How Do You Know If You Have a Collapsed Drain?

As many drainage systems are on the older side and made from earthenware pipes or sometimes even pitch fibre (more on what this is shortly), they are more susceptible to damage such as cracking or deformation. If part of your property’s drainage system is collapsing, it’s important it’s fixed as soon as possible, as the lingering water is likely to cause problems. But how do you know if you have a collapsed drain, how can you fix it, and who is responsible for fixing it? 

Collapsed drains aren’t always the easiest thing to identify, and many homeowners will only be aware of the problem once it causes other issues within the building, so it’s a good idea to act on any of the following signs as soon as you notice them.

Pitch fibre drainpipes – what are they?

Pitch fibre is another type of drainpipe that was popular between the 40s and 70s mainly because the materials were readily available, and it was cheap to make. It’s made mostly of a mixture of wood cellulose, coal tar and in some cases, asbestos (more detail on asbestos in the next section). One of the problems with pitch fibre pipework is that over time, it will deform and blister when exposed to things like fat, oil, hot water and external pressure. The good news is if you have problems with your drainpipes and they’re found to be pitch fibre, they don’t necessarily need to be replaced, there are solutions such as lining the drainpipes which can help keep them in good working order. This is another reason why it's important to get a professional to look at any drainage problems if it’s an older building.

Pitch fibre pipes and asbestos

Not all pitch fibre pipes will contain asbestos, but it was commonly used as a means to strengthen the material; usually mixed and bonded with the coal tar. If you currently have pitch fibre pipes but they are in good working order, it’s unlikely you’ll need to worry about the asbestos as it’s normally safe if left undisturbed. If you suspect there are problems with your pipes and they’re made of pitch fibre, we highly recommend you consult a professional so that if asbestos is identified, the pipes can be disposed of safely.   

Signs of a collapsed drainpipe

Damp and mould

Any new damp or mould patches can be an early sign of a collapsed drain. These patches will rise from the floor if you have any leaky or broken pipes underneath the building. Likewise, if you have drainage pipes underneath any outbuildings or sheds, it’s worth keeping an eye out for any signs of damp or mouldy areas. If it gets serious enough, you may even notice changes to the building’s structure, such as sagging floors or cracked walls.

Sewage smell

If a drainpipe has been damaged, it’s likely you’ll be able to smell sewage water on a regular basis in and around the building. Check that your drains aren’t simply clogged first, but if the problem persists after regular unblocking of any drains, get the pipes checked.

Subsidence

Subsidence is another key sign of a collapsed drain. If a pipe is leaking water into the surrounding soil, over time this can cause a visible indent in the ground. If you spot a slump in the ground, it’s important to get it checked by a professional as soon as possible to avoid any further damage to the surrounding area and nearby buildings.

TIP: it’s likely to be harder to spot a collapsed drain under slabs in the garden. In this case we recommend doing your due diligence, and if the house is old, get the drainpipes checked out to avoid any nasty surprises.

Rodents and other pests

Broken drainpipes can attract unwanted visitors in the form of rodents. They can use the pipes to get under and into the building, so if you’ve noticed the presence of more rats or mice around the house, the pipes could be where they’re gaining entry.

TIP: Non-return valves on the ends of your pipes help to stop any wastewater getting back into the pipes, as they only allow for a one-way flow. They also stop rodents from using the pipes to get around.

What causes drains to collapse?

There are a few key reasons as to why a drain may collapse, including invading tree roots, misaligned pipes, ground movement and general wear and tear.

Tree roots

Trees are forever in search of water, and depending on the size of the tree, its roots can spread for metres and metres under the ground. This means that at some point they’re likely to encounter drainage pipes. If your house’s drainage pipes are made of earthenware, they’re easily damaged by invading tree roots.

Misaligned Pipes
Misaligned pipes cause water leakage, which can cause soil erosion and in turn a collapsed drain.

Repetitive freezing and melting

The weather can play in a big part in the overall health of your drainage system. In winter when the ground freezes, it expands, and when it melts, it settles again. Over time, this has a tendency to move the ground that surrounds the drainage pipes, and if it moves enough, the drainpipes can be left with gaps around them. If a big enough gap is created underneath the drainpipe, it’s liable to collapse.

General wear and tear

As with many things, general wear and tear can be the cause of a collapsed drain. As we’ve previously mentioned, drainage for older buildings is typically made of earthenware which perishes over time. It’s also more vulnerable when it comes to ground movement and tree roots compared to the likes of plastic drainage pipes.

TIP: If you’ve recently bought an older house, it can be a good idea to have a professional check your drainage system for any wear and tear to avoid any potential problems in the future.

Who is responsible for collapsed drains?

Put simply, a homeowner is only responsible for the drains inside their property’s boundary and the drains connected to their property. If the problem is not within your property’s boundary or connects to the public sewerage system, it’s the responsibility of either a neighbour, or your local water company. Private sewers or drains are the responsibility of the owner. This has been the case since October 2011, when the regulations were updated. Pre 2011, homeowners were not only responsible for the drains on their property, but in some cases those outside their property’s boundary or where they connected to the public sewer too.

If you have a more unique situation, you can find more detailed information on collapsed drain responsibilities in this government document.

If you suspect you have a collapsed drain around your property, our advice would be to always get a professional to evaluate the problem. If there is indeed an issue that requires fixing, you’re then able to let the responsible party know or resolve the issue yourself.