• Pay Bill
  • Customer Support
  • Contact
  • Emergencies
  • Español

Relining Pipes

As part of Denver Water’s ongoing efforts to provide a reliable, high-quality water supply, Denver Water and its contractor Mainlining Service are doing routine pipeline maintenance work from late April through the end of November 2014.

Each year, Denver Water identifies pipeline sections to recondition during the warmer months. Plans for 2014 include four Denver neighborhoods and cover a total of 39,000 feet of pipeline.

Frequently asked questions

  • What is the purpose of this project?

    Cast-iron pipe after it has been rehabilitated with cement mortar lining; cast-iron pipe before it has been rehabilitated.Like many other utilities, Denver Water at one time installed pipelines made of cast iron. Over time, cast iron can corrode and may cause water discoloration, taste issues and decreased pressure. Corroded pipes may also be more susceptible to maintenance concerns such as leaks or main breaks.

    Despite these issues, cast iron is very sturdy. With proper maintenance and improvements, cast iron pipes can provide reliable service for decades to come.

    This routine project involves cleaning the insides of pipelines and applying a new lining. This is a cost-effective, minimally invasive alternative to pipe replacement, which can bring significant construction impacts to streets, landscapes and water service.

  • How are the pipes relined?

    One section at a time, crews pass a steel scraper through pipes and flush them with water. Crews then guide machines that apply cement mortar and smooth it against pipes’ interiors.

    The new lining protects pipes against future interior corrosion and creates a barrier against leakage, adding many more years to pipes’ ability to provide high-quality water supplies and adequate flows for fire protection.

  • How long does the project take?

    It’s hard for crews to know exactly when they will be working within specific streets during this project. Once work starts on a block, it can last four months.

  • Does the project impact customers' water service?

    Because water cannot be running in pipes during cleaning and relining, crews temporarily reroute — or bypass — water to customers by setting up above-ground water supply systems.

    Although Denver Water and contractors do their best to prevent issues, being on bypass can cause short-term inconveniences such as:

    • Water pressure increases or decreases.
    • Water temperature increases.
    • Brief water service interruptions when the bypass systems are turned on and turned off.

    Even if they are not placed on bypass, customers who live near the work area may also notice temporary service changes such as increased or decreased water pressure.

  • What are the impacts to traffic?

    Motorists, pedestrians and residents can expect to see:

    • Hoses connected to fire hydrants and PVC piping along streets.
    • Traffic lane and street parking closures.
    • Water running in streets for required water quality-related flushing.
    • Construction equipment and material such as rocks.
    • Metal covers on temporary street openings such as manholes.
    • Asphalt paving activities.

    These temporary changes mean it’s important for people to use caution when driving and walking near work areas and to pay attention to signage.

  • How do customers know whether they will be impacted?

    Customers going on bypass receive notices on their doors, and others may also receive notices explaining that a planned work area is nearby. Denver Water has also been sharing information with neighborhood resources such as elected officials’ offices and associations representing businesses and homeowners.

    Denver Water and Mainlining Service truly appreciate the community’s patience during this project. Although relining pipes can cause disruptions, it is an integral part of Denver Water’s efforts to provide the highest quality water possible to its customers.

  • Why is water allowed to run in the streets during this process?

    To ensure Denver Water’s supply meets or exceeds water quality standards, crews must flush water through the newly-lined pipes as a part of the disinfection process. Sometimes they may need a second flushing to provide additional cleaning.

    Crews will also flush the temporary above-ground systems to ensure the hoses and PVC piping are providing water that is both clean and cool.

    Denver Water strives to be a leader in water conservation and understands that water in streets can be disconcerting as well as inconvenient. However, these flushing activities are necessary because they ensure water boasts the high quality and aesthetics Denver Water customers have come to expect.


  • For water service issues or billing questions during regular hours (weekdays, 7:30 a.m. to 5:30 p.m.): Customer Care, 303-893-2444
  • For water service emergencies off-hours (evenings, weekends and holidays): 303-628-6801
  • For more information: Dana Strongin, public affairs, 303-607-3132; or Mark Almond, project manager, 303-628-6579