Stormwater Detention
The intensification of residential areas is placing more demands on stormwater networks. Bailey provide a range of storage solutions to meet council requirements

storm water tanks

Retention and detention FAQs

Both tanks are used to collect rainwater or storm water, the difference is in how the water is released. Detention tanks hold stormwater temporarily and release slowly, retention tanks store water for later use.

Storm water Detention tanks temporarily store rainwater collected from your roof via your gutter downpipe, that is slowly released into the council drain system. This prevents the council systems from being overwhelmed in heavy rainstorms, decreasing flooding risks.  

Storm water retention tanks collect rainwater from your roof, via your down pipe and store it for later use. Common uses are for watering the garden, or for an emergency water supply.  

Our full range of tanks is suitable for storm water retention or detention. The most common range used for storm water is our slimline range. We also offer a full package, or separate tanks and accessories for all storm water solutions. Click here to view this range.

There is no difference in the model of tank used, the difference is in how the tank is plumbed.  

Both tanks will have an inlet from your gutter’s downpipe. The outlet on a retention tank will have some form of ball valve – or “on off switch” While a detention tank will be plumbed into the council drainage system.  

We recommend you contact our team or a local plumber to assist in planning your storm water solution.  

Different councils have different specifications for storm water tank sizes, and specifications. The tank size is also based on your roof size and household needs. Please contact your local council for exact requirements to ensure your tank fits the specifications for your property. 


In general, a tank between 1000L and 3000L is required.  

Yes! These tanks are divided into two sections – above and below a small diameter orifice; the lower volume is for retention; the upper volume is for detention. Larger volume tanks are usually required for this system.

Retention water can be used in a variety of ways. Commonly this water is used for outdoor activities such as gardening, irrigation, washing the car. This water can also be plumbed into your house for use in your bathroom and laundry.  

A retention tank also offers a great back up for emergency water supply. Bailey Tanks are made of food grade polyethylene so the water will not be contaminated by the tank. Filtering and boiling the water is recommended as the quality of rainwater can vary.  

Stormwater refers to the runoff of water from urban surfaces generated by rainfall or melting snow. It is a major concern for New Zealand because of our varied climate and major storms. Proper storm water management is important in New Zealand to protect our ecological water ways and prevent urban flooding.