Manhole System

A manhole (alternatively utility hole, cable chamber, maintenance hole, inspection chamber, access chamber, sewer hole or confined space) is the top opening to an underground utility vault used to house an access point for making connections, inspection, valve adjustments or performing maintenance on underground and buried public utility and other services including sewers, telephone,electricity, storm drains, district heating and gas.

The Millars watertight Perfect Manhole System is a precast off-site solution which enables contractors to install a modular water tight manhole without the need for a concrete surround.

This quick assembly system comprises of a monolithic precast concrete base pre-benched to any inlet / outlet configuration, together with thick walled chamber rings with water tight joints incorporating an elastomeric gasket and a sealed cover slab. The system also incorporates push fit elastometric seals for inlet and outlet pipes.

Specifiers, designers and contractors can be assured that the Millars Perfect Manhole System offers a safer, faster, sustainable, off-site bespoke manhole solution.

Superior Technology

Superior Technology
Installation is Easy

Precast concrete manholes have become the construction industry’s product of choice over cast-in-place concrete, brick and other non-concrete products for many reasons, not the least of which is ease of installation. Precast concrete manholes can be easily installed on demand and immediately backfilled. There is no need to wait for concrete or mortar to cure at the job site. The degree of soil compaction around the manhole and remaining trenches is never a problem, making installation faster and easier. Contractors are familiar with how to handle precast concrete manholes and can easily install them. Standard sealants and flexible joints are readily available and are vital to water tightness.


Because precast concrete products typically are made in a controlled environment, they exhibit high quality and uniformity. Variables affecting quality typically found on a job site temperature, curing conditions, material quality and craftsmanship are nearly eliminated in a precast plant.

1. Recycling

Precast plants reuse formwork, in itself a conservationist practice. Offsite casting significantly reduces construction waste that would otherwise be generated on the job site. In addition, cementitious materials used in concrete often contain manufacturing by products such as fly ash and blast furnace slag that would otherwise find their way to a landfill. Wastewater at the plant can be recycled for use in manufacturing. Steel used for concrete reinforcement is typically comprised of 95% post-consumer recycled content.

2. Reduced Site Impact

Since precast concrete manholes are manufactured off site and delivered on demand, there is a significant reduction in truck traffic, dust, noise and debris from formwork associated with poured-in-place products. Because precast concrete manhole components are modular and standardized, they are installed in a quicker fashion and also result in reduced construction times and energy usage, less noise and fewer emissions from on-site equipment.

3. Durability

Concrete is a very strong and durable material, which is a significant sustainable attribute. It will not rust, rot or burn and has a service life of in excess of 100 years.

4. Nasty Weather? No Problem

Precast concrete increases efficiency, because weather will not delay production of the manholes. In addition, weather conditions at the job site do not significantly affect the schedule, because less time is required to install precast compared with other construction materials, such as cast-in place concrete or brick.

5. Watertight – Darn Right

Standard watertight sealants and gaskets are available that are specially designed for use with precast concrete, making multiple-seam precast concrete manholes very easy to construct. Vacuum testing is an easy means of verifying water tightness, either in the plant or in the field.

6. Rough, Tough and Long-Lasting

Precast concrete strengthens with time, while other materials can deteriorate, experience creep and stress relaxation.

7. Will Sit Tight Without Tie-Downs

With a specific gravity of 2.40 and superior frictional resistance, precast concrete manholes resist buoyant forces better than all other manhole materials. Fiberglass has a specific gravity of 1.86 and HDPE has a specific gravity of 0.97, requiring the use of tie downs and ultimately increasing project costs and installation headaches.

Manhole Design


Precast Manhole System

  • Base
  • Transition Plates
  • Risers
  • Cone section
  • Adjusting Rings
  • Manhole cover Frames
  • House connections
  • Gully gratings