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safe and secure


The Stainless Steel Rainstopper is a patented manhole insert designed to eliminate inflow in your municipality’s sanitary sewer system. Along with mitigating sanitary sewer overflow, it also reduces the infiltration of street level contaminants, while simultaneously controlling the escape of undesirable sewage odor and minimizing traffic related manhole noise and cover displacement. The insert is manufactured in the USA to precise, custom specifications from corrosion resistant 304 or 316 stainless steel. Its unique design allows the venting of sewer gases through a non-mechanical device, reducing maintenance costs by eliminating moving parts. Weighing only 10 pounds, it can be easily installed by a single person. 


Developed to ensure against loss or theft, the TETHERLOK system employs a five-foot length of 3/16" braided stainless steel cable—resistant to common bolt cutters—with cable terminals and eye ends crafted in stainless steel. The cable is secured to the insert with a stainless steel rivet and secured to the manhole frame via drive pin.


Accurate frame and cover measurements are absolutely critical for the successful elimination of inflow. While carefully following the instructions included on the Rainstopper Measurement Worksheet (PDF 244 KB) measure and record the physical dimensions for each unique manhole  frame and cover. Enter the desired quality for each measurement configuration. Do not hesitate to contact us if you have questions or concerns.


Long term exposure to UV rays can deteriorate the gasket, so care should be taken to protect the stored units prior to installation. Manufacturer recommends either leaving polyethylene shrink wrapped units on pallets if stored outside or storing unpackaged units in an area protected from direct sunlight.


To install the Rainstopper insert, follow these steps. 

  1. Remove the manhole cover.

  2. Clean all dirt and debris from manhole frame.

  3. Seat the insert in manhole frame rim to insure fit.

  4. Remove insert

  5. Drill 1/4"hole 7/8" deep into the frame, 1" below the bottom of seat lip and 2 1/2" above the bottom of the frame. See image below.

  6. Place drive pin through eye hole at end of tether.

  7. With drive pin in 1/4" hole, drive pin until eye and head of pin are flush with frame wall.

  8. Jerk tether to insure proper engagement of drive pin and hole.

    • If tether is not secure, hammer drive pin more securely into wall.

    • If pin is loose enough to pull out, re-drill hole.

  9. Seat the insert in manhole frame.

  10. Replace manhole lid.

  11. Ensure lid is flush with frame to alleviate tripping hazard. Once installed, maintenance is not required.

TETHERLOK Detail.png


Limited fifteen-year replacement warranty: If insert is defective in materials or workmanship within fifteen years of purchase, it will be replaced free of charge by Rainstopper if not damaged through mishandling, accident, or abnormal use, and excludes replacement of handle, valve, and gasket.

Data Sheet (PDF 298 KB)

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