Storm Sewer System: What They Do and How They Operate

When it rains, do you ever wonder where all that water goes and why it doesn't flood your community?

Do you know how many storms and sanitary sewers you pass when you walk down the streets?

How exactly do these two sewers work, and what makes them different? Why must they be kept separate? And how do they help our daily lives?

We answer all of that and more!

What Are Storm Sewer Systems?

Storm sewers, also known as storm drain systems, are where groundwater, rainwater, melting snow, and overflowing lawn water can be caught and slowly released back into the rivers, streams, ponds, and other bodies of water.

What Is the Main Function of Storm Sewer Systems?

When too much rainwater or melting snow does not permeate the ground or drain away through storm drains, it flows overground and causes flooding and soil damage.

The main purpose of a storm drain is a system designed to prevent flooding and soil erosion caused by stormwater by letting the water flow through underground pipes.

Stormwater is then controlled and stored through the storm drain system and released to rivers, streams, or the ocean.

How Do Storm Sewers Work?

When stormwater pours on the ground, it either ends up being absorbed by the soil or flows through storm drains on the streets.

From there, they are collected into catch basins, where water is transported to a system of underground pipes and open ditches.

These drainage systems are usually found in streets and some parking lots.

Then, as the stormwater makes its way to the storm sewers, it collects street garbage like grass clippings, animal waste, and other water pollutants.

After collecting rainwater from the storm drain inlets, it goes through pollution traps to catch waste materials and other debris.

Next, the storm drain system releases the stormwater back into the rivers and ocean.

What Are the Differences Between Storm Sewers vs. Sanitary Sewers?

Storm drains are designed to collect rainwater, while sanitary sewers are designed to collect wastewater from homes and businesses.

Storm drains are usually found on the street and are about a foot or two below the ground.

Meanwhile, sanitary sewers are around eight to nine feet below the surface since the water flow uses gravity and can drain from basements.

Sanitary sewer systems are similar to storm sewers, except the water has to go through a very thorough wastewater treatment facility.

Water from storm sewers is not significantly contaminated, so it doesn't need treatment like sanitary sewer water before being released to the discharge points.

What Are the Advantages of Storm Sewer Systems?

Here are some of the advantages of using storm sewers:

Prevents Floods and Soil Erosion

The biggest advantage of storm sewer drainage systems is preventing rain runoff from causing flooding and soil erosion.

By preventing flooding, the water stays on the road and empties through the nearest storm drain instead of collecting in the street and flooding your home or making the roads unsafe to drive on.

Reduces Ice on the Roads During Winter

During winter, it also reduces the amount of ice on the roads since the runoff empties into a drainage system, making the roads safe for travel.

It Lets Runoff Drain Faster

Because a storm drain system lets the runoff drain faster, it also helps keep crops and plants alive, resulting in more crop yield in rural areas.

Storm sewer drains also decrease water runoff and protect the soil structure from being damaged by rainwater.

What Are the Disadvantages of Storm Sewerage Systems?

Storm runoff does not go through wastewater treatment plants. Because of this, its disadvantage is stormwater pollution:

Chemical Pollutants

Since everything in the environment eventually ends up in the storm drainage system, chemicals used in your gardens, lawns, and pesticides all contaminate the water.

Sometimes, people dump motor oil, cooking oil, chemicals, paint, and other hazardous substances into a storm sewer drain, thinking it's safe to discharge them.

However, since none of the water goes through a wastewater treatment plant, that pollution goes back to our local waterways and harms us.

Other Pollutants

Debris, like grass clippings, street trash, and other materials, get swept up by the rain into the storm sewers.

Although they are not hazardous waste like motor oil and chemical cleaners, they all still end up in the storm sewer drainage.

And if they accumulate too much trash, it can clog up the sewer drain and defeat the purpose of the entire storm sewage system by blocking the flow of water.

Someone has to clean them up regularly to prevent debris from accumulating and reduce pollution.

Conclusion

And that's all we have for storm and sanitary sewers!

In short, storm sewers collect storm water to safely release it back to bodies of water and prevent flooding after the rain.

On the other hand, sanitary sewers collect wastewater from our homes, kitchens, and bathrooms.

They are a separate sewer system to prevent cross-contamination, and the water goes through a treatment process before being released.

Meanwhile, storm sewage systems do not include a treatment process since the water is not significantly harmful.