Understanding Sanitary and Storm Sewer Systems

Water moving through a city may look similar at the surface, but it can enter two very different drainage systems. Sanitary sewers carry wastewater from toilets, sinks, showers, washing machines, and commercial facilities. Storm sewers collect rainwater and snowmelt from streets, roofs, parking areas, and other outdoor surfaces.

Knowing the difference helps residents dispose of water correctly, recognize potential problems, and protect local infrastructure. It also explains why a blockage in a household sewer line requires a different response from flooding around a storm drain.

In Susanville, public infrastructure includes wastewater collection, streets, stormwater facilities, and other systems that support health, safety, and daily life. Understanding how each system works helps residents report concerns accurately and reduce preventable damage.

How sanitary sewers carry wastewater

A sanitary sewer is designed to transport used water to a treatment facility. Household plumbing connects to a private sewer lateral, which then connects to the public sewer main. From there, wastewater flows through a network of pipes, manholes, and lift stations before treatment and permitted discharge.

This system receives water that has been intentionally used indoors. Toilets, bathroom sinks, kitchen drains, and laundry connections are common sources. Commercial properties may send wastewater into the same network, provided the discharge meets applicable requirements.

Sanitary sewers are not built to handle large volumes of rainwater. When roof drains, sump pumps, yard drains, or damaged pipes send stormwater into the sanitary network, the added flow can overload pipes and treatment facilities.

How storm sewers manage runoff

Storm sewers, sometimes called drainage systems or municipal separate storm sewer systems, are designed to move runoff away from streets and developed areas. Water typically enters through curb inlets, catch basins, culverts, drainage channels, and other surface structures.

Unlike sanitary wastewater, stormwater may receive little or no treatment before it leaves the drainage network. Runoff can carry soil, oil, litter, lawn chemicals, sediment, and other pollutants into local waterways. For that reason, storm drains should receive rainwater and permitted outdoor runoff—not household wastewater or hazardous materials.

During intense rainfall or rapid snowmelt, storm drains may fill quickly. A temporary pond near a grate does not always indicate a sewer failure, but blocked inlets, damaged structures, or water entering a building should be reported promptly.

The differences that matter

The two systems differ in purpose, connections, maintenance, and environmental impact. A sanitary sewer problem often appears inside a building through slow drains, backups, or wastewater odors. A storm drainage problem is more likely to appear outdoors as standing water, erosion, clogged inlets, or flooding near streets.

Feature	Sanitary sewer	Storm sewer
Primary purpose	Carries wastewater for treatment	Moves rainwater and snowmelt
Typical sources	Toilets, sinks, showers, laundry	Roofs, streets, parking lots, yards
Common structures	Sewer laterals, mains, manholes, lift stations	Catch basins, curb inlets, culverts, drainage channels
Water quality concern	Untreated sewage can create health hazards	Runoff can carry pollutants to waterways
Typical warning signs	Slow drains, sewage odors, indoor backup	Street ponding, clogged grates, outdoor flooding
Appropriate disposal	Household wastewater and approved discharges	Rainwater and permitted surface runoff

Never connect a sanitary fixture to a storm drain, and never use a storm drain to dispose of wash water, paint, grease, chemicals, or sewage. Incorrect connections can cause contamination, regulatory problems, and expensive repairs.

Recognizing backups and drainage problems

A sanitary sewer backup may begin with several fixtures draining slowly at the same time. Gurgling toilets, repeated clogs, sewage odors, or wastewater rising from a floor drain can indicate a blockage in a private lateral or a public sewer main. Stop using water if a backup is occurring, keep people and pets away from contaminated areas, and contact the appropriate emergency or maintenance resource.

Homeowners can reduce risk by keeping grease, wipes, paper towels, diapers, and other unsuitable materials out of drains. Regular plumbing maintenance, proper cleanout access, and a functioning backwater valve where appropriate can also help. Additional sewer backup guidance explains practical ways to protect a property.

Stormwater issues require a different assessment. Residents may notice a blocked catch basin, a damaged grate, sediment accumulation, or runoff crossing a sidewalk. Avoid removing a grate or entering a flooded roadway. Report the location and describe whether the issue involves debris, erosion, standing water, or damage to a public structure.

Public and private system responsibilities

The public sewer main and the private sewer lateral are separate parts of the wastewater system. Responsibility for a lateral, cleanout, or plumbing connection can depend on location, ownership, easements, and local requirements. A licensed plumber may be needed to inspect a private line, while the Public Works Department can evaluate concerns involving public streets, mains, or drainage facilities.

Residents should obtain required permits before altering sewer connections, installing drainage improvements, or performing work in the public right-of-way. Unapproved work can damage underground utilities or direct water onto neighboring property. Before excavation, contact the appropriate underground utility locating service and review applicable city requirements.

Stormwater improvements also need careful planning. Paving, grading, retaining walls, roof drainage, and landscape changes can alter where runoff travels. Engineering review may be necessary when a project affects streets, sidewalks, drainage easements, or other public infrastructure.

Keeping both systems working well

Everyday choices help preserve capacity in sanitary and storm drainage networks. Keep leaves, sediment, trash, and yard debris away from curb inlets. Direct downspouts in a way that does not create erosion or send concentrated flow toward a building, sidewalk, or neighboring property.

The following practices support reliable service and cleaner runoff:

• Flush only toilet paper and human waste; place wipes and other products in the trash.
• Collect cooking grease and dispose of it according to local guidance rather than pouring it into a drain.
• Sweep driveways and sidewalks instead of washing dirt and debris into storm drains.
• Maintain private sewer cleanouts, plumbing fixtures, and drainage channels.
• Report sewage odors, repeated backups, blocked inlets, flooding, and damaged public facilities promptly.

During a storm, use caution around standing water and avoid contact with water that may contain sewage or roadway pollutants. Do not drive through flooded areas when depth and road conditions are uncertain.

Finding local information and reporting concerns

The City of Susanville Public Works Department provides information about municipal utilities, streets, stormwater, engineering, permits, projects, emergency contacts, and related services. Residents can use the Public Works website to find current contact details, utility resources, conservation information, and department updates.

When reporting a problem, include the street address or nearest intersection, the type of issue, when it began, and whether water is entering a building. Photos may help document outdoor drainage conditions, but personal safety should come first. Clear details allow staff to distinguish a private plumbing concern from a problem affecting public infrastructure.

Learning which system serves a property is a practical step toward protecting health, homes, roads, and waterways. Use the department’s current contact and service information to report urgent conditions and get the right guidance before beginning drainage or sewer work.