A 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 work.

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 perform an inspection or repair of the piping system, although this is not always the case. CCTV drain surveys and water jetting can be carried out via manhole chambers in order 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.

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 Look Like?

The design and depth of an inspection chamber and manhole cover largely depends 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 themselves also 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 into 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 that they are not blocked.

If you wish to build over an inspection chamber, it is essential to 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

There are two factors that will determine the maximum depths at which an inspection chamber can be installed: safety and usability.

In order for your inspection chamber to comply with building regulations, an approved chamber must be installed, and this must be at a depth where there is no risk to human life by falling into the chamber. However, the chamber must still be an effective access point for both cleaning and accessing the drainage system whenever needed.

Mini Access Chambers

Mini access chambers tend to be around 300mm in diameter. The narrow width of this type of chamber means that you can only effectively use it to a depth of up to 600mm. With this in mind, these chambers are generally only used close to the house near the top of the drain.

Standard Inspection Chambers

Standard inspection chambers are usually 450mm in diameter. These provide good access for cleaning and rodding. However, this size of inspection chamber is large enough for a child to fall into. This means that the maximum permitted installation depth for a standard chamber cover is up to 1200mm.

Inspection Chambers at Greater Depths

If you want to use an inspection chamber at a depth greater than 1.2 metres, it is possible. You can use a 450mm inspection chamber up to a depth of 3 metres. However, you will need to incorporate a chamber reducing ring to restrict the opening to just 350mm. This will reduce the opening and effectively prevent anyone from falling inside it.

It is rare for a 450mm inspection chamber to be installed to a depth greater than 1.5 metre. This is because rodding becomes much more difficult at greater depths. With this in mind, inspection chambers are typically used in modern installations as camera access points.

Inspection Chambers Within Gardens and Homes

There are certain times when the utility company is responsible for the inspection chambers and manholes. However, there are times when you are responsible for all of the drainage system elements at your home.

There are many pipes, sewers, and drains that are hidden away from view underneath your home or garden. It’s worth bearing in mind which parts you are responsible for. Below is a list of the things you’re likely to be responsible for and those that the local utility company is responsible for.

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 right up to your property boundary (unless it is 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, get in touch with us today for some advice.

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 are the small grate-covered opens that 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 in question.

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 when 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 are having 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 whole series of inspection chambers.

You can learn more about our manhole inspection services for commercial and domestic customers. Alternatively, give us a call on 0800 526 488 for more information, or fill in our online enquiry form to request a call back.

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