Permeable Paving Is One Layer of the Solution

Permeable paving lets rain drain straight through the surface, so the driveway stays puddle-free and runoff never has to reach the council network.

Every square metre of driveway, carpark, or paved yard is a square metre of land that used to soak up rain and now doesn't. As NZ sites get denser and rainfall gets heavier, all that hard surface has become a stormwater problem councils are no longer willing to let go. Permeable paving is one of the few solutions that fixes the problem at the source: it lets water soak through the surface and into the ground below.

For developers, architects, and property owners facing stormwater consent conditions, that makes permeable paving less of a landscaping choice and more of a compliance tool.

What Is Permeable Paving?

Permeable paving is a hard-wearing surface engineered to let rainwater drain straight through it into the ground or a storage layer below, rather than shedding it to a pipe or the street. It carries  the load of conventional paving but behaves like open ground by hydrologically cutting the volume and speed of runoff a site generates.

That distinction matters because runoff is exactly what NZ's stormwater rules are trying to control.

Why Runoff Is Under Scrutiny

Traditional impervious surfaces send rainwater somewhere else, fast. On a single property that seems harmless. Across a catchment of driveways, roads, and carparks, it overwhelms stormwater networks that were sized for a less paved, less intense-rainfall era.

The Auckland Anniversary floods of January 2023 caused over $13 billion in damage nationwide and turned stormwater from a background concern into a design priority. Since then, councils have tightened how much runoff a development is allowed to discharge, and enforcement has sharpened.

In Auckland, the Stormwater Management Area Flow (SMAF) controls require many new developments to manage runoff on-site rather than pushing peak flows onto the council network. Other councils have adopted similar frameworks. The practical result is that reducing impervious area, or offsetting it, is now a consent condition on a lot of projects.

Where Permeable Paving Fits

Permeable paving earns its place by doing two jobs at once: a usable surface and a runoff-reduction measure. It suits the parts of a site that would otherwise be dead impervious area:

- Driveways and access ways on residential and lifestyle properties

- Carparks for commercial, retail, and community sites

- Overflow and hardstand areas that need to bear load without shedding water

- Paved urban and pedestrian areas where surface water pooling is a problem

Porous Lane is WaterSmart's permeable paving, engineered for New Zealand conditions. It carries vehicle loads like conventional paving while reducing runoff and increasing the permeability a site can demonstrate at consent.

Permeable Paving Is Part of the Toolkit, Not the Whole Answer

Reducing runoff at the surface is the first move. Many sites also need to hold and release water at a controlled rate, and that is a different job.

On tight or high-density sites, Aquacomb provides stormwater detention in-slab, storing water beneath a driveway or building where there is no room for a separate tank. For sites needing larger underground volume across varied soil and water-table conditions, StormVAULT handles the storage end.

The right combination depends on the site. A residential driveway might be solved with permeable paving alone. A commercial development with a large roof and carpark often pairs permeable surfaces with detention storage to meet its flow-rate target. The point is to match the measure to the site's actual runoff obligation, using each product for the job it does best.

What to Plan For

A few things keep permeable paving working as intended and easy to maintain:

Get the council's flow-rate requirement confirmed early. SMAF thresholds and zone-specific rules vary. Knowing the target before the design is locked in avoids expensive rework at consent stage.

Design the sub-base for the load and the soil. Permeable surfaces rely on the layers beneath them to store and release water. Ground conditions, expected foot or vehicle traffic, and the design storm all shape that build-up.

Plan for maintenance. Permeable surfaces stay effective when sediment is kept from clogging the voids. Periodic cleaning keeps infiltration rates where they need to be, and it belongs in the handover, not as an afterthought.

Treat it as a design decision from the outset. Permeable paving specified early can offset impervious areas and reclaim usable spaces . Retrofitted late, it becomes a patch on a problem that was already consented around.

FAQ

Does permeable paving meet stormwater consent requirements in NZ?

It can form a core part of a compliant design by reducing the runoff a site generates. Whether it satisfies consent on its own depends on the council's flow-rate target and the site's impervious area. On larger sites it is often combined with detention storage to meet the required discharge rate.

Is permeable paving strong enough for driveways and carparks?

Yes. It is engineered as a trafficable surface for vehicle loads, which is why it suits driveways, carparks, and hardstand areas rather than only pedestrian zones.

How is permeable paving different from a detention tank?

Permeable paving reduces runoff at the surface by letting water infiltrate. A detention system such as Aquacomb or StormVAULT stores captured water and releases it slowly. Many sites use both: the paving cuts the volume, the tank controls the release rate. In some cases (e.g. when expansive clay soils are present), permeable paving can be designed with a storage layer and a perforated drainage pipe that slows down runoff discharge to the main stormwater network.

Does it need much maintenance?

Periodic cleaning to clear sediment from the surface  keeps infiltration rates up. Built into a normal maintenance schedule, it is straightforward. 

Getting It Right for Your Site

Stormwater rules in NZ keep tightening. Permeable paving is one of the clearest ways to turn a site's hard surfaces from a runoff liability into part of the compliance solution, and it works best when it is planned in from the start alongside the right detention measures for the site.

WaterSmart works with developers, architects, and property owners across New Zealand to specify permeable paving and stormwater systems that fit the site's real conditions and consent requirements. Talk to the team about your project.