Which Inspection Chamber Component Do I Use and When?

Inspection chambers are crucial for testing and inspecting underground drainage and clearing any blockages.

Different inspection chamber types are more suitable for specific uses, deep or shallow placement, internal or external projects and Some chamber components are only used under specific circumstance.

So, here’s a quick guide to inspection chambers and their components, and some examples of when you might want to choose one over another.

Access Chambers

Access chambers are designed to provide simple access for inspection and equipment. They are not intended to be accessed or entered by maintenance staff, and tend not be fitted more than 600mm deep or larger than 300mm in diameter.

Inspection Chambers

Inspection chambers are slightly larger versions of access chambers, often 450mm-600mm in diameter. The main difference between access and inspection chambers is size, however inspection chambers also tend to be deeper (up to 1000mm) and tend to have more branches feeding into them.


Manholes are even larger than both access and inspection chambers. These large chambers are big enough to allow maintenance staff to enter the system itself, and manholes often lead to industrial or public sewerage systems as opposed to individual property drainage.

The minimum dimensions of manholes are 600x900mm and they’re often at least a metre deep.

Manhole covers ensure that manholes are kept sealed and blocked off from public access.

Twinwall Inspection Chambers

Twinwall inspection chambers, much like twinwall drainage, are better reinforced inspection chambers that can deal with a high flow of water. These inspection chambers are made from Polyethylene, which is stronger than PVC.

These inspection chambers are designed to fit with all of our twinwall and standard drainage pipes, and will allow for testing, inspection, maintenance and cleaning of twinwall drainage systems.

Foul and Surface Chambers

These inspection chambers are used solely to transport waste water from sewage. Some homes, especially newer homes, will have dual systems where foul and surface water are carried together in the same pipes, and this is where you would install these inspection chambers. They’re wide in diameter and depth in order to allow for any contaminants that may come with waste water to pass through easily.

Yard Gullies

Yard Gullies are used to trap and separate surface water. They can eliminate silt from entering the drains.

Yard gullies are excellent if you’re looking to prevent any blockages in your drainage system.

Our yard gullies are trapped, which means they will prevent any drain odours from escaping the drainage system.

Catchpit Chambers

Catchpit chambers are empty chambers installed to catch silt and debris from the system, and to prevent this entering a soakaway or other drainage components which could lead to clogging and blocking of the system.

It’s important to clean catchpit chambers regularly due to the fact their sole purpose is to catch debris – you will soon see this pile up.

Whatever project you’re completing, there’s bound to be the right inspection chamber for you, however this guide will help you to determine which might be more suitable for the specific use you’re intending.