Types of Stormwater Drainage Systems

Stormwater

The rainwater is collected from roofs, gardens, bushland, and roads, etc and is either stored in rainwater tanks or directed away from buildings using a system of stormwater drains which direct the water to lakes, creeks or oceans. Stormwater drains are designed specifically to collect the excess rainwater and surface run-off from impervious surfaces.

Stormwater can be collected from various sources like impervious surfaces as well as from the subsoil. Subsoil water is the water accumulated just below the topsoil. This water needs to be managed as it can affect the foundation of homes and retaining walls. Subsoil stormwater can be managed using a french drain.

How is stormwater transported?

Stormwater is transported to a suitable outlet like a rainwater tank or stormwater drains.

• Gravity-fed systems - The pipes are installed in a way that the stormwater goes through the drain systems using gravity. The size of the drain pipes depends on the intensity of the rain in your area and the size of the area from where the rainwater is collected.
• Pump based systems - They are necessary if gravity isn’t enough to feed the water to the drainage system. Pumps can also be installed in homes with a rainwater tank to direct the water to the tank.

Rain water storage

Rainwater can be utilised around your property, by storing it in water tanks it can be used for household purposes. Downpipes collect the rain water and feed it into either a dry or wet pipe system.

Dry Systems

In dry systems, the water doesn’t settle in the pipes and is directed to the stormwater outlet points like street kerbs or stormwater connection point. The stormwater connection point is connected to the mains stormwater pipe.

The dry systems consist of surface grates or sumps located around homes and collect water pooling in the yard. If there isn’t a sufficient slope that gravity can pull the water, sump pumps or soakage pit are used to remove the surface water.

How do sump pumps work?

Sump pumps are used to collect surface water which goes to the sump pump chamber. If the float valve detects a rise in the water level, it turns on automatically and pumps the water with the help of a pipe and sends it to the stormwater outlet point. Sump pumps are often used to remove stormwater from areas below ground level like basement carparks.

Wet or Sealed Stormwater Systems

Unlike dry systems, this kind of system is always full of water after a downpour. As the rainwater falls from the roof, it flows down into the gutters and downpipes to the tank. There could be multiple downpipes connected to the rainwater tank in which case, all the downpipes are linked to a single pipe which is then connected to a riser pipe to direct water into the storage tank. Every time it rains, the water level increases in the rainwater tank. Once the tank is full, the water flows to the stormwater outlet.

Stormwater detention tanks and their importance for homes

Another important feature of the stormwater drainage system is the Stormwater Detention Tank. Depending on where you live, your local council might ask you to install a detention tank. These tanks are used to assist the local councils with manageable loads of surface runoff. Especially during heavy periods of rainfall, there are higher chances of flooding these tanks are one way to help in dealing with excessive stormwater runoff.

In these tanks, the rainwater and surface runoff is retained for a limited time. They are fitted with a valve to allow water to escape slowly to the stormwater outlet point so the water doesn’t all rush to the mains at once and overwhelm the system.

Stormwater Drainage Solutions Sydney

If you need help with the installation of rainwater or detention tanks or maintenance for your stormwater drains, give our drainage specialists a call on 02 9191 7374 or complete our online enquiry form.