Emergency Plumbing
Plumbing Repairs
Water Heaters
Drain Cleaning
Sewer Service
Faucets & Fixtures
Repiping
Toilet Plumbing
Trenchless
Plumbing Leaks
Air Conditioning
Heating
Minisplit Systems
Heat Pumps
HVAC Components
HVAC RebatesWhat is a Sewer System? Types, Components, and Maintenance
A sewage system is an underground network of pipes, pumps, and facilities that collects, transports, and treats wastewater and human waste from homes and businesses. The types of sewer systems are sanitary, storm, combined, overhead, vacuum, effluent, and pressure sewer systems, with each type designed to manage specific wastewater or stormwater conditions. Regardless of the type, a sewer system relies on several interconnected components to collect and transport wastewater, including sewer pipes and laterals, manholes and access points, pumping stations and interceptors, force mains and pressure pipelines, and treatment facilities and discharge units. Together, these components move wastewater through gravity or pumping toward treatment facilities.
Keeping these components operating properly requires routine sewer system maintenance, including regular inspections, periodic sewer cleaning, FOG control, I&I sealing, pumping station maintenance, root management, odor monitoring, asset management, and emergency planning. Proper maintenance helps prevent blockages, leaks, backups, overflows, and equipment failures. When hidden pipe problems are suspected, a sewer scope inspection uses a specialized camera to examine the inside of the sewer line and detect cracks, blockages, root intrusion, corrosion, and other defects.
What Is the Difference Between Sewer, Sewage, Sewerage, and Wastewater?
A sewer is the pipe that carries waste, whereas sewage is the waste and contaminated water moving through it. Sewerage describes the network that collects and transports sewage, while wastewater covers all water affected by domestic, commercial, or industrial use. These distinctions clarify how used water moves from its source through collection systems and toward treatment or disposal.
Below are the key differences between these four terms for a clearer comparison.
| Comparison Point | Sewer | Sewage | Sewerage | Wastewater |
| Meaning | A pipe or channel that carries wastewater | Wastewater containing human waste and contaminants | The infrastructure used to collect and transport sewage | Water affected by human use |
| What It Refers To | Physical conduit | Waste material | Complete collection system | Used water |
| Physical Form | Pipe, drain, or channel | Liquid waste mixture | Network of pipes and related infrastructure | Contaminated or used water |
| Primary Function | Carries sewage or wastewater | Flows through the sewer system for treatment | Collects and transports sewage | Requires treatment before reuse or discharge |
| Typical Source | Part of municipal drainage infrastructure | Toilets, bathrooms, kitchens, and buildings | Communities, cities, and municipalities | Homes, businesses, and industries |
| Example | Underground sewer pipe | Toilet wastewater | Municipal sewer network | Laundry or industrial process water |
| Key Distinction | The pipe | The waste | The system | The used water |
Is Wastewater the Same as Sewage?
No, wastewater is not always the same as sewage because wastewater includes many types of used water, while sewage specifically contains human waste. Wastewater is a broad term for used water from homes, businesses, and industrial activities. It can include water from sinks, showers, washing machines, manufacturing processes, and other sources. Sewage is a specific type of wastewater that contains human waste from toilets, along with organic matter and other contaminants. This distinction matters because different wastewater sources can contain different pollutants and require different treatment processes. The key distinction is that sewage falls under wastewater, while wastewater can exist without being classified as sewage.
How Do Sewers and Drains Differ?
A sewer is an underground pipe that transports wastewater from multiple sources, whereas a drain collects and carries water or waste away from a specific location, such as a sink, shower, toilet, or street. Drains connect individual fixtures, properties, or surface areas to larger sewer pipes. Sewers then transport the collected wastewater toward a wastewater treatment facility or disposal point.
Below is a comparison table showing the key differences between sewers and drains:
| Comparison Point | Sewer | Drain |
| Meaning | An underground pipe that transports wastewater from multiple sources | A pipe or channel that carries water or waste away from a specific location |
| Main Function | Moves collected wastewater toward treatment or disposal | Collects and directs water or waste into a sewer or drainage system |
| Typical Source | Receives wastewater from multiple drains and properties | Receives water from sinks, showers, toilets, roofs, or streets |
| System Role | Forms part of the larger sewerage network | Acts as a collection and connection point |
| Example | Municipal sewer pipe beneath a street | Sink drain or storm drain |
What Are the Main Components of a Sewer System?
The main components of a sewer system include sewer pipes and laterals, manholes and access points, pumping stations and interceptors, treatment facilities and discharge units, and force mains and pressure pipelines. Together, these factors move wastewater from its source through collection and treatment to final discharge.
5 main components of a sewer system are:
- Sewer pipes and laterals
Sewer pipes and laterals form the main collection network that moves wastewater from individual properties to municipal mains. Sewer pipes use gravity flow with a consistent downward slope and are commonly made from PVC, vitrified clay, or reinforced concrete. Laterals connect homes and businesses to these mains, typically measure 4 to 6 inches in diameter, and often maintain a 1 to 2% slope to prevent stagnation or reverse flow. Medium-sized cities may manage over 1,000 miles of sewer piping, with lines often installed below frost lines to reduce freeze-related failures.
- Manholes and access points
When a sewer line becomes blocked or needs inspection, manholes and access points give crews safe entry to buried pipelines through vertical shafts. Manholes are typically positioned every 120 to 150 meters and near junctions, directional changes, or elevation shifts. Often made from reinforced concrete, they can include lockable covers, non-slip rungs, cleanouts, and gas monitoring ports. Crews use these access points for CCTV or visual inspections, blockage removal, and routine maintenance, guided by standards such as ISO 24516-1:2016 to maintain system integrity and identify infiltration or structural deterioration before failures occur.
- Pumping stations and interceptors
For areas where the natural ground slope cannot keep wastewater flowing by gravity, pumping stations move wastewater to higher elevations so it can continue through the sewer system. Float sensors control pumps, while backup power and SCADA systems support continuous operation and real-time monitoring. Pumping stations direct wastewater into interceptors, which can exceed 36 inches (910 mm) in diameter and carry flow toward treatment plants. Individual stations may process 10,000 to 100,000 gallons per day, while large networks like Chicago’s Deep Tunnel integrate pumps and interceptors to manage wastewater and storm runoff.
- Treatment facilities and discharge units
Treatment facilities process collected sewage and wastewater to remove harmful contaminants before safely discharging or reusing the water. The treatment process uses physical screening to remove solids, biological treatment to break down organic matter, and disinfection to reduce harmful microorganisms. Large municipal plants can treat more than 100 million gallons per day while meeting applicable discharge regulations. After treatment, outfalls release clean effluent into approved waters such as rivers and lakes or direct it to reuse applications such as agricultural irrigation. Remaining sludge undergoes stabilization before reuse as fertilizer or disposal in regulated landfills.
- Force mains and pressure pipelines
Force mains and pressure pipelines are sealed sewer pipes that use pump pressure to transport wastewater where gravity flow is not practical. Connected to pumping or lift stations, they move wastewater uphill, across flat terrain, or over long distances using materials such as ductile iron, PVC, or HDPE. Key components such as air-release valves, check valves, isolation valves, and surge-control devices help regulate pressure, prevent backflow, and protect the pipeline from pressure changes. The pressurized flow continues until wastewater reaches a gravity sewer, interceptor, or treatment facility.
| Component | Primary Function | Common Materials | Maintenance Frequency |
|---|---|---|---|
| Sewer Pipes | Transport wastewater | PVC, Concrete | Every 5–10 years |
| Manholes | Inspection access | Reinforced Concrete | Annually |
| Pumping Stations | Elevation transfer | Metal/Composite | Monthly |
| Treatment Units | Waste processing | Steel/Concrete | Daily checks |
What Are the Different Types of Sewer Systems?
The main types of sewer systems include sanitary sewer systems, storm sewer systems, combined sewer systems, and overhead sewer systems, with storm and sanitary sewers differing mainly in the type of water they collect and transport. Each infrastructure manages wastewater, stormwater, or both based on its design, purpose, and connection to the wider sewer infrastructure.
Sanitary Sewer System
A sanitary sewer system is a network of underground pipes that carries blackwater and greywater from homes, businesses, and industrial facilities directly to wastewater treatment plants. Unlike storm sewers, sanitary sewers separate sewage from stormwater, helping keep rainfall out of the wastewater stream. Most pipes use gravity flow, while pump stations move sewage where natural slopes are insufficient. Common pipe materials include PVC, cast iron, and concrete, and urban sewer mains range from 8 to 24 inches in diameter, depending on service area and flow requirements.
Storm Sewer System
When rain, melting snow, or surface runoff collects on streets, roofs, sidewalks, and parking lots, a storm sewer system carries the water away to reduce flooding. The network uses catch basins, grated inlets, gutters, culverts, and reinforced concrete or metal pipes designed to handle high storm flows. Unlike sanitary sewers, storm sewers direct runoff separately to rivers, lakes, detention basins, or other receiving areas, reducing the load on wastewater treatment facilities. Cities such as New York and Tokyo use underground retention chambers, tunnels, and related drainage infrastructure to manage heavy stormwater flows and reduce urban flood risk.
Storm Sewer vs. Sanitary Sewer
A storm sewer is a drainage network that collects and carries rainwater, snowmelt, and surface runoff, whereas a sanitary sewer is a wastewater network that carries sewage from homes, businesses, and industrial facilities to a treatment facility. Keeping these networks separate also prevents stormwater from placing unnecessary pressure on wastewater treatment facilities.
Combined Sewer System
A combined sewer system uses one network of pipes to collect both sewage and stormwater runoff and carry the combined flow to a wastewater treatment facility. During heavy rainfall or snowmelt, the volume can exceed system capacity, causing a combined sewer overflow (CSO) that releases untreated sewage and stormwater into nearby waterways. To reduce these events, cities use overflow storage tunnels, flow regulators, and smart sensors to control excess flow. London’s Thames Tideway Tunnel is a large-scale example designed to capture combined sewer overflows before they enter the River Thames.
Overhead Sewer Systems
An overhead sewer system is a residential plumbing configuration designed to prevent sewage from backing up into a basement when a municipal sewer becomes overloaded. The system raises the building sewer above the municipal sewer backup level, while below-grade fixtures drain into a sealed ejector basin. A sewage ejector pump then lifts the wastewater through a discharge pipe, typically equipped with a check valve, before it enters the main sewer line. This configuration creates a higher discharge point that helps prevent sewer backups from reaching low-level basement drains and plumbing fixtures.
Alternative Sewer Systems: Vacuum, Effluent, and Pressure Sewers
Alternative sewer systems collect and transport wastewater in areas where conventional gravity sewers may not be practical. Vacuum sewers use negative air pressure to pull wastewater through sealed pipelines, while pressure sewers use pumps to push wastewater through pressurized pipes. Effluent sewer systems separate solids in a septic or interceptor tank and transport the remaining liquid effluent through smaller pipes. These sewer designs can serve areas with flat terrain, difficult ground conditions, or locations where deep gravity sewer installation is impractical.
How Does a Sewer System Work?
A sewer system works by collecting wastewater from homes, businesses, and other properties, carrying it through sewer lines using gravity or pumps, and transferring it to a wastewater treatment facility for treatment. Each stage keeps wastewater moving through the network until it reaches the facility where contaminants are removed before discharge or reuse.
Below are the 4 key ways a sewer system works:
- Wastewater Collection
Wastewater collection is the foundational initial stage where used water from residential homes, commercial properties, and industrial facilities is captured. When people flush toilets, run sinks, or use appliances, this wastewater exits through private plumbing pipes called lateral lines. These lines feed directly into local municipal sewer mains running underneath streets and sidewalks. This crucial stage ensures that hazardous biological waste, grease, and greywater are safely gathered from individual properties, preventing environmental contamination and public health hazards at the source.
- Wastewater Conveyance Through Sewer Lines
Once collected, wastewater is conveyed through an extensive, interconnected network of underground pipelines, manholes, and larger interceptor mains. Sewer mains gradually increase in diameter as they merge, consolidating regional flows from multiple neighborhoods into major trunk lines. Manholes strategically placed along these paths provide vital access points for municipal maintenance crews to inspect, clean, and clear blockages. This continuous underground transport network prevents sewage stagnation and ensures smooth, uninterrupted movement across miles of urban infrastructure.
- Gravity Flow and Pumping
Most sewer systems use gravity to move wastewater through pipes installed at a downward slope. The slope allows wastewater and suspended solids to flow toward lower points without continuous pumping. In flat areas, valleys, or locations where wastewater must travel uphill, gravity may not provide enough movement. Lift stations then use pumps to raise the wastewater and push it through pressurized pipes called force mains. The wastewater can later return to gravity-fed sewer lines where conditions allow.
- Transfer to Wastewater Treatment Facilities
The final operational stage involves transferring the accumulated wastewater to a centralized treatment facility where it undergoes rigorous multi-step processing. Facilities use physical screening, biological breakdown with bacteria, sedimentation tanks, and chemical disinfection to remove harmful pathogens, excess nutrients, and solid contaminants. Once treated to meet strict environmental standards, the purified water is safely discharged back into natural waterways, such as rivers and lakes, or reused for agricultural and industrial irrigation purposes.
What Happens to Wastewater After It Reaches a Treatment Plant?
After wastewater reaches a treatment plant, it undergoes screening, primary, secondary, and tertiary treatment before the effluent is discharged or reused and the sludge is treated for disposal. Each stage removes specific contaminants to prepare the wastewater for safe discharge or suitable reuse.
Below are the 6 key stages of wastewater treatment:
- Screening and Grit Removal
When wastewater enters a treatment plant, it first passes through screening and grit removal to separate large debris and heavy particles. Bar screens capture materials such as plastics, rags, paper, and wood that could block or damage treatment equipment. The wastewater then enters grit chambers, where the flow slows and allows sand, gravel, and other heavy particles to settle. Removing these materials protects pumps and pipes while preparing the wastewater for the next stage of treatment.
- Primary Treatment
After screening and grit removal, wastewater enters primary treatment to separate solids, oils, and grease from the water. The wastewater flows slowly through primary clarifiers, allowing heavier organic solids to settle at the bottom and form primary sludge. At the same time, oils, fats, and grease rise to the surface, where mechanical equipment removes them. This separation reduces the amount of solid and organic material in the wastewater before it moves into the biological treatment stage.
- Secondary Treatment
During secondary treatment, microorganisms break down organic matter that remains in the wastewater after primary treatment. The wastewater enters aeration tanks, where oxygen supports microorganisms that consume dissolved and suspended organic pollutants. This process creates biological flocs that can be separated from the water. The wastewater then enters secondary clarifiers, where these biological solids settle to the bottom. Removing this organic material improves water quality and prepares the wastewater for further treatment or purification.
- Tertiary Treatment
After secondary treatment, wastewater may undergo tertiary treatment to remove remaining contaminants. This stage can target fine particles, nitrogen, phosphorus, dissolved contaminants, and harmful microorganisms. Treatment methods can include sand or membrane filtration, activated carbon, chemical treatment, ultraviolet (UV) disinfection, and chlorination. The processes used depend on the required water-quality standards and the intended destination of the treated water, such as environmental discharge or an approved wastewater reuse application.
- Effluent Disposal or Reuse
Once wastewater completes the required treatment stages, the treated water is known as effluent and can be discharged or reused. Effluent that meets applicable water-quality requirements may be released into approved receiving waters, such as rivers, lakes, or oceans. Where regulations and treatment standards allow, treated wastewater can also support agricultural irrigation, industrial cooling, or landscape irrigation. Reusing treated water provides another water source for suitable applications and can reduce demand on freshwater supplies.
- Sludge Treatment and Disposal
The solids separated from wastewater during primary and secondary treatment are collected and processed as sludge. Because this material contains water, organic matter, and microorganisms, it requires further treatment before disposal or suitable use. Anaerobic digestion breaks down organic material and produces biogas, while dewatering removes excess moisture and reduces sludge volume. After treatment, the remaining material may be sent to a landfill, incinerated, or used as biosolids where treatment standards and regulations permit.
What Is the Difference Between a Public and Private Sewer System?
A public sewer system is owned and managed by a city, municipality, or public utility and serves multiple properties, whereas a private sewer system is owned and maintained by an individual property owner, business, or private group and serves a specific property or development. The main differences are ownership, maintenance responsibility, and the properties each sewer network serves.
When Is the City Responsible for Sewer Lines?
The city is responsible for sewer lines when a blockage, break, or structural problem occurs within the public sewer main or other municipal sewer infrastructure. This includes the main sewer pipe beneath streets, alleys, or public easements that collects wastewater from multiple properties. City responsibility covers blockages, breaks, or structural damage within the public main, as well as issues at the connection point where a private sewer lateral joins the main. For example, in San José, California, the City maintains sanitary sewer main lines and repairs damage and spills resulting from a blocked main. Property owners maintain the entire sewer lateral, but if an approved property-line “wye” cleanout is installed, San José will, as a courtesy, maintain the lower portion from that cleanout to the city sewer main.
When Is a Property Owner Responsible for Sewer Lines?
A property owner is responsible for sewer lines when a blockage, damage, or maintenance issue occurs within the private sewer lateral that connects the property to the public sewer system. In many municipalities, this responsibility extends from the building to the connection with the public sewer main, including portions of the lateral in a street or public right-of-way. For example, Redwood City, California, considers the portion of the sewer lateral from the property line to the sewer main the City’s responsibility, while the property owner is responsible for the portion on the owner’s side of the property line (Source: City of Redwood).
How Does a Sewer System Compare With a Septic System?
A sewer system is a centralized network that carries wastewater from multiple properties to a wastewater treatment facility, whereas a septic system treats wastewater on the individual property using a septic tank and drain field. Sewer systems rely on shared municipal infrastructure for wastewater collection and treatment, while septic systems operate independently and require property owners to maintain the tank and related components. Both systems manage household wastewater but differ in how and where they collect, treat, and discharge it.
| Feature | Sewer System | Septic System |
| System type | Centralized public network | On-site private system |
| Wastewater collection | Collects wastewater from multiple properties | Collects wastewater from one property |
| Treatment location | Wastewater treatment facility | Septic tank and drain field |
| Infrastructure | Sewer mains, laterals, pump stations, and treatment facilities | Septic tank, inlet and outlet pipes, and drain field |
| Maintenance responsibility | Municipality and property owner, depending on the component | Property owner |
| Common location | Urban and densely developed areas | Rural areas without municipal sewer service |
What Are the Key Benefits of a Sewer System?
The key benefits of a sewer system include protecting public health, reducing pollution and flooding, preventing exposure to untreated sewage, and supporting safe wastewater treatment, disposal, and reuse. These components help communities manage wastewater safely while protecting people, properties, and surrounding water sources.
9 key benefits of a sewer system include:
- Improve Public Health
Sewer systems improve public health by safely removing human waste and wastewater from homes, businesses, and public areas. According to the World Health Organization, unsafe sanitation contributes to approximately 564,000 deaths from diarrhoeal disease each year. This health burden shows why sewer systems are important: they contain sewage, limit human exposure to disease-causing pathogens, and transport wastewater safely to treatment facilities. By providing a controlled way to collect and transport waste, sewer systems support safer sanitation conditions across communities.
- Prevent Disease Outbreaks
When untreated sewage reaches drinking water, food sources, or areas where people live, harmful pathogens can spread through the community. Sewer systems reduce this risk by collecting human waste in closed pipes and carrying it to treatment facilities. Untreated sewage can contain pathogens associated with diseases such as cholera, typhoid, dysentery, and hepatitis A. WHO reported more than 560,000 cholera cases and over 6,000 deaths across 60 countries in 2024, with inadequate water and sanitation contributing to continued outbreaks. These outbreaks show why sewer systems are important for disease prevention: containing and treating sewage reduces opportunities for pathogens to contaminate water, food, and surrounding environments.
- Reduce River Pollution
Sewer systems reduce river pollution by collecting sewage and directing it to treatment facilities before discharge. Untreated sewage can introduce pathogens, suspended solids, organic matter, nitrogen, and phosphorus into waterways, contributing to oxygen depletion, algal growth, and degraded aquatic habitats. Wastewater treatment removes or reduces these contaminants, while regulated outfalls control where treated effluent enters receiving waters. This process limits untreated pollution entering rivers, lakes, and coastal waters and helps protect downstream water quality. Lower pollutant loads also help receiving waters maintain dissolved oxygen levels needed to support fish and other aquatic organisms.
- Minimize Urban Flooding in High-Risk Zones
In high-risk flood zones, storm sewer systems collect and carry excess rainwater and snowmelt away from streets, properties, and other developed areas. Storm drains, catch basins, pipes, and culverts direct runoff toward drainage channels, storage areas, or approved discharge points. This controlled flow reduces water buildup on roads and in low-lying areas during heavy rainfall. A 2026 study found that an urban drainage system reduced peak surface inundation volume by up to 50.92% and peak road inundation volume by up to 69.81% across modeled rainfall scenarios (Wang et al., 2026). As a result, storm sewer systems help reduce flood risks to homes, businesses, transportation routes, and other urban infrastructure.
- Eliminate Open Defecation Hazards
Sewer connections provide a contained sanitation system that helps communities move away from open defecation and uncontrolled disposal of human waste. Human waste left in open areas can contaminate soil and water and increase human contact with disease-causing organisms. Connecting toilets and properties to sewer infrastructure provides a controlled route for carrying sewage away for treatment. This improves sanitation and reduces direct exposure to human waste in populated areas.
- Cut Healthcare Costs
When sewer systems safely collect and treat wastewater, they reduce exposure to contaminated water and human waste that can cause sanitation-related illnesses. This lower exposure helps prevent diseases such as diarrhea, cholera, and typhoid, which may require medical treatment and cause people to miss work or school. As fewer people become sick from unsafe sanitation, households and healthcare systems can spend less on preventable medical care. Communities can also reduce productivity losses caused by illness and absence.
- Support Safe Wastewater Disposal
Sewer systems provide a controlled way to collect and transport wastewater from populated areas to treatment or approved disposal facilities. Instead of allowing wastewater to collect on the surface or enter nearby water sources untreated, underground sewer pipes keep the flow contained. Treatment facilities can then remove contaminants before discharging or reusing the water. This process supports safer wastewater management from collection to final treatment.
- Reduce Exposure to Untreated Sewage
When a sewer system carries wastewater away from populated areas, it helps prevent direct contact with untreated sewage. Wastewater from toilets, sinks, and other sources moves through underground sewer lines rather than collecting near homes, businesses, streets, or public areas. The sewer network then directs the wastewater to a treatment facility where harmful contaminants are removed. Safe collection and transport reduce exposure to sewage-related pathogens and help keep surroundings cleaner and more sanitary.
- Support Wastewater Treatment and Reuse
Sewer systems support wastewater treatment and reuse by collecting wastewater and delivering it to treatment facilities. After wastewater reaches the plant, physical and biological processes remove solids, organic matter, and other contaminants, while disinfection reduces harmful microorganisms. According to the WHO and UN-Habitat 2024 wastewater report, 82% of wastewater collected through sewer systems globally was delivered to urban wastewater treatment plants and safely treated in 2022. This shows how sewer networks directly connect wastewater collection with treatment and potential reuse.
What Problems Commonly Affect Sewer Systems?
Common sewer system problems include clogs and blockages, tree root intrusion, inflow and infiltration (I&I), cracked or leaking pipes, aging infrastructure, combined sewer overflows (CSOs), and stress from storm surges and flooding. These problems can restrict wastewater flow, increase pressure on sewer infrastructure, and lead to backups, leaks, overflows, or system damage.
7 problems that affect sewer systems are:
- Clogs and blockages
When grease, fats, oils (FOG), non-flushable wipes, and foreign debris accumulate inside sewer lines, they can restrict wastewater flow and eventually cause clogs and blockages. Over time, these materials solidify and create dense obstructions that restrict wastewater flow. This restriction increases internal pipe pressure, causing hazardous raw sewage to back up into home drains, basement fixtures, and public streets, and may require mechanical clearing or hydro-jetting.
- Tree root intrusion
Tree root intrusion is a common sewer problem that develops when roots enter pipes through cracks, gaps, or loose joints. Once inside, the roots grow toward the available moisture and can trap grease, waste, and other debris. As the root mass expands, it can restrict wastewater flow and cause recurring blockages. Continued root growth may also widen existing cracks, damage pipe joints, and weaken the pipe structure.
- Inflow and Infiltration (I&I)
When heavy rain falls or groundwater levels rise, inflow and infiltration (I&I) can affect the sewer system by adding excess water that increases flow and puts extra pressure on sewer lines and treatment facilities. Inflow enters the network through sources such as unsealed manholes or improper stormwater connections, while infiltration seeps through cracked pipes and damaged joints. As more unwanted water enters the network, the sewer has less capacity available for normal wastewater flow.
- Cracked sewer pipes
Cracked sewer pipes can disrupt wastewater flow and allow sewage to leak into the surrounding soil. Cracks may develop because of ground movement, soil erosion, heavy surface loads, or freeze-thaw cycles. Damaged areas can also allow groundwater to enter the sewer line, increasing the amount of water the network must carry. If cracks continue to grow, they can cause larger leaks, blockages, or partial or complete pipe failure.
- Aging Infrastructure and Leakage
For older sewer systems, aging infrastructure becomes a common problem as pipes, joints, and connections weaken after years of service. Clay, cast iron, and concrete pipes can develop corrosion, cracks, leaks, and joint failures that disrupt normal sewer operation. Damaged sections may allow wastewater to escape into surrounding soil or groundwater to enter the network. As deterioration continues, the risk of leaks, blockages, and pipe failure increases, requiring repairs, pipe lining, or replacement.
- Combined Sewer Overflows (CSOs)
During heavy rainfall or rapid snowmelt, combined sewer overflows (CSOs) can occur when the volume of sewage and stormwater exceeds the network’s capacity. Excess flow can then be released through overflow points into nearby rivers, lakes, or other receiving waters. Because the released water may contain untreated sewage, CSOs can introduce pathogens, organic waste, and other pollutants into waterways, creating water-quality and public health concerns.
- Storm Surge and Flood Event Stress
Sewer systems can experience serious stress during storm surges and flood events when large amounts of water enter the network or surround sewer infrastructure. Rising water can overwhelm sewer lines, flood pumping stations, and restrict normal discharge through outfalls. As pressure builds, wastewater may back up through property drains or overflow from manholes. Flooding can also damage pumps and electrical equipment, disrupting wastewater collection and transport until normal operating conditions return.
What Are the Best Practices for Sewer System Maintenance?
The best sewer maintenance practices include FOG control, proper disposal of non-flushables, tree placement, sump pump and downspout checks, cleanout access, and odor monitoring. They also include emergency planning, regular inspections, periodic cleaning, root management, I&I sealing, and pumping station maintenance. These methods help prevent blockages, leaks, equipment failures, and other problems that can disrupt wastewater flow.
12 key best practices for sewer system maintenance are:
- Control Fats, Oils, and Grease (FOG)
Keep fats, oils, and grease (FOG) out of drains because they can cool, harden, and build up inside sewer pipes, restricting wastewater flow. Installing grease traps and enforcing discharge limits are effective preventive measures. Homeowners can prevent FOG buildup by disposing of cooking grease separately, but recurring slow drains or blockages require professional sewer cleaning.
- Dispose of Non-Flushable Items Properly
Dispose of wipes, paper towels, hygiene products, and other non-flushable items in the trash rather than toilets or drains because these materials can accumulate and block sewer pipes. Homeowners can prevent clogs through proper disposal, but call a professional if persistent slow drainage or backups occur.
- Avoid Planting Trees Near Sewer Lines
Plant trees and large shrubs away from sewer lines to prevent roots from growing toward pipe joints, cracks, and other openings. Homeowners can handle this as a one-time preventive step during planting or landscaping, while existing root intrusion requires professional inspection and removal.
- Check Sump Pump and Downspout Connections
Check sump pump and downspout connections to ensure rainwater and groundwater drain to approved areas, not the sanitary sewer. Homeowners should check this every 6 months, but improper connections, damaged piping, or drainage problems may require professional repair.
- Know the Location of Your Sewer Cleanout
Locate your sewer cleanout and keep the access point clear so plumbers can quickly inspect, clean, or clear the sewer lateral during a blockage or backup. Homeowners typically need to identify its location once and check accessibility as needed, or contact a professional to locate or expose the cleanout if it is hidden, buried, or difficult to access.
- Monitor Sewer Odors
Check sewer odors around drains, toilets, basements, cleanouts, and outdoor sewer areas, as persistent sewage smells can indicate dry traps, venting problems, damaged seals, blockages, or sewer line issues. Homeowners should monitor sewer odors regularly and contact a qualified drain and sewer service provider if odors persist, recur, or occur with slow drains or backups.
- Plan for Emergencies
Create a sewer emergency plan that identifies the main shutoff points, sewer cleanout, emergency contacts, and steps to follow during a backup or overflow. Key elements include deploying a backup pump, routing a bypass, and coordinating the emergency team. Homeowners should review the plan annually, and when professional help is needed, hiring a qualified drain and sewer service provider helps ensure sewer problems are inspected and addressed properly.
- Conduct Regular Inspections
Inspect sewer lines regularly to identify cracks, blockages, corrosion, and other defects before they cause backups or pipe failure. Homeowners can monitor slow drains, odors, backups, and wet areas, while professionals should conduct video inspections, CCTV surveys, or sensor-based monitoring every 2 to 3 years or before buying or selling a home.
- Clean Sewer Lines Periodically
Monitor sewer odors around drains, cleanouts, basements, and outdoor sewer connections because persistent smells can indicate dry traps, venting problems, leaks, or sewer backups. Homeowners should watch for unusual odors on an ongoing basis and contact a professional if the smell persists, returns frequently, or occurs with slow drains or backups.
- Manage Root Intrusion
Inspect sewer lines for root intrusion when early signs such as slow drains or recurring backups appear. Homeowners can monitor these warning signs as needed, while professional inspection and root removal should be performed at the first signs of intrusion. Regular inspections help detect early intrusion, while removing roots from sewer lines early can prevent costly repairs.
- Seal Infiltration and Inflow (I&I) Sources
Seal infiltration and inflow (I&I) sources to prevent groundwater and stormwater from entering sanitary sewer lines through cracks, defective joints, or improper connections. Professional sealing or repair should be performed as needed after an inspection identifies the source and location of I&I.
- Maintain Pumping Stations
Manage pumping stations by checking pumps, valves, controls, alarms, and backup power systems to reduce equipment failures and interrupted wastewater flow. For commercial and municipal systems, professionals should perform maintenance monthly, whereas residential pumping stations typically require professional service as needed.
What Is a Sewer Scope Inspection?
A sewer scope inspection is a video examination of a home’s main underground sewer line that connects the house to a municipal main or septic tank. During the inspection, a sewer inspection professional inserts a flexible, waterproof camera through an accessible cleanout or drain to examine the inside of the pipeline. The inspection can identify hidden problems such as structural cracks, pipe collapses, tree root intrusion, grease clogs, and sagging pipe sections called “bellies.” For older homes and real estate transactions, a sewer scope inspection can help identify costly sewer problems before you buy a property.
How Much Does a Sewer Inspection Cost?
The cost of a sewer line inspection ranges from $150 to $,700. Inspection costs depend on the sewer line’s length, cleanout accessibility, required camera equipment, and local service rates. Some sewer inspection companies charge a fixed inspection fee, while others base the cost on inspection time. Video recordings, written inspection reports, and locating damaged pipe sections may also add to the final price. Factors that affect sewer inspection costs include the sewer line’s length, cleanout accessibility, inspection equipment, property location, and scope of the inspection. Some companies charge a flat fee, while others charge by the hour. Video recordings, detailed reports, and locating damaged pipe sections can also increase the total cost.
When Do You Need a Professional for a Sewer System Issue?
You need a sewer professional when a sewer problem involves recurring backups, slow drains throughout the property, sewage odors, damaged pipes, tree root intrusion, or wastewater surfacing around the property. Professional sewer services can identify hidden problems and determine whether cleaning, repair, or replacement is required.
Call a sewer professional if you notice:
- Recurring sewer backups
- Multiple slow drains
- Persistent sewage odors
- Wastewater surfacing around the property
- Suspected tree root intrusion
- Cracked, collapsed, or damaged sewer pipes
- Clogs that return after basic drain cleaning
- A need for camera inspection, pipe repair, or sewer line replacement
Frequently Asked Questions
Sewage is transported through pipes to treatment plants, where it undergoes various stages of purification. After flushing, waste flows through a home’s lateral sewer pipe to the main public or municipal sewer line. It is then carried by gravity or pumping to a centralized facility. There, it is treated to remove solids, organic matter, and pathogens. Once treated, the clean water is discharged into rivers or reused, and residual sludge is processed for disposal or reuse.
Common sewer problems include clogs, backups, and leaks, often caused by tree root intrusion, grease buildup, or aging pipes. These issues usually begin with subtle signs like slow-flushing toilets or gurgling drains, which signal that blockages may be forming. Non-flushable items and debris can accumulate over time, restricting flow and increasing pressure inside the pipes. Cracked or corroded pipes may also leak, allowing groundwater infiltration or leading to structural damage. Regular inspections and mindful disposal practices are key to reducing these risks and maintaining system health.
Your home uses either a public sewer system or a private septic system based on its location. Urban and suburban homes are usually connected to municipal sewer networks, while rural homes often rely on individual septic tanks. You can check your property records or ask local authorities to confirm which system you use.
Alex Hamilton is the owner of CPI Service, a trusted provider of plumbing and HVAC solutions. With over 35+ years of hands-on experience in the industry, He brings deep technical expertise and a proven track record in delivering reliable installation, maintenance, and repair services. His leadership ensures that CPI Service consistently upholds the highest standards of quality, safety, and customer satisfaction.
