Manhole Vacuum Tests

A manhole vacuum test is a process that uses a vacuum to identify leaks in a manhole structure by measuring the time it takes for a 10-inch mercury (Hg) vacuum to drop to 9 inches of mercury (Hg). The test involves sealing the manhole’s inlet and outlet pipes with temporary plugs and using a test head (either a flat plate or inflatable bladder) to seal the top. A vacuum pump then creates a negative pressure, and if the vacuum holds for the required time, the manhole passes; otherwise, repairs are needed.

Benefits of doing a Manhole Vacuum Test

The purpose of a manhole vacuum test is to verify the structural integrity and watertightness of a manhole before it goes into service or during maintenance checks

• Ensure there are no leaks – preventing groundwater from seeping in (infiltration) or sewage from leaking out (exfiltration).
• Protect the environment – stopping contamination of soil and groundwater.
• Reduce treatment costs – keeping excess water from entering sewer systems and overloading treatment plants.
• Confirm quality of construction/repairs – making sure joints, seals, and materials were installed correctly.
• Meet regulatory standards – most municipalities and utility companies require proof of watertightness before acceptance.