In the midst of the coronavirus pandemic, learning about cross bores is important, as certain lifestyle changes you may have made over the past few months could turn an existing cross bore condition into a potentially dangerous situation. Fortunately, unlike many items on your list of concerns these days, dealing with a cross bore is something that you can do something about besides just worry.

So, what is a “cross bore” and why is it important for you to know about it? Simply put, a cross bore is the unintended intersection of two utility lines. This article is concerned specifically with natural gas utility and unpressurized sanitary sewer lines, both of which you likely have on your property. An “unintended intersection,” means the penetration of a sanitary sewer line by a gas utility line.


According to the Cross Bore Safety Association, this is not an uncommon condition and, although statistics vary, some estimates suggest that it occurs at an average rate of 0.4 cross bores per mile of sewer line. So how does it happen?

Cross bores most frequently occur in association with “trenchless” methods of utility line installation. In other words, it involves installing a utility line without digging up the ground. The reasons for doing this typically involve minimizing surface disruption, increasing the speed of installation and reducing costs. The downside to this method is that historically, installers have not been able see when the installed utility line penetrates a sanitary sewer line. The immediate result is typically uneventful, until the affected sewer line becomes blocked.

As far back as 1976, there have been documented incidents of attempts to clear blocked sewer lines where there is an undiscovered cross bore. The resulting rupture of the intersecting gas utility line by some mechanical device, like a root-cutter, allows gas to enter a home through the sewer where it is accidentally ignited, causing an explosion.


As the existence of cross bores has become better understood, steps are being taken to eliminate existing cross bores and prevent them from occurring.

If you’ve been wondering what all of this has to do with the coronavirus pandemic, keep in mind that more people at home for more hours means more sanitary sewer use. The inevitable result? More blocked sewer lines.

According to experts, here’s the part where you can make a difference. First, be mindful to put only toilet paper into the sewer. Second, in the event you have trouble with your sewer line, make sure your plumber uses a camera to visualize any blockage before attempting to remove it.


To see what a cross-bore looks like, and to learn more about excavation safety, visit

This article is courtesy of StatePoint Media.