Moving a manhole: a quick guide

1 Oct

House renovations often reveal nasty or downright annoying surprises that you haven’t got a clue how to solve, and let’s be honest, you don’t want to pay for either!

So when our student Elena revealed this manhole lurking underneath her floors – we had to swoop in to write this post for you in case you’re up against the same.

Can manholes be moved? Yes.

Can you do it yourself? This one is for the pros.

Is it common? Surprisingly so.

Let’s jump into the details…

It’s not uncommon to need to move a manhole outside – or even inside – your house. A few of our Reno Club community have had to move manholes prior to building their extensions in particular. And with many projects involving plumbing or building work, it’s likely that drainage below ground will have to be moved too. It can become part and parcel of a house renovation.

Renovating a house step by step can be a minefield, but we’re here to help! In this guide, we will walk you through the main steps to take before, during and after moving a manhole. We will cover things to look out for and best practices to ensure your renovation is a success.

If you’re new here, consider downloading our free renovation guide covering ways to make cost savings on your project, and the order to do everything in to prevent rework – we specialise in supporting first time renovators :)

Step 1 - Identify and locate all sewer information.

Before you plan or undertake any work to the manhole, make sure you properly understand how the sewage works from your property. This includes the location and direction of any SVP pipes, sewer lines below ground, other manholes and connections to the public sewer.

If you have any doubts regarding this information, here are some tips to helps you:

Large vertical pipes which measure 110mm in diameter are called SVPs, these will often penetrate below ground and form the sewer directly to the nearest manhole.
Review your sewer map provided to you as part of the buyers documentation for the property. If this hasn’t been provided, request a sewer map from your water provider.
If the above information does not provide a clear location for the sewer and manholes, consider a CCTV survey of your drains.

Step 2 - Check whether your manhole is private or public.

Now that you have located the manhole and sewer lines, it is important to find out whether the manhole is only serving your property or whether it connects with other properties.

If your manhole only serves your property:

Excellent! you can move onto planning how to move the manhole.

If your manhole connects with neighbours and forms part of a public sewer:

You will need to contact your local water supplier, normally you will have to apply for a build near or over public sewer, it will also be important that your neighbours are notified when the work is planned to take place.
If you are planning additional work such as an extension, it is important to make sure the building footprint either passes over or sits 500mm away from the public sewer.

Plan your extension with complete confidence and avoid costs spiralling

Neil and Fi have produced a free 3 day email series to help new renovators feel clued up and confident before they begin their renovation work. Learn:

How to cut costs and prevent your budgets spiralling
How to find trustworthy contractors who’ll deliver on time
What order to do work in (to prevent costly rework!)

Start preparing for your project ››

Step 3 - Where can I move my manhole to?

When moving a manhole, it is important to relocate the manhole to a location which is easy to access outside of the building.

When relocating your manhole, make sure to:

Run a straight sewer run to and from the manhole.
Keep the manhole at least 500mm away from any buildings.
Make sure the manhole and connecting sewer do not interfere with any other servicing below ground.

Step 4 - Burying a manhole

It is normally advised that any existing manholes are maintained where possible. However if you do require to bury a manhole, ensure the relocated manhole provides similar or better access.

Burying a manhole is work that you should leave to a building contractor or use a specialist product for, ensuring that it is hidden but accessible.

Step 5 - How to build a manhole.

A manhole in the UK is normally built from a concrete base, brick masonry walls with a metal manhole cover at the top. The basic steps for building a manhole are:

Excavate the ground in the specified position (making sure no connecting sewage appliances are in use.)
Bed the concrete slab - making sure the sewer channel is formed within the concrete.
Build the masonry brick walls up to ground level.
Fit the manhole cover on top of the brickwork.

There are alternative off the shelf options available, including uPVC inspection chambers. These are normally less costly and easier to install.

Step 6 - Make sure your new manhole is checked by your building control officer

Once finished, be sure to have your manhole checked by your building control officer as part of the completion of the work. This will ensure the manhole is built correctly and approved by your local authority.

Moving a manhole - It’s all about planning

The undertaking of moving a manhole is relatively straightforward. The most important part is making sure you are following guidelines and gaining the correct approval from your water company.

We hope this guide has demystified some truths behind moving a manhole if you’re worried about this process happening in your property.

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