Combined Sewer Overflows in Hudson County: What Every Union City Property Owner Should Know
Union City sits on one of the oldest combined sewer systems in New Jersey. When it overflows, the water in your basement is not just water. Here is what it contains and how to respond safely.
What a combined sewer system actually does
Most of the United States built combined sewer systems in the 19th and early 20th centuries, and Hudson County is a prime example. A combined system carries both stormwater and sanitary sewage in the same pipe. Under normal conditions this is not a problem: the flow reaches the treatment plant, is processed, and the system functions as designed. The problem is capacity. When a significant rain event dumps water into the combined pipe faster than it can be processed, the system fills up and the excess, a mixture of stormwater and raw or partially treated sewage, has to go somewhere. That somewhere is called a combined sewer overflow, or CSO.
In Union City and across Hudson County, CSO events are documented and tracked by the state. They happen multiple times each year, concentrated in the spring and late-summer storm seasons when intense rain events overwhelm the infrastructure in a short window. When a CSO occurs, the backpressure in the sewer main pushes backward through the lateral pipes that connect individual buildings to the system, and the water surfaces at the lowest point in each building: the basement floor drain.
What CSO water actually contains
This is the point most homeowners and building managers do not fully reckon with until they are standing in it. Combined overflow water is not rainwater. It is a mixture of stormwater — which itself carries fuel, chemical residue, heavy metals, and biological material from streets, parking lots, and rooftops — and raw or partially treated sewage from residences and businesses across a large watershed. In restoration industry classification, this is Category 3 water, the highest contamination category, the same class as a direct sewage backup from the municipal main.
Category 3 water carries bacteria including E. coli and other fecal coliforms, viruses, protozoan parasites, chemical contaminants from street and industrial runoff, and whatever organic material happens to be in the sewer lateral at the time of the overflow. The contamination is not visible in the water once the solids settle, which is part of why it is dangerous: a basement that looks like it has a couple of inches of dirty rainwater may actually have a significant pathogen load that survives for days on the surfaces the water touched.
What you can and cannot do yourself
The first thing to understand is that CSO water in a basement is not something to wade into casually with rubber boots and a shop-vac. If you must enter the space to shut off electrical panels or retrieve critical items, wear rubber boots that cover the leg, nitrile or rubber gloves, and avoid touching your face. Do not eat or drink anything without washing thoroughly, and change and bag your clothing before coming inside. Do not try to extract the water yourself with a wet-vac and call it done — the contamination is not removed when the water is pumped out. It remains on every hard surface, in the pores of concrete, and on anything porous the water touched. The correct response treats the whole space as a biohazard until it is properly cleaned.
What you can do before the crew arrives: photograph and video everything, even if the water is still present. Document the depth, the affected areas, and the source — specifically, whether the water entered from the floor drain, the sump pit, a wall crack, or some combination. Document the date and approximate time it started. That record is the foundation of your claim. Then stay out.
The professional response: containment first
When Silva Water Damage CO responds to a CSO or sewage backup event in Union City, we treat it from the arrival exactly as the category 3 event it is. Our crew arrives in full personal protective equipment: Tyvek suits, face protection, nitrile or chemical-resistant gloves, and rubber boots. We set up a containment perimeter at the entrance to the affected space so that contaminated material and equipment do not leave that zone until it has been properly decontaminated.
The extraction sequence is deliberate: standing water first, then we remove porous materials that the contaminated water contacted. The list is not negotiable and it is not subject to negotiation with a building owner who wants to salvage the carpet: carpeting, carpet pad, drywall within the flood line, fiberglass or cellulose insulation, and any unfinished wood that the water was in contact with for more than a few minutes all come out. These materials absorb and hold contamination at a cellular level and cannot be decontaminated to a safe standard. Only hard, non-porous surfaces — concrete, metal, ceramic tile, glass, plastic — can be cleaned and disinfected in place.
The disinfection sequence, explained
After the porous materials are bagged and removed, every hard surface in the affected area gets cleaned physically first, then disinfected. This sequence matters: disinfectants work best on clean surfaces, and applying disinfectant over organic residue — silt, grease, biological material — dramatically reduces efficacy. We scrub the surfaces, rinse, then apply an EPA-registered disinfectant at the correct dwell time. The dwell time is not a detail. Most disinfectant labels specify a contact time of one to ten minutes at the listed dilution, and wiping it off immediately, which is a common shortcut, means the product never reaches its rated kill effectiveness. We apply, wait, and verify before we consider a surface treated.
Concrete floors and walls get particular attention because concrete is porous. We apply disinfectant, scrub, and apply a second time to the lowest three inches of the wall where the heaviest contamination load typically is. In finished spaces where drywall on the lower wall has been removed, the exposed concrete or CMU block behind it is treated the same way.
Drying a contamination event
The drying phase of a CSO event follows the same principles as any water event but with an important additional consideration: drying equipment placed in a contaminated space is itself contaminated and has to be decontaminated before it leaves. We run air movers and dehumidification to bring the structural assemblies back to a dry standard, but the equipment is cleaned and disinfected before it goes to the next job. This is a basic professional standard that protects every subsequent customer who uses that equipment; it is worth asking any contractor who responds to your sewage event whether this is part of their procedure.
Concrete floors following a CSO event dry more slowly than wood-frame subfloors, and we meter them every day until the slab readings confirm it is genuinely at baseline. A damp concrete floor with fresh drywall installed over it is a delayed mold problem on a predictable schedule.
The insurance conversation for sewer backup events
This is one of the most important things to understand before you have this event: standard homeowner and standard renter policies typically do not cover sewer backup without a specific endorsement. Flood coverage is a separate policy. Many Union City and Hudson County residents are underinsured for exactly this type of loss, which is one of the most common water-damage events in the area. If you have not looked at your policy recently to verify whether you have a sewer backup or water backup rider, this is the moment to do it.
For building owners and commercial tenants who do have the coverage, the documentation we produce — extraction records, material removal scope, photo log, disinfection protocol, and drying readings — gives the adjuster a complete, professionally produced file. The contamination category is documented, the removal scope is justified, and the disinfection is proven. This level of file typically moves through the claim review faster than a verbal account of what happened.
Prevention: what actually helps
You cannot stop a combined sewer overflow from happening, but you can reduce the likelihood that it surfaces in your basement. A backwater valve, also called a check valve or sewer check valve, is installed on the building lateral inside the basement and allows flow only in one direction — away from the building. When the main backs up, the valve closes, and the overflow cannot enter the basement through that lateral. These are not universally present in Union City's older building stock; many were built before the technology was standard, and retrofitting them requires accessing the drain lateral and installing the valve under the floor slab.
A properly installed backwater valve eliminates almost all sewer-backup risk from combined overflow events. It does not help with water that enters through foundation cracks, which is a different problem requiring waterproofing, but for the drain-origin backup that is the most common CSO pathway, it is highly effective. Hudson County's municipal offices and the state have at various times offered rebate programs for backwater valve installation; it is worth checking whether a current program is in effect when you are budgeting this improvement.
After the event: monitoring for secondary effects
Once the space has been cleaned, disinfected, and dried to a confirmed standard, the job is not entirely done. In the weeks that follow a category 3 event, keep a periodic eye on the affected areas — particularly at floor-wall junctions and behind any remaining furnishings — for signs of mold growth that the initial response missed. The risk is lower in a properly completed remediation, but conditions on the day of cleanup, including humidity, temperature, and the speed at which materials were removed, all affect how thoroughly the colonization risk was eliminated. If a musty smell returns, that is the signal to call before it becomes visible.
We also recommend that building owners document the event in the building maintenance log with the date, flood depth, and the remediation company contact information. Hudson County has experienced multiple CSO events at some addresses in the same building in successive years, and a maintenance record that shows the history supports both the insurance relationship and the case for permanent backwater valve installation as a capital improvement.
For any sewage or combined sewer overflow event in Union City or Hudson County, call Silva Water Damage CO at 551-351-9712. We respond around the clock, treat every backup as the category 3 event it is, and produce the documentation your claim requires. If the rebuild that follows the remediation includes drywall and flooring, our reconstruction crew is the same company, same timeline, and the same documented scope from start to finish.