Storm drain

Storm drains help with rain.

They take water away from roads and roofs. This keeps the streets dry. It helps stop big floods.

Some drains have metal grids on top. These grids stop large things from falling in. They also keep cars from falling in. These drains must be very strong. They are often made of iron.

Water flows through pipes under the ground. These pipes can be round or square. Most pipes are round. The water goes to a river or a lake. It can even go to the sea.

Storm drains help manage extra water. They take rain and groundwater away from hard surfaces. These surfaces include roads, sidewalks, and roofs.

Most drains have a way to let water in. Some use side inlets near the curb. Others use grated inlets. A grate is a metal grid. It stops people, cars, and big trash from falling in.

These grates must be very strong. They are often made of cast iron.

Below the grate, there is often a catch basin. This is a part that catches heavy dirt and small objects. The dirt settles at the bottom. This helps clean the water before it moves on. In warm places, these basins can hold still water. This water might become a home for mosquitoes.

The water travels through pipes. These pipes can be round, square, or oval. They are made of materials like concrete or plastic.

Most drains empty into a river, lake, or the sea. Some systems use geotextiles. These are special fabrics that let water pass but stop soil from clogging the pipes.

Storm drains are important tools for managing water. They collect extra rain and groundwater from hard surfaces. These surfaces include paved streets, sidewalks, and even roofs.

Without these drains, heavy rain could cause flooding in streets and basements. Some drains are small for houses, while others are huge for whole cities. They help keep our paths and roads dry and safe.

Water enters a drain in a few different ways. Some drains use side inlets located near the curb. Other drains use grated inlets, which are metal grids over the opening.

These grates are very strong to support heavy cars. They are often made of cast iron or reinforced concrete. The bars are spaced to let water through but stop big objects.

However, narrow slots can sometimes be tricky for bicycle tires.

Below the inlet, many systems have a catch basin. This is a part that acts like a trap for heavy dirt. As water flows in, sediment and small trash settle to the bottom. This keeps the main pipes from getting clogged with debris. In the United Kingdom, these are called gully pots. They are designed to hold water to block gases and rodents.

In warm places, cities might use oil or special biscuits to stop mosquitoes from breeding in the still water.

Once the water is in the system, it travels through pipes. These pipes can be circular, square, or even egg-shaped.

They are made from materials like concrete, brick, or plastic. Some modern systems use geotextiles, which are special fabrics. These fabrics let water pass through but stop fine soil from clogging the drain.

Most drains eventually empty into a large body of water. This could be a river, a lake, or the ocean.

Engineers work hard to design these systems to protect nature. In Seattle, a project called the Street Edge Alternatives Project mimics natural landscapes.

It uses ditches and plants to help water soak into the ground. In the United Kingdom, laws since 2010 require new projects to use sustainable drainage systems. These systems help water flow more like it does in the wild. This keeps our water cleaner and helps prevent flooding in our towns.

A storm drain is a vital piece of infrastructure designed to manage excess water. It collects rainwater and groundwater from impervious surfaces. These are hard surfaces that do not absorb water, such as paved streets, parking lots, sidewalks, and roofs.

Without these systems, heavy rainfall could lead to significant flooding in streets and basements. Storm drains range in scale from small residential dry wells to massive municipal networks. They are essential for keeping urban environments functional and safe during storms.

Water enters the system through different types of inlets. Side inlets are located next to the curb. They rely on openings under a stone or lintel to capture flowing water. Grated inlets use a metal grid to allow water to pass through.

These gratings are often made of cast iron or reinforced concrete to support heavy vehicle weights. The spacing of the bars is very important. If the bars are too far apart, they might be unsafe for pedestrians. If the slots are long and narrow, a bicycle tire might get stuck, causing a rider to lose control.

Immediately below the inlet, many systems include a catch basin, also known as a sump. This part acts as a first-line pretreatment for the drainage system. As water flows in, heavier sediment and street litter settle to the bottom of the reservoir. The excess water then overflows from the basin into the main sewer pipes. This process helps prevent large debris from clogging the pipes. In the United States, these basins do not always block sewer gases like methane or hydrogen sulfide. However, in the United Kingdom, they are called gully pots and are designed as water-filled traps to block gases and rodents.

Because catch basins often hold stagnant water during dry periods, they can become breeding grounds for mosquitoes. In warm climates, cities may use several methods to control this. They might use larvicides, which are special chemicals often called "mosquito biscuits." Another method is to spread a thin layer of oil on the water surface to stop larvae from breathing. Some systems even use an inverted cone filter to physically stop mosquitoes from reaching the water. To keep the system working, municipalities use large vacuum trucks to clean out the collected sediment.

Once the water passes the catch basin, it travels through a network of pipes. These pipes come in many shapes, including circular, rectangular, square, oval, or even egg-shaped. They are constructed from various materials such as brick, concrete, galvanized steel, or high-density polyethylene.

Modern engineering often uses geotextiles in these systems. Geotextiles are synthetic fabrics designed to filter water. They are laid in trenches filled with stone or gravel. The fabric allows groundwater to seep through while preventing fine soil particles from clogging the drain. This is often more cost-effective than using expensive stone aggregates alone.

Most storm drains eventually reach an outlet where they discharge into a large body of water. This could be a river, a lake, a sea, or an ocean.

It is important to note that many storm drains are gravity sewers. This means they carry untreated water directly to natural water sources. Because of this, any hazardous substances poured into a drain will contaminate the destination water. Some systems are combined sewers, which intentionally mix stormwater with sewage. Other systems are designed to carry only stormwater, known as storm sewers or surface water sewers.

Modern engineers are now looking for ways to make drainage more sustainable. In Seattle, the Street Edge Alternatives Project creates drainage that mimics natural landscapes. Instead of just using pipes, it uses ditches and plantings to help water soak into the ground. This project reported a 99 percent reduction in stormwater leaving the area. Similarly, the United Kingdom has implemented Sustainable Urban Drainage Systems (SUDS). Since 2010, UK law requires new developments to include these systems to mimic natural water flows. These advancements help protect the environment while managing urban runoff effectively.