Stop paying to treat rainwater.
Reduce inflow at the cover. Vent safely.
Well‑ventilated gases prevent corrosive buildup and safety risks. Sewer Sentry replaces the cover with a patented system that reduces inflow while still venting H₂S safely.
Our technology: Sealed holes + valve-reduced inflow limit rain entry.
Available in both Cast Iron and Composite manhold covers.
Available in the following manhole lid sizes: 24 Inch, 26 Inch, 32 Inch.
Available in 4-inch and 7-inch heights.
The Sewer Sentry riser is available in Nylon 66 and Stainless.
All Sewer Sentry manhole cover gaskets are fitted with a 1” wide, 1/8” rubber seal that helps create minimal leakage between the sewer hole cover and bearing surface. The Sewer Sentry sewer solution system is installed through a hole that is drilled in the manhole cover using a rubber gasket to minimize leakage. It protrudes approximately 5/8” above the surface of the manhole cover, allowing some sheet flow over the cover but not high enough to damage bicycles, vehicles, etc.
The Sewer Sentry Manhole Vent Device was independently tested for compression strength with a minimum 6000 lbs. with no cracking or deformation. Sewer Sentry is offered in stainless steel, and DuPontTM Zytel® ST801-NC010A, a nylon 66 resin that is highly impact-resistant, chemical, UV, and heat/cold resistant.
The sewer sentry is installed with a rubber gasket constructed of commercial-grade EPDM (Ethylene Propylene Diene Monomer) blended rubber in 60 durometer (a measure of hardness).
EPDM provides superior properties for outdoor and high-temperature applications, with a minimum of 1000 PSI tensile strength, accommodating temperatures from -20 to 230 degrees F, provides resistance to ozone and many oxidizing chemicals and acids, and is highly resistant to sunlight.
US Patent 8,851,781 B1
Prevent rainwater from entering manholes with the Sewer Sentry System, a patented technology designed to reduce inflow during storms and protect sewer systems from corrosive gases. The innovative design features a riser with a ball check valve that prevents backups and costly stormwater treatment, while allowing harmful gases to safely vent. Compression-tested and DOTD-approved, the Sewer Sentry ensures durability and reliability.
The Sewer Sentry device stops storm water from going through hole in the manhole cover simply by creating a new point of entry ―a “raised hole”―that is 5/8” higher than the surface of the manhole. At the same time, it reduces sewer gas problems, by allowing enough oxygen to reach the sewer.
With a standard manhole, heavy rain inflow leads to more water in the storm drain and sewer that needs to be processed thus overwhelming the pumps.
With the Sewer Sentry manhole, the rain water is correctly diverted to the storm drain, allowing the system to breathe properly and not overwhelming the pumps.
Available in both Cast Iron and Composite manhold covers.
Available in the following manhole lid sizes: 24 Inch, 26 Inch, 32 Inch.
Available in 4-inch and 7-inch heights.
The Sewer Sentry riser is available in Nylon 66 and Stainless.
All Sewer Sentry manhole cover gaskets are fitted with a 1” wide, 1/8” rubber seal that helps create minimal leakage between the sewer hole cover and bearing surface. The Sewer Sentry sewer solution system is installed through a hole that is drilled in the manhole cover using a rubber gasket to minimize leakage. It protrudes approximately 5/8” above the surface of the manhole cover, allowing some sheet flow over the cover but not high enough to damage bicycles, vehicles, etc.
The Sewer Sentry Manhole Vent Device was independently tested for compression strength with a minimum 6000 lbs. with no cracking or deformation. Sewer Sentry is offered in stainless steel, and DuPontTM Zytel® ST801-NC010A, a nylon 66 resin that is highly impact-resistant, chemical, UV, and heat/cold resistant.
The sewer sentry is installed with a rubber gasket constructed of commercial-grade EPDM (Ethylene Propylene Diene Monomer) blended rubber in 60 durometer (a measure of hardness).
EPDM provides superior properties for outdoor and high-temperature applications, with a minimum of 1000 PSI tensile strength, accommodating temperatures from -20 to 230 degrees F, provides resistance to ozone and many oxidizing chemicals and acids, and is highly resistant to sunlight.
US Patent 8,851,781 B1
Introducing oxygen into sewer systems can effectively reduce hydrogen sulfide (H₂S) levels by creating aerobic conditions that inhibit the activity of sulfate-reducing bacteria responsible for H₂S production. This approach has been successfully implemented in various cases. For instance, in Milford, Connecticut, an oxygen injection system was installed to address severe sewer collapse and high H₂S concentrations exceeding 50 ppm in lift stations. The implementation of this system led to the elimination of H₂S-related issues.
Example of cost to implement for a 1MGD System:
Capital Cost: $150K-500K
Oxygen Supply: $5K-8K
Energy & Maintenance $10K-20K
H₂S is one of the most damaging and costly byproducts in wastewater collection systems.
Left unmanaged, H₂S leads to chemical and structural deterioration, public complaints, and safety risks.
Sentry Retrofit requires utilizes existing frame with drop in gasket and new Sewer Sentry Cover. Minimal traffic disruptions, no permits needed.
Sewer Sentry replaces the cover with a patented system that reduces inflow while still venting H₂S safely.
The Sewer Sentry System is an innovative, patented inflow reduction technology solution that dramatically reduces inflow during rainstorms and lowers a sewer system exposure to corrosive gasses.
The Sewer Sentry Riser is ⅝” high, so water goes around the vent hole. If the water rises higher, a ball check valve prevents the rainwater from entering the manhole. This eliminates extra electricity and water treatment costs at the pump stations, prevents storm water backups into homes and businesses, and allows harmful odors to escape.
The Sewer Sentry Manhole Device is Department of Transportation and Development Approved, ensuring reliability and safety for municipal systems. It has been compression tested to ASTM D4280-12 standards, successfully withstanding 6000 lbs of pressure in three directions without cracking or deformation, demonstrating its durability for public infrastructure use.
The Sewer Sentry manhole is designed for easy installation, making it a popular choice for over 26 cities that are already benefiting from its reliable performance. Cities that have implemented this solution are enjoying improved sewer inflow management, reducing flooding risks, and lowering maintenance costs.
Exposure to Pathogens: Untreated sewage contains harmful bacteria, viruses, and parasites that can cause diseases in humans, such as gastrointestinal illnesses, hepatitis, and skin infections.
Contaminated drinking water: Sewage overflows can contaminate water sources, posing serious health risks to communities that rely on these sources for drinking water.
Water pollution: Sewage overflows introduce pollutants, such as nutrients, chemicals, and heavy metals, into rivers, lakes, and oceans, leading to water quality degradation.
Clean-Up and repairs: Municipalities incur significant costs for cleaning up contaminated areas and repairing damaged infrastructure.
A Sewer Sentry kit was installed through a hole that is drilled into the manhole cover using a rubber gasket to minimize leakage. It creates a raised vent hole approximately 5/8″ tall at its highest point.
This system can now “breathe” without allowing water to flow into the vent hole. Water flows around the vent hole instead of in it. The sewer gases will also not accumulate and create sewer gas problems with the sewer system.
A rubber gasket was glued to the manhole ring to prevent the water from entering between the ring and cover. This completes the install of the Sewer Sentry system on the manhole.
If water goes over the 5/8″ high Sewer Sentry in heavy rains, a Sewer Sentry check valve can also be easily installed underneath the Sewer Sentry.
It dramatically reduces the inflow during rainstorms, and with the red dye, the water is seen flowing past the manhole to the storm water system where it belongs.
Louisiana Tech’s Trenchless Technology Center completed an independent study of the Sewer Sentry and measured an inflow reduction of up to 98%!
By reducing wear & tear of pumps and doubling or tripling your pumps’ lives.
By preventing sewage from overflowing into our beaches, waterways, and streets where we live our lives.
In this video, a new manhole cover was just installed with no vent holes. Vent holes would create even more inflow during rainstorms, and the water from this water hose is simulating rainwater entering the sewer lid.
The Sewer Sentry System allows your system to breathe, creating a healthier system and fewer complaints about smell by preventing reducing the production of sewer gas and the accumulation of sewer gas.
The red food dye shows the flow of water better, and it’s easy to see how water from the water hose is still entering the sewer system with the manhole lid shut.
Remember, this is a brand new manhole ring and cover. An older manhole would allow even more inflow.
Don't just take our word on why you should choose Sewer Sentry. See what our customers have to say about our combined sewer overflow solutions!
We’ve gathered answers to the most common questions we receive about Sewer Sentry. Click on any question below to explore more and discover how our solutions can help improve your wastewater system.
A sanitary sewer overflow (or SSO) occurs when the sewer system becomes overwhelmed by additional water. Normally, sanitary sewers are designed to handle wastewater from homes and businesses, but during rainstorms, extra water from rain can enter the system.
This extra water can come from manhole covers, open or broken cleanouts, and roof gutters tied to sewer service where rainwater gets into the sewer system. When the amount of water exceeds the capacity of the sewer system, it causes the sewage to overflow, leading to spills into the environment.
Rainstorms overwhelm sanitary sewer systems quickly due to the sudden surge in water entering the system. Normally, the system is designed to handle a steady flow of wastewater from homes and businesses.
However, during a rainstorm or storm surges from a hurricane, a large amount of water can enter the system at a much faster rate than the system can hold. This quick influx of water exceeds the system’s capacity, leading to overflows and spills onto beaches, waterways, and on the streets.
The Sewer Sentry System is a patented, engineered solution that replaces standard manhole rings and covers with specially designed components that block rainwater inflow and help prevent sewage overflows. By stopping excess water at the source, the system reduces strain on sewer infrastructure and lowers the risk of backups and flooding.
The Sewer Sentry System is built for long-term durability. It has been rigorously compression tested in accordance with ASTM D4280-12 standards and can withstand 6,000 pounds of load in multiple directions without cracking or deforming. This ensures reliable performance under real-world traffic and infrastructure conditions.
The System dramatically reduces inflow during rainstorms, lowering the sewer system’s exposure to corrosive gases. This efficient management of sewage overflow eliminates unnecessary costs at the pump stations and reduces environmental pollution caused by untreated sewage.
Yes, the Sewer Sentry Riser is designed to allow harmful gases to vent, making it safe. If the water level rises, a ball check valve prevents the rainwater from entering the manhole.
The Sewer Sentry System is available in sizes of 24 Inch, 26 Inch, and 32 Inch, with heights of 4 Inch and 7 Inch.
Inflow during rainstorms
Inflow during rainstorms adds significant cost to wastewater processing at treatment plants, such as electrical, treatment, wear and tear of pumps. It also may create sanitary sewer overflows (SSOs), leading to possible DEO & EPA fines, consent decrees from the EPA, or the flooding of homes & businesses, which can bring costly lawsuits.
Sewer Gases
Sewer systems need to “breathe,” both into. the system and out of the system. When not enough oxygen reaches the sewer, hydrogen sulfide forms, causing the rotten eggs smell. Too much build-up of sewer gasses can a result in a fast deterioration to your sewer system, danger to employees, health issues, or even an explosion.
Sewer Sentry prevents excess stormwater from entering sewer systems, reducing the likelihood of overflows during heavy rain events. By stopping inflow at the source, the system lowers the release of harmful gases and untreated wastewater that can occur when infrastructure is overwhelmed.
As extreme weather events become more frequent, wastewater infrastructure must adapt. Sewer Sentry strengthens system resilience by limiting inflow during storms, helping municipalities reduce failure points, manage peak loads, and respond more effectively to climate-related stress on sewer networks.
By preventing rainwater, debris, and contaminants from entering the system, Sewer Sentry improves treatment efficiency and reduces unnecessary processing. This leads to lower energy use, reduced operational strain, and less waste generated across treatment facilities.
Sewer Sentry helps prevent sewage overflows that can contaminate rivers, wetlands, and coastal environments. By keeping wastewater contained and managed, the system supports the protection of freshwater resources, biodiversity, and sensitive ecosystems.
Inflow is a major contributor to sewer overflows and infrastructure failure, especially in aging systems. Addressing inflow at the source is one of the most effective ways to improve system performance, reduce environmental risk, and extend the life of existing infrastructure.
