How to prevent floods at home with a stormwater management system

Written by

13 August 2023

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3 min read

Auckland based KPA Plumbing are experts in the design and installation of residential stormwater management systems — a service much needed in the wake of the floods that devastated many areas in the upper North Island.

The afternoon of Friday, January 27, 2023, will be forever etched into the minds of Aucklanders, as the streets, valleys, and homes of many flooded almost instantly. Stormwater management is not a new conversation, but since the devastation of the upper North Island floods, KPA Plumbing director Max Semmons-Russell says the focus has heightened.

“We're now seeing more robust systems being demanded, with a trend towards green infrastructure integration. The rains will come again, and hopefully Auckland has enough time to rebuild infrastructure to cope with the increasingly intensive rainfalls.”

With over 20 years’ experience in public and private drainage, high-end residential plumbing, light commercial, and housing developments, Max founded KPA Plumbing in 2018 in response to Auckland’s growing construction industry. The KPA team is small — the result of Max’s intention to keep things personal — yet, with the support of local contract engineers, the team is able to deliver complete design, planning and installation of plumbing, gas, and stormwater systems.

KPA Plumbing's process includes a thorough site assessment, consideration of local soil and rainfall patterns, and design of an effective, code-compliant system by KPA’s contract engineers.

Every residential property is different, so KPA ensures the stormwater management system is designed to fit.

The state of stormwater management

While there are a number of factors that contribute to the overload of stormwater infrastructure, the reduction of permeable ground cover from land development is a key player. As catchment areas are developed, permeable grass is replaced with impermeable surfaces like concrete, increasing the flow rate and volume of stormwater run-off. Consequently, water that would have once been absorbed into the ground is instead destined for stormwater infrastructure. Unless managed, this change in hydrology puts undue pressure on streams and rivers, accelerating erosion and bank instability.

By installing stormwater management systems that include attenuation/detention tanks, water is temporarily stored and slowly released into the stormwater infrastructure, reducing the load on the system and the risk of localised flooding.

When installing a system for an existing house, the team need to design it around existing infrastructure.

Channel drains are a common solution for existing homes.

Designing and installing residential stormwater systems

As experts in residential stormwater management, KPA Plumbing are often contracted to complete the planning and installation of stormwater drainage systems for both new and existing properties. This process includes a thorough site assessment, consideration of local soil and rainfall patterns, and design of an effective, code-compliant system by KPA’s contract engineers. “Once approved, our team installs and tests the system to ensure peak performance,” Max explains.

Every residential property is different, so KPA designs each system to fit. “We focus on property size and slope, soil type, rainfall data, house layout, and adherence to New Zealand's building codes. For every job, our goal is an effective, integrated stormwater management system.”

The approach is slightly different for new builds and existing properties, Max explains. For new builds, the KPA team is able to design and install a drainage system without having to navigate old buildings and infrastructure — a blank slate with a multitude of opportunities. For existing homes, the solution is often necessary enhancements or a redesign of the current system.

Stormwater management systems can be easily integrated with landscape design.

“We use a range of systems such as Allproof channel drains and sumps, APD detention tanks and package pumps, Dux AdjustaPits, and Davey rainwater filter systems to supply homes with potable drinking water. We also leverage green infrastructure like rain gardens, bioswales, and Promax stormwater tanks for larger properties.”

“To equip existing properties against potential flood threats, we install advanced features like channel drains and cess pits, use permeable pavers, and adjust land grading,” Max says.

Auckland needs to prepare for the likelihood of regular heavy rainfall, and as the Council focusses on strengthening the city infrastructure, homeowners can ensure the protection of their properties, and help reduce water overload, with the installation of effective stormwater management systems.

Learn more about KPA Plumbing.