A retention or detention is an outlet added to the tank. The size of the outlet is usually 25mm or 32mm. This outlet is added for the slow release of water into the storm water.

Local councils will often specify the literage or amount of water that is required to be retained for storm water. The purpose of a retention/detention is to slow the release of water into the storm water in an attempt to ensure the local council storm water system will not be overrun with a huge surge of water causing drains not to cope. This extra outlet is a simple addition.

There is a small fee charged to add the outlet (material and labour cost included). Please ensure you chat with us before you order your tank if you require a retention added.

It is best this is completed by the manufacturer rather than your plumber as an after market addition could result in tank leakage.