The Ultimate Guide to Inspection Chambers and Manholes
Inspection chambers, also known as manholes, are an important part of any drainage system. These access points allow drainage professionals to inspect and survey drainage infrastructure and perform essential repairs and cleaning.
The installation and maintenance of inspection chambers are crucial to keeping domestic and commercial drains in perfect working order, which is why property owners and residents need to understand how they work and what is required to keep them well-maintained.
What is an Inspection Chamber (Manhole)?
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 and manhole cover largely depend on the depth, size and type of pipe it is accessing.
Some manhole chambers are only a few feet deep, making it possible to see the pipe inside when the cover is removed; in other cases, they may lead to much deeper drains and sewers located many metres underground, meaning steel ladders are required on one side of the chamber to provide access.
The manhole covers vary in shape and size depending on the type of pipe and the area in which they are located.
Larger, thicker and more robust covers are needed in locations where traffic or heavy vehicles regularly pass over the top of the chamber. In contrast, a steel security grill may protect larger access points to prevent unauthorised access and stop items from being dropped down the drain.
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 are easily accessible and not blocked.
If you wish to build over an inspection chamber, you must check whether you have permission to do so. In many cases, it may be necessary to move the chamber, have the pipes diverted or change the building plans to maintain access to the existing manhole.
Inspection Chamber Regulations
Two factors determine the maximum depths at which an inspection chamber can be installed: safety and usability.
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?
When it comes to drainage systems, it's important to know who is responsible for what. The utility company is in charge of inspecting certain chambers and manholes, but as a homeowner, you also have responsibilities for parts of your drainage system.
Many pipes, sewers, and drains are hidden beneath your home or in your garden. Understanding which components you are responsible for is important.
Below is a breakdown of what you are likely responsible for and what falls under the utility company's duties
What Am I Responsible For?
You are responsible for all of the drains, pipes and gutters around your home. This includes drains from your property up to your property boundary (unless shared with various other neighbouring properties). You are also responsible for all of the inspection chambers and manholes that exist within your property grounds. If you are unsure of your responsibilities, you can read our article ‘Blocked sewer drains: Who is responsible?’ for more information.
What Is the Local Utilities Company Responsible For?
Your local utilities company is responsible for the large public sewers that take sewage and rainwater off to the local wastewater treatment works. They are also responsible for all of the pipes from the edge of your property boundary, right the way up to where they connect to the public sewer. Shared drains (where the drains of several properties meet before joining the public sewer) are also the responsibility of the local utilities company.
What is Your Local Authority Responsible For?
The local authority is responsible for road gullies. These small grate-covered opens are used for draining surface water and can be found at the edge of 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. Mechanical cleaning methods using high-pressure water and suction have been the preferred approach for cleaning manhole chambers for over 30 years. This kind of work can only be done by a trained professional.
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 – as such, cleaning and repairs should always be handled by a qualified engineer with experience working in confined spaces.
If you have an issue with the manholes on your property, Lanes Drainage Services UK can provide the support you require. 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.