Rain and melting snow cause water to flow down from the mountains or the sky and into the drainage systems of many cities
. A city's sewers and a city's storm drains are often on separate systems, although both the sewers and the drains will end up in a sewage treatment plant in most cases.
When new towns are built or old systems get damaged, the owner of the property or the town that manages the system must replace the pipes to handle large amounts of water. Many tubes are made out of plastics or metals that have high resistance to corrosion. Most people choose durable plastics for small systems because the plastics are cheaper.
Small metal tubes are often used to go between ditches that run along the front yards of neighbors. A small tube setup occurs most frequently in rural settings where no municipal authority exists. Often these tubes stretch between properties owned by different people. These types of drains are usually made out of metal because getting the drains replaced requires an agreement between different property owners, which is often difficult to get.
Storm water drains and other types of devices used to remove excess rain and other types of water often are grooved in a spiral fashion. While the grooves provide a distinctive look, the grooves themselves serve a practical purpose. The storm drains are designed to trap dirt and sentiment inside and to allow water to flow freely over the grooves.
The usual place to install stormwater systems is underneath the ground. The devices generally get placed in a network where they flow downward. Either they tie into a municipal system or get installed in a private stormwater system. Rarely does a stormwater system flow directly into a stream, although this may happen if the drains and pipes are not installed to service industrial applications.