Home Improvement

How to Fix a Broken Drain Pipe Underground

If your house is a living organism, the pipe system could be considered as its veins and arteries. And just like with our own bodies, you should always take the “health” of your pipes very seriously. Because once there’s a problem in this complex system, it may take several days to be fixed even if you know what you’re doing.

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If a pipe breaks, the faster you act, the better. However, a broken drain pipe can be even trickier. In this post, the Fantastic Services team will explain how to fix a broken drain pipe underground and all the complications that might come from the damage. So continue reading if you are someone who wishes to fix their plumbing problems on their own.

Causes of a broken underground pipe

Underground drain pipes are less likely to get damaged since their location offers them good protection from the elements and any external physical damage. However, it’s still possible for underground drain pipes to rupture. The most common reasons are:

  • Freezing temperatures. The number one cause of a broken pipe is when water freezes inside it. This is the reason why many homeowners winterproof their piping system.
  • General wear and tear. Water can destroy any surface but it can take decades before a pipe sustains any serious damage. Homeowners usually organise pipe inspections every ten years or so to prevent small problems from escalating.
  • Blockage. It’s possible that the blockage from drains and toilets to move through the rest of the piping system and make it much more difficult to clear. The intense pressure could eventually cause a rupture.
  • Tree roots. If you or your neighbours have trees nearby, their roots could wrap around an underground pipe until it bursts. These are rare cases but it happens.

Signs of a broken underground pipe

  • Flooding. If you notice a puddle of water forming in your basement, you probably have water damage.
  • Bad odour. The smell of sewage is a sign of not only damaged pipes but also a good indicator as to where the damage is. If you smell raw sewage in your yard, the problem is definitely the underground drain pipe.
  • Mould. If the damp spots are left unattended for a long time, they would eventually grow mould. Mould is not only unsightly but it could pose a health risk to people with allergies and asthma.
  • Lush greenery. Because of the excess water that gets dumped in your yard, there’s bound to be some grassy patches that thrive more than the rest.
  • Poor water quality. If the water coming out of the faucet is foggy or coloured in a shade of brown, then your water supply is contaminated due to the damage.
  • High water bill. If you have a leak in a drain pipe under the concrete slab of your basement, it would take a lot of time until it’s discovered, as you won’t see any water damage. In these cases, the only sign would be the suddenly high water bill.
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How to locate the broken underground pipe

  • Turn off all water faucets. If you’re not sure whether you have a leak or not, you can turn off all water faucets and check your water metre. If it’s calculating water usage, you definitely have a leak.
  • Turn off every noise-producing appliance. If you still can’t find the leak, turn off all sounds including the TV, the radio and everything else. If there is running or dripping water, you should be able to hear it.
  • Follow the smell. Sometimes neither noise nor sight is needed to find the source of your damage. When the smell of sewage reaches you, just follow your nose.
  • Examine the water damage signs. If a pipe has broken somewhere inside your house, you will notice peeling paint, bubbling walls, mould, and even obvious flooding in your bathroom, kitchen or inside your wall. If you don’t have any of these, but your water metre is still telling you there’s a leak, then the problem is probably underground.
  • Check the basement and the yard. Now that you’re certain the problem is underground, you have to check your basement and yard for signs of water damage. If you see flooding, swampy patches, lush greenery, mould and if the sharp smell of sewage mercilessly assaults your nose, then you have a broken drain pipe.

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How to fix a broken drain pipe underground

Time needed: 3 hours.

Once you’ve found the location of the leakage, you’ll have to fix it. Depending on the place, you might have to dig the soil in your yard or break the concrete slab in your basement in order to reach the damaged part of the pipe. In both cases, it will take a lot of physical effort and specialized tools to do the job properly.

  1. Turn off the main water supply to your house.

    It should be somewhere in your yard. If you live in an apartment complex, you might need to call someone from the city waterworks to do this. With the water not spilling out anymore, you can start the procedure.

  2. Reach the damaged pipe.

    Your next task is to uncover the broken part of the drain pipe. If it’s in the yard, arm yourself with a shovel. If it’s under the concrete slab of your basement, you’ll need heavy-duty equipment. Your main goal here is to clear the whole pipeline, not just the damaged part. Also, you’ll need to dig about 15 centimetres under the pipe.

  3. Check the entire line for wear.

    The leak might not be the only problem, so while you’re here, make sure to examine for general wear and tear. You might end up having to replace the entire line from the street to the house.

  4. Cut off the damaged spot.

    You can make the cut with a hacksaw, a metal cutting blade, or a tubing cutter. You’ll need to cut about 30 centimetres from the tear from both sides and replace this piece with a brand new copper pipe.

  5. Sand the edges and the inside of the existing pipe.

    Use a wire brush to smoothen the inside of the pipe, as well as the cut edges.

  6. Connect the new couplings.

    Fit the new pipe into place and slide the slip coupling so that one half of each coupling is on the old pipe and the other is on the new. Heat the coupling from underneath with a propane torch and at the same time put a piece of lead-free solder wire on the edge of the coupling that connects to the old pipe. When you see the solder drip, put another piece of solder atop the other edge of the coupling. Do this on both couplings.

For additional protection from the elements, you can wrap a tar base insulator around the new section of your drain pipe.

Hire professional technicians to fix a broken drain pipe

Now that we’ve explained how to fix a broken pipe underground, some of you might think that this is a job that could be easily completed by yourself with no problems. Still, others might decide to call a professional plumber to fix the damage and we strongly recommend this option instead of the first one. We at Fantastic Services advise our readers not to attempt repair projects if you’re not confident in your skills and knowledge. If there is a broken drainpipe, and you prefer to leave it to the professionals, get in touch as soon as possible. Check our plumbers cost guide, to get an idea of much you would be charged on average.

Visit the main website for price rates on our professional plumbers!


  • The most common causes for a broken underground drain pipe is general wear and tear,  freezing temperature and blockage;
  • The signs for a broken underground pipe are flooding, bad odour, mould, poor water quality and high water bill;
  • You can locate the damaged underground pipe by following the signs of water damage;
  • Fixing a broken drain pipe underground needs a lot of physical effort and the proper tools and skills to do, which is why the Fantastic Services team recommends that you seek the help of a professional plumber.

The best way to keep this problem out of your life is to make sure it never happens in the first place. Take measures to insulate your pipes, have regular inspections and keep your drains and toilets free of blockage. Prevention is the best medicine. If you’re not certain when was the last time you inspected your piping system, contact a professional. If your house is already experiencing signs of damage, get in touch with a certified plumber immediately.


Have you ever had to deal with a broken drain pipe underground? Did you fix it yourself or did you call professionals? Tell us in the comments!

Image source: Quality Stock Arts/shutterctock.com

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