Parson Manhole Insert

Parson Manhole Inserts are manufactured from high-density, high-molecular-weight polyethylene and are proven effective to reduce and prevent excessive surface water inflow entering the collection system through the manhole lid. Inflow caused by heavy rainfall is significantly reduced, lowering plant operating and treatment costs. Parson Manhole Inserts are a practical solution to expensive plant expansions and high sewage treatment costs.


  • No-valve method of ventilation available
  • Single or double-valve ventilation system available
  • No corrosive parts
  • No maintenance required
  • Keeps grit, sand, salt, chemical spills, foreign objects, road oils, etc. from entering collection systems
  • Cost-effective alternative to replacing existing manhole covers with “watertight” covers

A factory-installed, closed-cell neoprene or cross-linked polyethylene gasket is available upon request.


Proven to significantly reduce stormwater inflow and additional treatment costs, Parson inserts are manufactured to customer specs. They are easy to install and remove, highly durable, and maintenance-free.

The Parson Manhole Advantages

• Made from corrosion-resistant materials

• Easy to install and remove

• Little to no maintenance

• Extends service life of manholes