Many public sewer systems serve hundreds of thousands of homes, businesses, and institutions and typically have thousands of miles of sewer pipe.  The majority of our sewer systems in the US are gravity fed, however lift and pump stations are common in parts of most large systems.  While there are many new systems, the typical systems range from about 25 years old to more than 100 years old.  In some cases, the sanitary sewer and the surface water sewers may feed common mains.

Whether it is called “wastewater”, “sanitary sewage”, or just plain “sewage”, what is sent through the sewer mains is contaminated water.  The contaminants are typically disposed chemicals, food waste, plant debris, paper, plastic, detergents, dirt, building materials, and human waste.  Some of the contaminants are soluble in water, most are not.  The water is used to carry these contaminants to various types of treatments facilities that are typically part of the system.  The contaminants are extracted, treated, and disinfected, and the water is then allowed to flow into a local river system or used for irrigation.

Causes of Backups

• Cracked or Deteriorated Sewer Pipes – Remember that most system are old.  These old sewers are mostly clay pipes which can crack as they deteriorate with age and also due to earth movement.  The mortar used to seal the joints between sections of older clay pipe may have deteriorated resulting in misaligned or open joints.  When a hole in the pipe system exists, it will grow and allow soil to become introduced.  This will then be a conduit for roots that could lead to expansion of the gap or fracture of the clay pipes. 
• Undersized Piping (based on inputs) – The existing sewer system has become overloaded due to new sewer hook-ups, water infiltration, and or illegal new sewer, roof or yard drain connections.  Discharging sump pumps into the sanitary sewer is also common, and illegal, and can overload a system.
• Defective manholes – Old manholes are made of bricks.  Typical problems associated with brick manholes are loose bricks, missing bricks, and misaligned manholes.  The deteriorated materials fall into the system piping.
• Missing and/or Unrecorded Sewer Pipes and Manholes – This problem is typical in older easement and backline sewers.  The lack of documentation means that waste sources which are contributing to the system are not accounted for and thus not factored in flow or maintenance schedules.
• Sewer Mains or Laterals Re-Routed – In some cases, a sewer line encountered during improvements is re-routed and joints or incorrect falls are introduced.
• Flat Spots or Sags in Sewer Main or Lateral – Can be due to poor installation, soil movement, or compaction due to heavy surface loads.  Sewer lines may be installed improperly if it is inconvenient to place the whole line at a the proper depth and pitch, such as below a ditch, installing a sag below the ditch. 
• Root Infiltration – Roots from vegetation are a major cause of backups and typically occur in laterals

• Water Inflow and Infiltration – This is not an obstruction, but the result of heavy or prolonged rainfall causing the sanitary sewer main to fill due to infiltration and inflow (I&I) of storm or surface water.  Some districts have had orders imposed upon them by the EPA or courts to reduce storm and surface water inflow and infiltration.  Much work has been done to eliminate I&I from sanitary sewers but there are still areas where this is a problem.  This often results in a surcharged main, and sewer backups result.
• Solids – Typical solids that are introduced or can buildup in the system and cause backups involving grease, dirt, bones, tampons, paper towels, diapers, broken dishware, garbage, concrete, and other debris that is too large for the system to handle.  In cases of commercial businesses, especially automotive shops and restaurants, introduced grease is responsible for a back-up.  It is common for the grease traps to be poorly maintained, undersized, or non-existent.  These all are potentially code violations that may be the responsibility of the property owner or the tenant.
• Vandalism – This usually involves an unauthorized person removing a manhole cover and dropping objects into the manhole and obstructing the flow.  Landscape and building materials are the most common.  This has occasionally resulted in a backup into a building, but generally results in a manhole overflowing.
• Service Connection Failure – The stoppage is caused because the main is broken and/or full of roots at the service line connection from a building.  Service connections are typically the responsibility of the property owner.

Dealing with a Sewer Backup:

Turn off all sources of possible inflow to the system and call your wastewater district; (municipality in most cases).  They can come out and give advice as to what the problem might be and help determine if it’s the property owner’s responsibility or the district’s.  They may also have maps showing the location of the sewer line on your property.

How Can a Backup be the Property Owner’s Responsibility?

Though each district is different, typically the home or property owner is responsible for the portion of the system that is inside their property line.  This portion is referred to as the sewer lateral, or service lateral.  The sewer lateral is owned (and thus presumed to be maintained) by the property owner including any part which may extend into the street or public right of way.  In some districts, the responsibility continues up to the actual connection to the main.  Some developments and apartment complexes incorporate a private sewer system that discharges into a main.  These private systems often have no specific maintenance program, but they do often have an association that has charge of the system.  Most districts have a page on their website that details who is responsible for what portion and where the responsibility changes.

More often than not, the cause of a backup in a sewer lateral is from items that the line is not meant to handle, such as toys, clothing, towels, diapers, and many other items.  Often small children are linked to the introduction of these items.  Also, remember that what you flush down the toilet may not affect you, but it might cause problems for your neighbors!  Grease and roots are also main causes of sewer lateral backups.

Condition Assessment to Determine Cause

• Physical Inspection – This involves examining the physical condition of manholes and other sewer structures to determine their structural integrity and to identify possible sources of I&I or obstructions.  Plans and or surveys may be necessary to complete this process.
• Flow Monitoring/Flow Isolation – Rainfall gauges are installed to monitor sub-basins with overflow problems by collecting and analyzing flow data during normal and storm related weather events.  Water flow may be introduced at a high point in the system to isolate areas of concern.
• Smoke Testing – Smoke testing is used to locate specific holidays in sewer mains and laterals that contribute infiltration/inflow to the sewer system.  Smoke testing involves injecting a non-toxic vapor (smoke) into the manholes and following its path of travel in the mains and laterals.
• Dye Water Flooding – Colored dye is added to surface or storm drain water. Dyed water appearing in the sanitary sewer system indicates an existing connection or dual breaching between the sewer and storm drain system.
• Closed-Circuit Television Inspection – This is a useful tool in locating specific sources of infiltration and obstructions as well as determining the structural condition of the sewer system.  This information is necessary for the design of sewer replacement and rehabilitation projects.  Electronic line locates are often conducted simultaneously.
• Sewer Maintenance Records – Records may indicate frequent maintenance problems and maintenance intervals and procedures.

Code

In most states, some form of a Public Health and Environment, or Water Quality Department will exist which regulates the collection and treatment of wastewater or sewage.  Most, if not all, will also require operators to be certified.  The certification involves coursework and testing.  Many states use the text referenced below in item 1.  One or more of the items listed below may serve as a standard of care or a regulation for a specific system:

1. Operation and Maintenance of Wastewater Collection Systems, (Volumes I and II, 6^th edition was current at the time of this paper), A field study training Operation and Maintenance of Wastewater Collection Systems prepared by California State University, Sacramento in cooperation with the California Water Environment Association for the U.S. EPA
2. Standards, rules or regulations promulgated by the specific district
3. State specific Statutes related to sewer line operation and maintenance
4. State Public Health and Environment, or Water Quality Department promulgated regulations, bulletins or rules for sewer line operation and maintenance
5. Uniform Plumbing Code
6. International Code Council Codes (IPC, IRC, IPMC).

Realize that if a legislative or code enforcement body has not adopted a specific document as code or regulation, then following the recommendations of that document is voluntary.  The rules and regulations of the specific district, in my experience, have always been in existence and should be viewed as the primary document with which compliance should be expected.

In every case I have worked on, a written procedure for inspection and maintenance of the lines was in effect.  However, the procedures for inspection may allow from 1 to 5 years for a specific section to be inspected.  Even then, the level of inspection may vary greatly from one district to another and is often based on the size of the district.  The district typically develops rules and regulations which apply to their operation of the sanitary sewer system.  In other districts, their property/casualty insurer may enforce intervals at which the system is to be inspected and/or serviced.  Typically included in these rules is a requirement to flush all lines at some time period, often one or two times per year.  Several methods are in use to maintain flow in the sewer systems throughout the United States.  Fire hydrants (which are often required to be flushed two times a year) are often used to flush the sewer lines by introduction through the manhole openings.  The next manhole downstream is opened to provides for visual inspection of flow.  This is an acceptable and common method of inspection and ensuring proper flow and flushing in a small, gravity flow sanitary sewer system.  The Operation and Maintenance of Wastewater Collection Systems training program has a suggestion for inspection and flushing once every 1 to 5 years.

There are several other routine methods including jetting, balling, rodding and others that are more common in large districts.  It should be noted that the more aggressive mechanical maintenance procedures have a very real possibility of damaging the sewer lines and creating a potential for pipe collapse and back up.

Citing the Operation and Maintenance of Wastewater Collection Systems training program referenced above, in section 12.401 it states:

The shotgun approach of “going through a system at set intervals with one piece of equipment” is wasteful and unnecessary.  Unfortunately, it is a common practice.

Certain procedures and practices may be suitable for one portion of a system and not the other.  In some cases, the “shotgun” approach has been satisfactory for large portions of the system, but has not sufficiently cleaned some small portions, or has damaged portions with older pipe.

It should also be noted that the standard of care for the operation of different sized systems is acknowledged by the States and the referenced training program.  For larger systems, the training and regulatory requirements increase.  The size and funding of larger systems adds funds and personnel, allowing for a higher degree of amortization of equipment.  The Operation and Maintenance of Wastewater Collection Systems training program also recognizes this fact.  In section 12.410 it states:

Many large organizations have purchased expensive equipment such as closed-circuit television or high-velocity cleaners and discovered a short time later, much to their disappointment, that similar but better equipment became available.  Because of the large investment, they have little choice but to keep and use their original equipment over a period of years necessary to amortize their original investment.

It recognizes the fact of budget constraints and that, even for a large district, they may not always be able to have or use the best equipment.  It is unreasonable to contend that small districts have the means, or should be required to operate on the level of the larger water districts, especially when regulatory and code provisions do not require it.

Investigation of Subrogation Potential from a Backup

Based on research and the numerous cases I have investigated, the issues are hinged on one of three things in most cases.

1. Blockages: If the lines are partially blocked due to neglect of long-term maintenance, then there is likely a subrogation potential, especially if the district violated their own procedures.  If there are blockages due to grease or other disposed items in violation of code or EPA regulations, then you have a decent case against the other insurer or user of the system.  If there are solids plugging the line, it may be advisable to evaluate flow and usage.  Changes in the volume of sewage to the system due to development and design parameters should be addresses as well.  From my perspective, the nice thing is that the cause is typically available to identify with a blockage.  If the blockage is due to roots in the sewer lateral, then responsibility will typically fall upon the property owner.
2. I&I: If there is heavy infiltration due to local flooding, that may prove to be a difficult case.  The case will likely be one of evaluating past occurrences and the appropriateness of the response of the district or municipality.  If it is a first-time occurrence, and the level of historical use of the system has not increased substantially, there is only a small chance of a success on a subrogation claim.
3. Fracture or Deterioration:  The causes vary, from aging to soil movement to damage from overburden.  If there is a large municipality with an aggressive inspection program, it is typical that these types of failures will be identified and corrected before a back-up occurs, provided the line is located.  Initial installation and overburden issues will often implicate someone other that the actual district, but often proves troublesome for successful subrogation.

Our research suggests, that in most States, the courts have ruled that a district is not an insurer of its system.  Thus, a district is not strictly liable for a backup.  However, subrogation based on negligence or nuisance often hinges on proof that the district had prior notice of a problem or defect in their system.  There are also rulings that support the contention that the district is bound to use reasonable diligence and care to ensure that their system does not clog or backup.

In any event, the controlling criteria for the inspection and maintenance will be the practices and procedures of the individual district.  On every case, that is the first thing I ask for, second are the drawings of the system, at least in the area of interest.  Third will be historical records for the area of interest, at least for the last five years.  I have found that in some cases, that attorneys have requested these documents from districts and advised that they were going to have an engineer look at them and the case literally went away.

Prevention

Prevention of back ups into a specific structure are related to one of two sources of the backup; either from (1) other users or system deficiencies, or (2) due to actions of the sewer system owner. When the backups are related to the main system, the following actions will typically solve the back up problem:

• Installation of backflow prevention devices in the sewer laterals, sometimes called backwater valves
• Installation of a self-contained pumping system, including ejector and grinder pumps
• Improvements to plumbing systems to support modifications

However, although you may prevent backup into a structure, that might not prevent back-ups of the main through manhole covers.

If the back-ups are due to obstructions in an otherwise sufficiently sized lateral with pipe integrity, a change in the introduced solids will typically solve the back up problem.  Cooking oils and grease should be poured into a heat-resistant container and disposed of, after it cools off, in the garbage, not the drain.  Some people assume that washing grease down the drain with hot water is acceptable.  As the grease goes down the drain it cools and solidifies either in the drain, the sewer lateral, or in the main sewer.  Paper towels, “flushable wipes”, disposable and cloth diapers and feminine products cause a great deal of problems in the sewer laterals as well as in the sewer mains.  These products do not deteriorate quickly, as does bathroom tissue.  They become lodged in portions of the lateral/main, causing a sewer backup.  In some cases, poor workmanship at the lateral connections may provide places for hair and tissue to catch.  In these cases, the pipe can be carefully reamed from the interior to provided better passage of solids.

Shrub and tree roots will make their way into sewer line cracks and joints.  These roots can cause extensive damage.  They may start out small, getting into a small crack in the pipe; but as the tree or shrub continues to grow, so does the root.  After time, this causes your sewer line to break, which in turn allows debris to hang up in the line, thus causing a backup.  One way to prevent roots from entering your line is to replace the sewer lateral with new PVC pipe.  The other alternative is to be careful about planting greenery around your sewer line.  If you have continuing problems with tree roots in your lateral, you may have to have them cut periodically.  If you have a plumber clean roots out of your lateral, it is advisable to contact the district so that they can flush or bail the debris introduced into the main line.

Fraudulent Repairs of Sewer Laterals

There have been numerous cases related to new home purchase inspections, or companies targeting areas and scaring homeowners into paying for installation of new sewer laterals.  While there certainly are cases where a sewer lateral needs to be replaced, the common practice is when an inspection company either shows a tape from another property where damage is present, and does not record a tape from a video sewer inspection of the property of concern.  Other companies do not have the expertise to evaluate what they see during an inspection.  Recently, the City of Arvada, CO sent a letter to all plumbing and drain cleaning companies who advertise in their area.  The city was very concerned about all of the complaints they have received from homeowners regarding companies overcharging, misinforming, and even blatantly deceiving their citizens.  It was a warning letter, and the complaints subsided as some companies left and went to other municipalities.