What To Do If Your Basement Floods From a Water Main Leak

As winter approaches, the number of broken water mains will double, which (in a worst-case scenario) could result in a cracked main water line that leaves you with a flooded basement. Alternatively, the water main may be broken 25’ away under the sidewalk or street, and still travel all the way back into your home. You may ask β€œhow is it possible that the water would travel this far back into my home?” Unfortunately, it is rather common that the broken water line is nowhere near where the escaped water surfaces. A water leak will find the weakest point in the ground and continue to travel below ground until it finds a weak point in the road, sidewalk or foundation wall. However, regardless of how it happens, the best you can do is prepare. Read on to learn more about what to do when you have sewer water in your basement.

Pinhole leak on main water line inside house

Pinhole leak in water main

What To Do if Your Basement Floods

If you have a flooded basement, you must first locate the house sewer trap. If you are lucky enough the house sewer trap is located in the ground, in this case we suggest removing the sewer caps and letting the leaking water travel through your sewer line and out to the city sewer. In the case of a pinhole leak it is much easier to manage as the amount of water is limited and can simply be diverted into a bucket for a short period of time. The risk in this scenario is that the pipe bursts and this minor leak becomes a huge problem.

Water main leaks under sidewalk and shows up in house


In other cases you may have to make a diversion for the water to travel and reach the sewer trap. This can really be done with any form of a bucket, pipe or even a piece of metal for the water to travel along until it hits the sewer trap. In this picture above there was a great deal of water entering the basement which was leaking from the water main under the sidewalk.

The homeowner had a lead pipe which required the entire service line to be replaced on an emergency basis from the street, to inside the house.

Digging for the new water line installation

Digging for the new water line installation

New copper water line is installed

New copper water line is installed

In another scenario, a utility contractor was working in the roadway in front of the building and hit the property owners water main by accident. The entire basement was flooded with sewage within minutes and in this case the volume of water was too great for the old sewer trap trick.

Basement flood from broken water main


The water had to be turned off from the roadway on an emergency basis before the repair was completed.

Water main turn off in street

Broken pipe in roadway

Knowing what to do when you have a sewage leak in the basement is an excellent skill to have as a homeowner. Visit our blog page to find more resources about home plumbing, water main, and sewer line emergencies.

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