Storm drains play a pretty important role in modern civilization and work behind the scenes to prevent flooding and damage to your homes and cities. When rainfall occurs, water flows from streets, sidewalks, private property, and rooftops into storm drain inlets, which are those metal grates you see along curbs.
From the inlet water enters underground pipes flowing to catch basins and culverts, ultimately reaching stormwater ponds, dry wells, or treatment facilities. Maintaining drainage pipelines helps manage runoff, prevent erosion, and keep roadways safe by efficiently diverting water away from neighborhoods, homes, and businesses. Homeowners can also help by keeping the drains outside free of debris like leaves or trash that could clog the system.
What is the Purpose of a Storm Drain?
One of the most most obvious and important things that they do is stop streets and properties from flooding.
Without them, streets flood and cause basements to flood. Definitely not something that anyone wants to deal with.
They also protect the land. When rain flows freely, it washes away soil and dumps dirt into streams. Storm drains control this flow, preventing erosion and keeping waterways clear.
Storm Drain Anatomy
Storm drains might look simple this intricate underground system keeps roads and yards from turning into small lakes whenever it rains hard. There are five main steps that the storm drains go though:
1. Inlets (storm drain hardware)
What are those slots along curbs or metal grates in the pavement, yards, or the bottom of stairwells? That’s where rain begins its journey underground. They catch water running down streets, sidewalks, or onto yards, preventing puddles from forming where you walk or drive. Next time it rains, watch how quickly water disappears through these openings. Remember, in the Wintertime these puddles ice over and become slip and fall hazards.
2. Catch Basins
Once past the catch basin, water flows through a network of pipes – some small, others big enough to walk through. These hidden passages carry water beneath your feet, your car, even beneath entire buildings. They’re like secret rivers running under the city.
3. Pipes and Culverts
Once inside the system, storm water flows through a network of underground pipes, connecting catch basins to larger culverts—massive pipes that transport water beneath roads, railways, and buildings. Think of it as a subway for storm water, efficiently moving water where it needs to go while keeping the surface clear and flood-free.
In other cases, these pipes connect to tanks. These tanks are known as dry wells. Dry wells have weep holes that allow the rain water inside to seep into the ground surrounding the dry well. Dry wells have another benefit of relieving the stress of rain water on the public sewer system.
4. Manholes
Ever wonder about those heavy round covers in the street? They’re doorways that let maintenance crews check on what’s happening underground. Without them, fixing problems would mean tearing up entire roads.
5. Stormwater Ponds: Nature’s Holding Tanks
Eventually, storm water exits the drainage system into special ponds designed to manage runoff. Some hold water year-round, others dry out between storms. These ponds give dirt and pollution time to settle out before the cleaner water continues to lakes or rivers. They’re the final checkpoint before rainwater rejoins the natural water cycle.
In other cases, storm water goes to a municipal water treatment plant. Separate from, but along with the sanitary waste water. In both cases storm water intake must be monitored to prevent the improper disposal of pollutants and illegal acceptance of sanitary waste water.
Why Storm Drains Matter
When heavy rain hits, storm drains are the reason you can still drive down your street without a boat. Storm drains are more than just infrastructure—they’re a lifeline for communities. By reducing flooding, protecting water quality, and supporting sustainable practices, they keep our environment safe and functional.
Modern Additions To How Storm Water Is Handled
To lessen the burden on the public sewer system various changes have been implemented over the years.
Green roofs: A “green roof” is a specific type of roof that is designed to absorb and retain rain water, lessening the flow reaching the storm sewer system.
Bioswales: These are structures that are installed inside the curb line that may look like a tree pit, but they are much more than that. A bioswale is a carefully engineered underground structure that absorbs and disperses a large volume of rain water. It likewise lessens the burden on the public sewer system, and aloes greatly reduces street flooding.
Detention Tanks: Similar to a dry well, only a detention tank only detains the flow of storm water for a period of time. It allows the storm water to flow out to the sewer at a reduced rate, greatly reducing the chance of a sewer getting overburdened and causing flooding.
