Here's Why Water Mains Break

It’s a fact of life: water mains break. And when they do, they disrupt the lives of those serviced by them. Breaks can close down roads, cause damage to property and generally wreak havoc on the area around it. So why does it happen? This simple guide can help explain it to your customers.

A city’s water distribution system is made up of an interconnected network of pipes. That system has large transmission lines that feed smaller distribution lines (the ones that go to residents’ homes). A series of valves throughout the city system controls pressure and flow. Water towers store the water until it's needed, then gravity brings it into homes and businesses. Water main breaks can happen anywhere along the way in this system.  

Why do water mains break?

Breaks happen because of a number of different reasons. Here are a few simple animations that explain to your customers why it happens.  

Excavation work

When contractors, utility workers or even homeowners dig in the ground, they can unintentionally hit water pipes with digging equipment. It can happen with a tool as simple as a shovel, or more commonly, with excavation machinery.

digging equipment
Digging in areas around water mains can cause them to rupture if impacted with digging equipment.

Pipe age and material

The older pipes are, the more likely they are to break. Water mains installed before 1980 are often made of cast iron. Cast iron can be brittle and cannot expand and contract easily with temperature changes. When this happens, the pipes have a tendency to crack. There are also older sewer pipes that are made of clay. This material also breaks easily. New water mains are made of ductile iron or plastic pipes.

older pipes
As pipes age the likelihood they will break increase. Likewise, older pipes are often made of material that is more likely to break.

Pressure changes

The pressure inside of a water main can change in a couple different ways. One of the most common ways is through temperature changes. This is sometimes called thermal expansion. As the ground around a pipe freezes and heats, the pipes expand and contract—sometimes causing a rupture. Pressure changes can also occur when fire hydrants are either opened or closed too fast. This is called water hammer.

pressure inside a water main
When the pressure inside a water main changes, it can cause the pipe to burst.

Ground settling

As the soil around a water main settles over time, it can stress the pipes running beneath the ground. If the ground settles enough, the stress can break the pipe.

Ground settling
Ground settling over time can cause water mains to break.

Corrosive soils

Some soils are corrosive and can eat away at pipes over time. This is especially common in iron and other metal pipes. Eventually the corrosion causes the pipe to break. It happens most often at pipe fittings or in pipes that haven't been properly protected from corrosion. The Ductile Iron Pipe Research Association (DIPRA) suggests polyethylene encasement as a popular, economic and successful method of corrosion control. Some communities have opted to use pipe made out of non-corrosive materials such as C-900.

Certain soils can cause pipes to corrode and break.

What can you do when pipes break?

There are a number of things municipalities can do when pipes break and cause problems in a community. It's important to choose a consultant that offers a number of diagnostic and repair solutions, because each case is different. There's the traditional remove and replace method involving digging up and repairing the broken pipe. There's also innovative methods like non-destructive testing and trenchless technology that repairs broken pipes without disturbing the ground around it.

Related Content: These Breakthrough Technologies Reveal Hidden Pipe Defects

Bringing it all together

It’s no doubt, when water mains break, it can disrupt communities. People are left without water and sometimes their travel routes are affected. With a little education, your community’s residents can better understand why this happens and how it’s commonplace in all municipalities.

About the expert

Greg Anderson

Greg Anderson is a civil engineer who understands the importance of educating communities on how their infrastructure works and providing solutions when it doesn’t. Contact Greg

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