Combined Sewers and Your Paterson Home: What Backs Up, Why, and What to Do
Paterson's combined sewer infrastructure is one of the primary causes of residential water damage in the city. This guide explains how the system works and what happens in your basement when it fails.
What a combined sewer system is and why Paterson has one
A combined sewer system is a municipal infrastructure design in which a single pipe network carries both storm runoff and sanitary sewage. This approach was the engineering standard for American cities built before roughly 1950, which means most of the original sewer infrastructure underlying the oldest parts of Paterson is combined. During dry weather, the system works exactly as intended: sanitary waste flows from buildings through the lateral, into the main, and on to the treatment plant. The problem is rain.
When a significant storm drops rainfall on an urban landscape with as much impervious surface as central Paterson — roofs, streets, sidewalks, parking areas — the runoff enters the combined system immediately and massively. A one-inch rain event over a few hours can generate more stormwater volume than the combined system was ever designed to carry, and the system's safety valve is the combined sewer overflow structure: a point where the excess discharges directly to the Passaic River rather than backing up further into the collection network. This is a legal, permitted discharge event under the state's combined sewer overflow program, but it does not prevent all pressure from building in the system. In the most intense events, or when multiple systems are simultaneously overloaded, the pressure relief comes wherever the system finds the path of least resistance — including upward through the floor drains and toilets of the lowest-elevation properties on the line.
The anatomy of a backup in a Paterson row house
The first sign is almost always the basement floor drain. It may start as a slow gurgle, or it may appear as standing water forming around the drain cover with no obvious source. In a building with a sub-grade bathroom, the toilet may be the first sign — a bubbling bowl or a very slow flush during heavy rain. What is happening is that the hydraulic gradient in the combined main in the street has reversed: instead of flowing from your building toward the treatment plant, the pressure in the main is pushing back toward your building. Your lateral, which connects your building's drain system to the main, is now under positive pressure from the outside rather than negative. The weakest point in that system — usually the floor drain, the lowest trap — is where it surfaces.
Older properties with deteriorated or missing trap seals on the floor drain are particularly vulnerable, because a functional trap requires a water seal to be present. If the floor drain has not been used in months, the trap may have evaporated dry, leaving a completely open conduit between your basement floor and the city combined main. This is one of the reasons we recommend that property owners periodically pour a quart of water into infrequently used basement floor drains to maintain the trap seal, especially before forecast storm events.
The difference between a drain backup and a plumbing failure
The distinction matters for both cleanup and insurance purposes. A sewage backup that originates from the municipal system — surcharge from the combined main pushing back through your lateral — is typically not covered under a standard homeowner policy unless you have specifically added a water-backup or sewer-backup endorsement. A plumbing failure inside your property — a broken sewer lateral under your foundation, a failed wax ring on a toilet, a blocked internal drain line that overflows — is a different cause code and may be covered differently depending on your policy language.
The practical difference at cleanup time is that a municipal backup event affects all of the properties on a given block or main simultaneously, and the City of Paterson's DPW typically receives multiple calls in the same timeframe. Documenting the date and approximate time of the event, noting whether neighbors experienced the same issue, and calling us promptly so we can assess while the loss is fresh all serve your documentation for the claim. A municipal backup also typically carries contaminated water from the sewer system, not just rainwater, so the cleanup protocol is a Category 3 biohazard response regardless of how it looks on the surface.
What happens during the cleanup
Paterson Water Repair responds to combined-sewer backup events with personal protective equipment, containment, and a sequence designed for contaminated water. We extract the standing water, remove all porous materials that contacted the backup — carpet, padding, drywall below the water line — and then scrub and disinfect every hard surface with an EPA-registered disinfectant appropriate to the pathogen load of sanitary sewage. The space is not cleared until post-treatment air quality and surface testing confirms it is within safe parameters. If there is any possibility that the backup reached heating or ventilation equipment, we include those in the treatment scope.
After the mitigation phase is complete, our reconstruction team can handle the replace-out of flooring and drywall so you are not coordinating between two separate contractors. Call 551-351-9704 to reach a Paterson Water Repair team member at any hour. For properties where the backup has been slow and the space has been damp for days before discovery, our mold assessment crew will often walk the space at the same time to identify any secondary growth that is already underway so it can be addressed in the same remediation scope.
Backflow preventers: the single best investment for a Paterson basement
A backflow preventer, also called a check valve or backwater valve, is a mechanical device installed in your sewer lateral that allows flow in only one direction — out of your building toward the main. When the main surcharges and flow reverses, the valve closes automatically, preventing the sewage from reaching your floor. It does not prevent all flooding — it does nothing for groundwater intrusion or for water entering through windows or doors — but it completely eliminates the backup-through-the-drain failure mode for as long as the valve functions.
Installation requires excavating to reach the lateral, which is typically a half-day job for a licensed plumber. The cost in the greater Paterson area runs roughly $800 to $2,000 depending on depth and access. That is a one-time expense that eliminates a recurring loss exposure in a neighborhood where combined-sewer backup events happen multiple times per decade. For owners of multi-unit properties near the Passaic River corridor or in other low-lying sections of the city, the math is straightforward: one prevented event pays for the valve many times over. The City of Paterson has in the past offered limited rebate programs for backflow prevention installations as part of its CSO reduction commitments; it is worth checking with the DPW for any current incentives before having the work done.
After the repair: preventing the next event
Once a property has experienced a combined-sewer backup, several structural habits significantly reduce the odds and severity of the next one. First, install the backwater valve as described above if one is not already present. Second, ensure all infrequently used basement drains have functioning traps with water seals and check them seasonally. Third, have your sewer lateral inspected with a camera — lateral defects like root intrusion, joint separations, or partial collapses create low spots where sediment accumulates and increases backup frequency independent of the municipal system condition. Fourth, during extended dry periods before a major storm is forecast, make sure the sump pump is operational — a sump pump that has sat idle through a dry summer may have a seized float or a clogged impeller and will not be ready when you need it most.
The geography of Passaic County means that preparedness cycles follow the calendar in predictable ways. Fall brings the Nor'easter season; spring brings snowmelt and April rain events that historically produce the highest Passaic River readings of the year; summer brings the short-duration high-intensity convective storms that can dump two inches of rain in forty minutes on a Paterson block and overwhelm the combined system before the water has anywhere to go. Mapping your property's specific exposure — basement floor drain, window wells, foundation-wall seepage paths — against this seasonal pattern lets you prioritize the mitigation investments that deliver the most protection for the most likely threat at any given time of year.
Paterson Water Repair responds to sewer backup events twenty-four hours a day. We are dispatched from 85 Fulton St #04 and can be on-site fast. Call 551-351-9704 for immediate response. If you have questions about what category of loss you are dealing with, our team will give you a straight answer on the phone before we arrive.