The Ultimate Guide to Inspection Chambers and Manholes
17/04/2024
Inspection chambers, also known as manholes, are access points built into underground drainage systems that allow drains and sewers to be inspected, cleaned and repaired.
They are a legal requirement under UK Building Regulations, as they are needed to keep drainage systems working safely and efficiently.
All drainage systems must have adequate access points to allow for the inspection and maintenance of domestic and commercial drains.
Property owners and residents need to understand how they work and what is required of them in terms of maintenance and for property protection.
In this article, the team at Lanes explains what inspection chambers are, where they are located, the different types used in the UK, who is responsible for them, and how they should be safely maintained.
What is an Inspection Chamber (Manhole) and where are they located?
An inspection chamber is a sectional entry point that typically consists of a base, sealed sectional risers and a manhole cover made of steel, brick, concrete or plastic.
They are situated along the length of the drainage system and are most typically found at key intersections, such as where:
- A branch drain joins the system’s main drainage pipe
- There is a straight run of piping extending more than 22 metres
- A drain or sewer pipe changes direction horizontally by more than 30 degrees
- There is a change in pipe size
Inspection chambers are usually designed to be large enough to allow a person to climb inside to inspect or repair the piping system, although this is not always the case. CCTV drain surveys and water jetting can be carried out via manhole chambers to remove blockages.
In some cases, manholes incorporate smaller remote access drainage points or rodding points, which provide access for a drain rod, water jetting hose or a CCTV camera to be inserted without anyone needing to enter the chamber physically. Discover our CCTV surveying services by visiting our dedicated CCTV Survey page online.
The design, location and structure of manhole and inspection chambers are governed by UK Building Regulations, which should be consulted before installing an access point.
What Does an Inspection Chamber (Manhole) Look Like?
The design and depth of an inspection chamber depends on the type of drain it serves and the area in which it is located. In areas with heavy traffic and vehicles, thicker and more robust covers are used to allow them to regularly pass over the top of the chamber. In other locations, steel security grills may be installed to protect larger access points from debris and to prevent unauthorised access.
What is the Purpose of Inspection Chambers and Manholes?
Inspection chambers are essential parts of a property’s drainage infrastructure and serve several key functions:
- They allow drains to be cleaned, cleared and inspected as and when required
- They prevent unauthorised individuals without proper qualifications from entering the drainage system
- They work as a temporary storage point for water, allowing excess liquid to build up in the drainage system rather than flooding out immediately
As such, it is vital to ensure that inspection chambers and manholes remain accessible and unobstructed at all times.
Can you build over an inspection chamber?
In many cases, you can not build directly over an inspection chamber, but with approval, you might be able to move the chamber, have the pipes diverted, or modify the building plans to maintain access to the existing manhole.
If you wish to build over an inspection chamber, you must obtain permission before work begins. You may be able to get formal approval from your water supplier to relocate the chamber or reroute pipes with a build-over agreement.
Discover more information on build over agreements in our article ‘What is a build over agreement’.
Inspection Chamber Regulations
Inspection chambers in the UK are governed by Building Regulations Part H, which covers drainage and waste disposal. Two factors determine the maximum depths at which an inspection chamber can be installed:
- Safety - minimising the risk of falls or collapse
- Usability - ensuring the chamber remains accessible for maintenance
To comply with building regulations, you must install an approved chamber at a depth that minimises the risk of anyone falling in. At the same time, the chamber should remain accessible for cleaning and maintenance of the drainage system whenever necessary.
Discover more about the rules for building near inspection chambers and how to get planning approval in our article ‘How close can you build to an inspection chamber?’
What are the Different Types of Inspection Chambers?
Mini Access Chambers
- Typically around 300mm in diameter
- Suitable for depths up to 600mm
- Primarily used close to the house near the top of the drain
Standard Inspection Chambers
- Usually 450mm in diameter
- Provides good access for cleaning and rodding
- Maximum installation depth is up to 1200mm
Inspection Chambers at Greater Depths
- Can be used at depths greater than 1.2 metres
- 450mm chamber can be used up to 3 metres with a reducing ring to limit the opening to 350mm
- Rare to install a 450mm chamber deeper than 1.5 metres due to difficulties with rodding
- Typically used for camera access in modern installations
Who is Responsible for Inspection Chambers?
Responsibility for inspection chambers depends on their location and function.
Below is a breakdown of what property owners are responsible for and what falls under the utility company's or local authority’s duties
What Are Homeowners Responsible For?
Homeowners are typically responsible for:
- Drains and pipes within your property boundary
- Inspection chambers located on your land
- Private drains that serve only your property
If you are unsure of your responsibilities, you can read our article ‘Blocked sewer drains: Who is responsible?’ for more information.
What Are Utilities Companies Responsible For?
Your local water and sewerage company is responsible for:
- Public sewers
- Shared drains serving multiple properties
- Pipes beyond your property boundary
What Are Local Authorities Responsible For?
Your local water and sewerage company is responsible for:
- Road gullies and surface water drainage on public roads
If you are worried about blockages or smells coming from these drains, you should contact your local council so that they can inspect the problem and attend to it accordingly.
How Should Inspection Chambers Be Safely Cleaned?
If an inspection chamber becomes blocked or damaged, it can cause significant problems for the property.
An inoperable or inaccessible manhole can make it impossible to inspect or clean out a sewer or drain when necessary. At the same time, a damaged chamber or manhole cover can also lead to debris and excess water seeping into the drainage system. It could even create a risk of the chamber collapsing under a person’s weight.
In these cases, repair or replacement of the inspection chamber may be necessary, but it is important to remember that this should never be attempted manually.
The best approach uses professional equipment such as:
- High-pressure water jetting
- Vacuum and suction equipment
- CCTV inspection technology
Climbing in and out of a manhole is a dangerous task, especially considering that the chambers themselves are often full of toxic gases and low on oxygen. For this reason, cleaning and repairs should always be handled by a qualified engineer with experience working in confined spaces, such as the engineers at Lanes.
How can Lanes help
Our expert team can carry out small civil repairs when inspection chambers become damaged, using our confined entry expertise and the right resources to get the job done. We are also equally happy to work on one manhole or a series of inspection chambers.
You can learn more about our manhole inspection services for commercial and domestic customers online via our drain and manhole inspection page. Alternatively, give us a call on 0800 526 488 for more information, or fill in our online enquiry form to request a call back.