News Article

Built to last: Installing and protecting new water mains

How Denver Water gets the most out of its pipes.

Denver Water crews are hard at work replacing a new water main in west Denver, and they’re making sure the new pipeline is built to last.

The work is taking place on Sheridan Boulevard between West 13th and West 29th avenues, along Denver’s border with Edgewater, Lakewood and Wheat Ridge.

Crews are installing 8,000 feet of new pipes to replace an old stretch of water main that dates to the 1930s. The existing cast-iron pipeline is close to 100 years old and at a point in a pipe’s lifespan where it becomes more likely to break or leak.

Heavy equipment lowers pipe into a trench at night. — Denver Water workers lower a new ductile iron pipe into the ground on Sheridan Boulevard next to Sloan’s Lake in January. Photo credit: Denver Water.

Denver Water also wanted the pipe replaced before construction begins on the new Sheridan Boulevard Multimodal Corridor Plan in a few years.

“As part of our pipe replacement program, we look for pipes that are at risk of failure, and our goal is to replace them before there’s an unexpected problem,” said Katie Ross, engineering manager at Denver Water. “The pipeline under Sheridan has held up well for nearly 100 years, and these improvements ensure reliable water service for the next century.”

The new pipes are made of ductile iron, and Denver Water takes steps to help the pipes withstand the damaging impacts of corrosion so they’ll last longer.

A construction worker stands at the bottom of a trench between two ends of pipe. — A worker guides a new section of pipe into place to build the new water main. Photo credit: Denver Water.

What is corrosion?

Corrosion is a naturally occurring process in which an electrochemical reaction causes metal to decay or deteriorate when it is exposed to moisture, soil and oxygen.

Corrosion happens on pipes, bridges, ships, storage tanks and other things made of metal. Once metal is buried in soil, the corrosion process begins, with the rate of corrosion depending on soil properties, protective pipe coatings and other factors.

“As metal pipes age, corrosion eats away at the pipe wall. What starts as slow thinning can eventually turn into leaks and broken pipes.” said Cian Davis, a senior corrosion engineering specialist at Denver Water. “Once the corrosion reaches a certain point, the pipe will fail.”

A close-up of a hole in a metal pipe. — An example of a hole caused by corrosion on a water main. Photo credit: Denver Water.

Fighting corrosion is a constant battle for Denver Water, which uses underground pipes to deliver water to 1.5 million people. In fact, corrosion is the No. 1 cause of pipe breaks at Denver Water.

Corrosion can’t be stopped, but it can be slowed

To slow the effects of corrosion, Denver Water crews place protective coatings around each piece of new pipe. The most commonly used protective coatings are polyethylene encasement, or “poly wrap” for short.

The wrap provides a barrier between the pipe and the surrounding soil and water, to help slow corrosion and maximize the life of the pipe. Poly wrap also contains a corrosion inhibitor and a biocide for improved protection.

Two construction workers in safety gear pull plastic off a new pipe. — Workers pull “poly wrap” around a new ductile iron pipe. The poly wrap helps protect the pipe from the corrosive impact of the soil. Photo credit: Denver Water.

While the poly wrap serves as a first line of defense for corrosion, it’s not perfect, as moisture can get inside the barrier layer. That’s why Denver Water also uses another measure called cathodic protection to slow down the damaging effects of corrosion.

Workers add cathodic protection techniques on water distribution pipes that are made of steel or ductile iron and installed in corrosive areas.

“Cathodic protection is a technique used to control where corrosion occurs,” said Antonio Flori, corrosion engineering manager at Denver Water.

“Once buried underground, the cathodic protection system diverts corrosion away from the pipe and onto another piece of metal called a sacrificial anode. These sacrificial anodes corrode instead of the pipe and help minimize corrosion-related leaks on the pipe itself.”

Denver Water’s corrosion engineering team has a process for monitoring the cathodic protection systems and replacing exhausted anodes as needed to continue protecting the pipe.

“By using cathodic protection, we can extend the life of a pipe by around 25 years before anodes require replacement. By repeating the process, we can make pipe last over 100 years,” Flori said.

A construction worker inside of a trench uses a welder on a pipe. — A Denver Water worker welds part of a cathodic protection system onto a new pipe. Photo credit: Denver Water.

Denver Water has cathodic protection systems on about 600 miles of pipe used to deliver water to customers and adds more every year.

“Denver Water invests more than $2 million annually on new and retrofitted cathodic protection systems to protect our metallic pipes,” Flori said. “This investment will save Denver Water over $1 billion over the next 50 years, and those savings are passed on directly to our customers.”

A bag of magnesium lays next to an open pipe. — A bag of magnesium is placed near the new pipe. As part of the cathodic protection system, the magnesium acts as an anode and is connected by wires to draw corrosion away from the metal pipe. Photo credit: Denver Water.

Sheridan project timeline

The pipe replacement project on Sheridan Boulevard began in January 2026 and is expected to wrap up in early 2027. Along with the new water main, Denver Water is installing 65 new valves, replacing five fire hydrants and adding five new fire hydrants.

Learn more about the project and sign up for updates on our project page.

A pipe covered in white plastic sits at the bottom of a trench. — Denver Water is replacing 8,000 feet of water main along Sheridan Boulevard. The work will be completed in early 2027. Photo credit: Denver Water.