Inspection chambers and manholes in a UK garden or drive

A square or round cover in a garden path or a driveway usually sits over a drain. Lifting it can tell you a lot when a toilet will not flush or a gully is backing up. It can also be heavy, dirty and dangerous. This page helps you work out whose cover it is, when a quick look is reasonable, and when to leave it alone.

Do not enter a chamber. Not even a shallow one, and not to reach a blockage. Drains can hold gases and too little air to breathe, and a chamber can be deeper than it looks.

Inspection chamber or manhole?

The words are used loosely, but there is a useful difference.

An inspection chamber is a shallow access point on a private drain. It lets someone look along the pipes and rod them. In a typical house there may be one near the back door, one where drains join, and one near the boundary. Covers are often plastic or light steel.

A manhole is deeper, usually large enough for a person to go down with the right training and equipment. Manholes on public sewers are often in the road or pavement, and sometimes in gardens where a shared sewer crosses private land. Covers are usually heavy cast iron.

Not every cover is a drain. Some are for water company valves, gas, electricity, telecoms or cable TV. Some are for surface water rather than foul drainage. Thames Water's manhole covers page shows the range of covers in its area, and says responsibility depends on type and location.

Who looks after it

CCW's page on drains and sewers says homeowners are responsible for drains that serve their property and lie beneath the property, garden or driveway. Wastewater companies are responsible for main sewers, and for shared pipework that connects to a public sewer. For problems within the boundary, CCW suggests a plumber or an independent drain clearing company. If you are not sure whose it is, it suggests contacting your sewerage provider and keeping a record of the contact.

Thames Water's page says that, in its area, wastewater access covers inside your property boundary are yours to maintain, that it will confirm responsibility if a cover serves other properties too, and that it is responsible for wastewater manholes outside property boundaries. That is one company's statement for its own area. Do not treat one water company's area as a national rule; check your own sewerage company's pages. Scotland and Northern Ireland have their own water and sewerage bodies and their own arrangements.

When lifting a light private cover is reasonable

If the cover is plainly on your own drain, is light, has a lifting point or handles, and is not cracked, you can usually lift it to look. Before you do:

• Wear gloves and stout shoes. Keep children and pets away.
• Use the lifting keys or handles meant for it. Do not lever with a screwdriver.
• Lift with your legs and slide the cover aside rather than carrying it.
• Do not lean in, kneel over the opening or put your head below ground level.

Then look. A chamber with water standing in it is downstream of the blockage. A dry chamber with a full one upstream tells you the blockage is between them. That is useful to tell a drainage firm, along with which fittings in the house are slow. If everything is clear in your chambers but the house still backs up, the problem may be in a shared drain or the sewer.

Put the cover back as soon as you have looked, and make sure it sits flat. An open chamber is a fall hazard.

When to stop

Leave the cover and call a drainage firm, or your sewerage company, if:

• the cover is heavy cast iron, rusted in, cracked or set in a road or pavement;
• you are not sure the cover is on your drain, or it serves neighbours too;
• sewage is coming out of the chamber or out of a neighbour's;
• the chamber is deep or you cannot see the bottom;
• there is a strong smell of gas or sewage;
• the pipes look broken or roots are visible.

A blockage you can see is still a job for drain rods or a jetter, worked from the surface by someone who knows how. Do not pour chemicals into a chamber. If the toilet or sink is the only thing backing up, start with blocked toilet or blocked sink. A smell with no blockage is covered in drain smells. The wider picture, including gullies and soakaways, is in outside drains.

Covers in driveways

A light garden cover is not made to carry a car. If you are laying a new drive over a chamber, ask the builder about a cover rated for vehicles. A cover that rocks or sinks under a car can break, and a broken cover over a deep chamber is dangerous. Report any damaged public cover to whoever is responsible for it. For a road gully, that is often the highway authority rather than the water company.

Can I go down into a manhole to clear a blockage?

No. Do not enter a chamber or a manhole. They can contain harmful gases and too little oxygen. A drainage firm can clear blockages from the surface, and the sewerage company deals with its own sewers.

Whose responsibility is the manhole in my garden?

It depends on what it serves. CCW says homeowners look after drains serving only their property within the boundary, and wastewater companies look after shared pipework and main sewers. Check your own sewerage company's guidance, because arrangements are not the same everywhere.

What if the cover is too heavy to lift?

Leave it. A heavy or stuck cover needs the right lifting equipment. Call a drainage firm, or the sewerage company if the cover may be theirs.