Blocked Sewer & Cross Bore Safety

Blocked sewer? Make the call for safety first.

Logo of Ontario One CallUnderground natural gas pipes that were mistakenly installed through sewer or septic pipes are known as cross bores. Left undisturbed, crossbores aren’t an immediate safety risk. However, they can be dangerous as the equipment used to unclog sewer and septic pipes can easily penetrate a natural gas pipe and lead to the dangerous release of natural gas.

To prevent the risk of a gas leak, explosion or fire, call Ontario One Call at 1-800-400-2255.

Before you attempt to clear a blocked sewer or septic pipe outside the walls of your home, or have it cleared by a contractor or a plumber, contact Ontario One Call for a free on-site sewer safety inspection. Then work on your sewer can be completed safely.

Don't mess with a cross bore.

It's important to know what's below before your plumber goes to work with motorized equipment. WATCH AND STAY SAFE

Follow a few simple steps to keep your meter and your meter reader safe. WATCH AND STAY SAFE

Partners in safety

We all play a role in preventing and minimizing the risk of unintended cross bore intersections. We've provided important safety information and tips for residents, contractors and municipalities. Click below to view each page.


What is a utility cross bore?

A utility cross bore is an unintended intersection of an existing underground utility such as a natural gas pipeline or sewer line by a second utility. This happens when utilities are installed using trenchless drilling, also known as boring. The Cross Bore Safety Program deals specifically with the unintended intersection of a sewer line by a natural gas line.

Is this a significant problem?

Instances of natural gas lines intersecting sewer lines are rare but they have been found in our service area. Left undisturbed they do not pose an immediate safety risk, although they may cause a sewer blockage. However if the gas line is damaged through sewer cleaning activity, the natural gas may enter the sewer line and pose an immediate safety risk. Although there have been no serious incidents in Canada there have been over 20 in the United States.

Why do they happen?

Like many natural gas distribution utilities, we often uses trenchless technologies to install underground pipelines. Trenchless installation is very effective in established areas as it all but eliminates the disturbance to roads, environmentally sensitive areas, driveways, gardens and lawns, as well as the roots of large trees, that occurs when digging an open trench.

But because the trenchless drilling machine operator can't actually see the head of the boring equipment during tunnelling, they rely heavily on accurate "locates" to show them the location of other existing underground utilities. Unlike other types of underground utilities, sewers are traditionally difficult to locate. They are made of non-metallic materials and are installed without any other type of aid to allow them to be located from above ground. Sewers can also be very old, records can be incomplete and "ownership" of the sewer infrastructure usually changes from the municipality to the property owner at some point between the sewer main and the building. In addition, if for some reason either the gas line or the sewer line was installed at an unusual depth and the sewer line could not be accurately located, a conflict can occur.

How do I make sure my sewer is safe?

The most important thing you can do is call Ontario One Call at 1-800-400-2255 and request a free sewer safety inspection before using mechanical or high-pressure water jetting equipment to try to clear a blockage beyond the walls of the building. A blocked sewer can be a stressful situation and you'll want it resolved fast. That's why these inspections are treated as emergency calls with a goal of resolving the issue as quickly as possible. Your safety is the number one goal.

Switching to natural gas? Enbridge Gas or one of our construction partners will visit you to determine where existing utilities are already installed on your property. Please make sure they are provided with prompt and accurate information.

You may also be contacted by Enbridge Gas or one of our construction partners when a new construction or a gas line replacement project is being planned for your neighbourhood. Again, please provide them with the most accurate information possible so a cross bore on your property can be avoided.