When Should You Use a Retention Tank?

Understanding the role of retention tanks in smart water management.

As sustainable development becomes increasingly important, managing how water is collected, stored, and reused on-site is more than just good practice — it’s often a council requirement. One of the most effective ways to achieve this is by installing a retention tank. But when exactly is a retention tank the right solution?

Let’s explore the key scenarios where a retention tank is not just recommended – it’s essential.

What is a Retention Tank?

A retention tank is an underground or above-ground water storage system designed to hold stormwater or rainwater for reuse. Unlike detention tanks, which slowly release water into the stormwater network, retention tanks store water permanently for non-potable uses such as irrigation, toilet flushing, or wash-down.

When to Use a Retention Tank

1. When On-Site Water Reuse is a Priority

If your project involves rainwater harvesting for re-use in the home, garden, or commercial facility, a retention tank is ideal. It stores clean water that can be filtered and reused, reducing reliance on mains supply and lowering water bills.

2. When Council Consent Requires Water Reuse or Stormwater Management

Many local councils now include water reuse or retention targets in building consents for residential and commercial developments. Installing a retention tank helps meet these requirements and demonstrates commitment to sustainable water practices.

3. When Building on Sites with Poor Drainage or Limited Stormwater Access

In areas where connection to public stormwater systems is limited or non-existent, retention tanks offer an on-site solution. By capturing water for later use or slow release, they help prevent surface flooding and reduce runoff.

4. When You Want to Add Sustainability to Your Project

Retention tanks are a great way to align your build with green building standards or environmental certifications. They also support climate resilience by making properties less dependent on external water sources during dry periods.

Integrated Retention Solutions from APD

Our retention tank systems are designed for New Zealand conditions. Whether you need a standalone tank or a combined retention + detention system, we can help you size, design, and install a solution that works for your site.

APD’s retention tanks integrate seamlessly with our full range of underground systems — including StormLite®, StormSlim®, and StormSlab® — delivering a flexible, durable, and compliant solution for any project.