Stormwater
Rainwater is gathered from rooftops, gardens, wooded areas, and roads, among other places, and is either stored in rainwater tanks or directed away from buildings through a network of stormwater drains, which channel the water into lakes, streams, or oceans. Stormwater drains are specially designed to gather excess rainwater and surface runoff from impermeable surfaces.
Stormwater can be collected from various sources, including impermeable surfaces and subsoil. Subsoil water refers to the water accumulated just beneath the topsoil. Managing this water is important as it can impact the foundations of homes and retaining walls. Subsoil stormwater can be controlled using a French drain.
How is stormwater transported?
Stormwater is directed towards an appropriate destination, such as a rainwater tank or stormwater drains.
- Gravity-fed systems – The pipes are set up in a manner so that stormwater flows naturally through the drainage system due to gravity. The dimensions of the drainage pipes are determined by the level of rainfall in your region and the size of the area from which rainwater is being gathered.
- Pump based systems – They are essential when gravity alone isn’t sufficient to supply water to the drainage system. Pumps can also be installed in households equipped with a rainwater tank to channel the water into the tank.
Rain water storage
Rainwater can be harnessed on your property; when stored in water tanks, it becomes usable for household needs. Downpipes gather the rainwater and channel it into either a dry or wet pipe system.
Dry Systems
In dry systems, water doesn’t accumulate in the pipes but is instead directed towards stormwater outlet points, such as street curbs or stormwater connection points. The stormwater connection point is linked to the primary stormwater pipe.
Dry systems include surface grates or sumps placed in and around homes to collect water that accumulates in the yard. If there isn’t enough slope for gravity to naturally drain the water, sump pumps or soakage pits are employed to eliminate the surface water.
How do sump pumps work?
Sump pumps are employed to gather surface water, which is directed into the sump pump chamber. When the float valve senses an increase in the water level, it activates automatically and, through a pipe, pumps the water to the stormwater outlet point. Sump pumps are commonly utilized to eliminate stormwater from below-ground areas, such as basement carparks.
Wet or Sealed Stormwater Systems
Unlike dry systems, this type of system remains filled with water following a rainfall. When rainwater descends from the roof, it moves through the gutters and downpipes into the tank. There might be several downpipes connected to the rainwater tank, and in such cases, all the downpipes are connected to a common pipe, which is then linked to a vertical riser pipe for directing water into the storage tank. Whenever it rains, the water level in the rainwater tank rises. When the tank reaches its capacity, the excess water flows into the stormwater outlet.
The Significance of Stormwater Detention Tanks for Residential Properties
Another significant element of the stormwater drainage system is the Stormwater Detention Tank. Depending on your location, your local municipal authority may require you to install a detention tank. These tanks are used to assist local authorities in managing the volume of surface runoff, especially during heavy rainfall when the risk of flooding is higher. These tanks serve as a method to handle excessive stormwater runoff.
Within these tanks, rainwater and surface runoff are temporarily held. They are equipped with a valve to allow water to slowly exit towards the stormwater outlet point. This ensures that the water doesn’t all rush into the main system at once and overwhelm it, especially during periods of heavy rainfall.