Sewer Sentry System

With Check Ball Valve

  • Specialized manhole ring
  • Rubber Gasket
  • Manhole Cover
  • Sewer Sentry Riser (Nylon 66 & stainless)
  • Check Ball Valve

Sewer Sentry System

With Check Ball Valve

  • Specialized manhole ring
  • Rubber Gasket
  • Manhole Cover
  • Sewer Sentry Riser (Nylon 66 & stainless)
  • Check Ball Valve


Additional information


Cast Iron


24 Inch, 26 Inch, 32 Inch


4 Inch, 7 Inch

Riser Type

Nylon 66, Stainless

The Sewer Sentry System saves money AND saves the environment

The Sewer Sentry System is a manhole cover gasket and ventilation solution that dramatically reduces inflow during rainstorms and lowers a sewer system’s exposure to corrosive gasses.

Sewer Sentry manhole covers are fitted with a rubber seal that helps create minimal leakage between the sewer hole cover and bearing surface. The Sewer Sentry Riser sits 5/8” above the surface of the manhole cover, venting the gasses and preventing rainwater from entering the sewer system.


Learn More


  • Cast Iron manhole ring
  • Cast Iron Cover with Sewer Sentry Vent
  • ASTM-A48 Class 35B Certified

Rubber On The Ring & Cover

Commercial grade EPDM (Ethylene Propylene Diene Monomer)

  • Minimum of 1000 PSI Tensile Strength
  • Accommodates Temperatures from -20 to 230 Degree F
  • Resistant To Ozone and Many Oxidizing Chemicals and Acids
  • Highly Resistant To Sunlight

Sewer Sentry Riser*

A nylon 66 resin that is:

  • Highly Impact Resistant
  • Chemical Resistant
  • UV Light Resistant
  • Heat Resistant
  • Cold Resistant

*Also available in stainless steel

Prevents rainwater from going into the manholes

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.

Allows harmful sewer gasses to vent

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.

DOTD Approved

Frequently Asked Questions

We’ve compiled a list of the questions we get asked the most often. To jump to the section you’re most interested in, simply click on one of the tabs directly below.

Aren't The Vents On Houses Enough To Ventilate The System?

Good question!

Manholes have a better chance of sucking air into the sewer system than vents on houses do because the manholes are closer to the power of the water flow and create a much stronger vacuum. (Imagine adding 50 feet of pipe to a home vacuum cleaner and the resulting dramatic loss of suction.)

Also, because gases rise to the highest level they can find, if you don’t vent manholes, you can still get gas deterioration because gases will accumulate. (Of course, manholes also need a way to stop rainwater from getting into your sewer system, which the Sewer Sentry also does.)

Can Sewer Sentry Deter Sewage Overflows Into Homes & Businesses?

Yes. Due to the reduction of inflow there is less surcharge of the system during rainstorms. This deters SSO’s as well as flooding of homes and businesses.

How Is The Sewer Sentry Different Than Other Products On The Market?

This category of products exists because every city that gets rain has problems with inflow through manhole lids. However, we have designed the Sewer Sentry to provide some benefits not seen in other products:

  • The Sewer Sentry does not have to be tethered to keep it from falling into the manhole.
  • It does not have to be removed to allow access to the manhole.
  • The Sewer Sentry does not have a pressurized valve to release gases. Instead, it provides an open hole that reduces the ability of the gas to accumulate at any time without the need for pressure build up.
  • It creates a pick hole that enables easy access.

How Much Height Does The Sewer Sentry Add To A Manhole Cover?

The Sewer Sentry adds ⅝” height to the profile of a manhole cover.

What About Manholes Above Ground With No Chance of Storm Water Going Over Them?

Above-ground manholes still need to be vented to lessen corrosion due to the presence of hydrogen sulfide gas and to lengthen the life of the sewer system by letting oxygen into the pipes.

Additionally, the inflow report* by the Neenah Foundry Company shows that even a splashing rain on a 24” manhole lid with one just 1” hole lets in 4.34 GPM.

This means that a town that has 400 manholes that are raised above ground can still expect an inflow of 416,640 more gallons of water during a four hour rainstorm. A city with 2000 manholes can expect 2,082,000 more gallons.

The more storm water you stop, the less you will pay for pumping and treatment as well as repairing flooded homes and cleaning up SSOs.

* Neenah Foundry Company, “A Report on Inflow of Surface Water through Manhole Covers,” date unknown. Accessed April 10, 2014.

What About Manholes In Low Areas That Go Underwater During Rainstorms?

The Sewer Sentry can be equipped with a brightly colored pipe however high you want to indicate the position of the manhole and to prevent storm water from entering the Sewer Sentry’s one-inch diameter hole.

What About Manholes With Bolt-On Lids To Prevent Overflows In High Profile Areas?

The Sewer Sentry can be equipped with a check valve system to prevent an overflow through the vent hole.

Compression Tested to 6000 lbs.

The Sewer Sentry Manhole Vent Device was independently tested for compression strength with a minimum 6000 lbs. with no cracking or deformation.***

What size is the Sewer Sentry?

   3 ½” wide at top

   2 ⅝” wide at bottom

   2 ⅞” high

   Rises only ⅝” above manhole cover

What material is the Sewer Sentry made of?

DuPont™ Zytel® ST801-NC010A, a nylon 66 resin that is:

   highly impact resistant

   chemical resistant

   UV light resistant

   heat resistant

   cold resistant

Also available in stainless steel

What is the rubber on the ring and cover made 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:

   minimum of 1000 PSI tensile strength

   accommodates temperatures from -20 to 230 degree F

   resistant to ozone and many oxidizing chemicals and acids

   highly resistant to sunlight

60 DURO was chosen for toughness but will still have enough softness to create an effective seal.

What is the glue made of?


This high-strength glue:

   is suitable for hot and cold environments

   does not crack or lose bond

   is environmentally friendly

   cures quickly

   offers some flexibility for repositioning

What kind of pipe is the extension pipe?

Max-Gain pultruded fiberglass tube made of isophthalic polyester resin and e-glass.

This tubing is:

   UV resistant

   corrosion resistant




Are you still not finding the answer you’re looking for?

Contact us directly and one of our team members will get back to you as soon as possible.

Testimonials & Case Studies

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!

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