past inaction.

Our shared focus must be on getting this right for the future.

Each council owes us a transparent assessment of the true extent of our water infrastructure deficit, the environmental risks it poses and a concrete, costed plan for addressing it. We need that information now and at regular intervals into the future. Here are some basic questions we all deserve answers to:

• Which local streams and beaches are polluted by contaminated discharges? How often are they tested, are communities properly informed, what's the plan to fix that pollution and how is it progressing?
• Which pipes and connections are at risk of failure with major environmental consequences? When will they be fixed?
• Is our pipe maintenance and replacement programme advancing in line with global best practice?
• What water losses are occurring and when will they be fixed?
• What are we doing to future-proof our water infrastructure and to prepare for population growth?

The ultimate question is: how much will it cost to improve our water infrastructure to meet the high environmental standards Wellingtonians expect? The numbers may be eye-watering but it's simply not sustainable to look the other way. We can't even begin a conversation about how we fund it all, what trade-offs may be required or what role central Government may need to play until we know how bad it really is.

I've had some city councillors suggest I should stay out of this issue. I reject that entirely. I want my kids to be able to play in Karori stream or swim in our harbour without facing major health risks. I want yours to be able to as well. I want all our local leaders to give these challenges the energy and urgency the environmental threat demands.

A cleaner world starts in our backyard.