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Water Main Break Information

Boulder’s water distribution system is comprised of a network of pipes or “mains” that convey water from the city’s two water treatment facilities to the service lines that serve individual homes and businesses. The water distribution system is pressurized. This pressure prevents contamination from entering the pipes and is what allows water to flow “uphill” to plumbing fixtures on upper floors of homes and businesses.

The city has approximately 460 miles of pipe in the water distribution system. Laid end to end, those pipes would extend from Boulder to Albuquerque. Pipes are usually buried four to five feet below the ground surface. Most water mains in neighborhoods are 8-inches in diameter. Larger pipes are used to carry water from one part of the city to another and to meet fire flow requirements for large buildings. The system also includes pumps, valves and fire hydrants that support day-to-day operations and emergency response.

If you have additional questions, please feel free to call 303-441-3200.

Frequently Asked Questions

How old is the city's water distribution system?

The water distribution system has largely been constructed over time as the city has developed. Roughly 19 percent of the existing pipe was installed between 1900 and 1960. About 68 percent of the system consists of pipes installed between 1960 and 1999. Less than 14 percent of the pipes in the system were installed in 2000 or later. Older pipes are typically iron, while new pipes are typically plastic. Modern iron pipe has special coatings and other protective measures to resist corrosion that were not available or the industry standard when much of the city system was constructed. 

What causes water mains to break?

Water main breaks can be caused by a number of factors, including (but not limited to):

  • Pipe corrosion – Many pipes in the distribution system are made of metals such as ductile iron and cast iron, or have fittings made of metal. Some soil conditions can cause metal pipes or fittings to rust or otherwise corrode, and even a small corroded area can weaken the pipe. The combination of a weakened pipe wall and pressurized water inside the pipe can cause a leak or break.
  • Ground movement – Movement of the surrounding soil may also cause damage to buried pipes. Changes in the water table, freezing and thawing and other natural forces can put stresses on pipes that lead to water main breaks. 
  • Operation of the water distribution system – Breaks can occur when pipes are stressed by operation of the water system. For example, closing a valve too quickly can create a shockwave, called a “water hammer,” through the system that can cause significant damage. This is similar to the force that can cause pipes to rattle when you shut off a faucet quickly in an old house. In a large water main, the forces involved are much greater and can be more destructive.
  • Construction – While the city is required to mark underground utilities prior to public or private construction projects, occasionally a contractor or other utility provider will damage a water main while working nearby.

What happens after a pipe breaks?

When a hole or crack develops in a pipe the pressurized water rushes through the opening. This places additional stress on the pipe and can wash away surrounding soil. If the hole or crack is on the top of the pipe, water may push upward through the ground and spray high into the air. In other cases water escaping a main break may wash away soil from under a roadway until it collapses and then overflow the excavation it has created. In some cases the area around the hole or crack will remain intact, and the leak will reveal itself over time as it bubbles to the surface. 

How does the city know that a main break has occurred?

Main breaks are not predictable and rarely give advance warning. During a major water main break, increased water flows in major pipelines into the city or decreased water levels in storage tanks can be an indicator that there is a problem somewhere in the system. However, those changes do not always indicate a water main break and provide minimal information about the location of the issue. Water main breaks and their specific locations are typically identified based on reports from residents or businesses.

Residents who observe what may be a water main break should call 911 immediately. If a resident observes something unusual related to the water system that does not appear to be an emergency, they can also contact the Public Works Department at 303-413-7100. After hours Public Works emergencies are directed to the city’s Betasso Water Treatment Facility, which is staffed by water treatment operators 24 hours per day, 365 days per year. Water treatment operators are not able to leave the facility to respond to field emergencies due to critical responsibilities at the treatment facility; however, when alerted to a problem, Betasso staff immediately contacts appropriate field staff who can respond.

What happens after the city is notified of a possible water main break?

During normal business hours, a water distribution system operator will suspend other work to respond immediately to the location. After hours, staff at the Betasso Water Treatment facility contacts the assigned standby water distribution system operator. There are approximately 10 certified water distribution system operators who serve as the standby operator on a rotating basis. While all of the operators are qualified to respond, the standby system provides clarity on the first point of contact and assures that there is always a qualified operator ready to respond immediately. Operators who are scheduled for after hours standby take a properly equipped service truck home with them so they can respond directly to an incident. The city does not have a residency requirement and most city employees live outside of the City of Boulder. To be eligible for the standby rotation, an employee must be able to respond in 45 minutes or less.   

What happens once the operator gets to the site?

Unlike the plumbing inside a home where there is usually a single valve that can turn off the water to an entire house, isolating a water main break to stop the flow of water requires both an understanding of the water system’s configuration and its operation.

The city’s water system is laid out in a network similar to the street system. While turning off a “dead end” might only require operation of a single valve, most sections of water main pipe require operation of a specific combination of valves at multiple locations to cut off water to the damaged section, while keeping other customers in service and avoiding contamination of the system. Some valves must remain in an open or closed position to maintain stable operation of the water system. For example, inadvertently opening a valve that separates a higher pressure part of the system from a lower pressure part of the system could introduce a surge that damages a wider area. The sequence and speed at which valves are operated is also a consideration to avoid damage. Opening or closing a valve too quickly can cause a shockwave, known as “water hammer,” that can cause widespread damage. 

Before an operator can physically operate valves to shut off water service to a broken section of pipe, they first must locate them. Valves are physically located on the water main pipes, which are typically buried four to five feet below the surface of the ground. A capped tube called a “valve box” is placed over the top of the valve when it is installed and extends to the ground surface to allow access to the valve for operation. An operator typically must locate all valves in a given intersection to be certain of which one must be turned on or off. Valve box caps are often not easy to find because they may be covered in mud or water from the break, snow, landscaping materials, parked cars, or otherwise obscured. Once the operator finds the appropriate valves and removes any dirt or debris that may be obstructing the operating nut, they must then use a special wrench to operate it.  Knowledge of the number of turns required for different types of valves, appropriate torque, and speed of operation is important in avoiding damage to the valve and the broader water system. Improper operation can also damage the valve and prevent it from sealing. A damaged or inoperable valve would require an operator to reassess and turn off water to a larger geographic area, which can affect more homes and businesses and takes more time. Once the operator has made appropriate valve adjustments, they assess whether the break has been successfully isolated. On level ground, the flow of water out of the pipe will dissipate almost immediately. On steeper terrain, it may take time for the line to drain through the opening. If the combination of valve operations has not successfully cut off the flow of water, the operator will reassess and identify a larger geographic area to take out of service.

Why don't fire fighters or police officers turn off the water?

While fire fighters or police officers are sometimes the first city employees to reach an incident, their primary responsibility is to maintain public safety by keeping traffic and the public away from the water break area. They generally use their vehicles to block streets and redirect traffic until a contractor can respond and implement a work zone traffic control plan. 

The water distribution system operators that serve as standby responders have a minimum of a Colorado Level II Water Distribution Operation Certification. This requires at least two years of operations experience, successful completion of a Level I and Level II certification exam, and a continuing education requirement. The operators work under the oversight of the city’s “Operator in Responsible Charge” designated on the state permit to operate a public water system. City staff has not identified any water systems in Colorado where operation of the public water system has been delegated to fire fighters or police. Staff also understands that Colorado’s approach is consistent with national best practices. Delegating operation of the public water system to uncertified staff with limited skills and experience would increase the risk of operational errors that could substantially impact life, safety and property. In the case of water main breaks, this also increases the risk of increasing the severity of and prolonging the problem. It is not considered feasible for fire fighters or police officers to acquire and maintain proficiency and certification in water distribution system operations while also meeting his or her primary job requirements.

Why doesn't the city keep a water distribution operator on-site 24/7 to respond to emergencies? Wouldn't that avoid a lot of unnecessary damage?

24-hour coverage could be considered through the budget process. The water utility currently provides 24-hour staffing at the two water treatment facilities and for critical facilities in the source water system that could result in catastrophic damage and/or loss of life in the event of a failure.  Providing a single on-site water distribution operator at a central location for hours that are not currently staffed would require a combination of several additional employees and increased overtime costs. It is important to note that due to the nature of water main breaks, the additional staffing would not necessarily have a significant impact on reducing private property damage associated with water main breaks.

Roughly 60 percent of water main breaks are reported during normal business hours.  The water system is generally under greater strain during daytime operations when demands are higher and more frequent operating adjustments are required.  There is also a greater likelihood of an observer identifying and reporting a water main break during the day.  A situation such as a less severe break, in the early morning hours, on a low volume street, might not be observed and reported until daylight.  Once the city is made aware of the break and location, an employee must still travel to the location.   

Finally, once the employee has arrived on site, additional time is required to assess and safely operate the system. As described above, this is rarely a matter of operating a single valve, and valves must be operated slowly to avoid damage to the larger water system. Reducing travel time to the site of an after hours water main break could potentially reduce impacts in some small portion of the total number of breaks. However, because damage can occur within minutes or seconds of a break and is sometimes what triggers the city being notified of the problem, it is unlikely that a reduction in response time would eliminate damage from breaks.

How is a main break repaired?

While the first water distribution system operator to arrive at a site begins work to isolate the break and secure the area, staff and equipment are assembled in preparation to excavate the ground surrounding the section of broken pipe and make a repair. Before a crew can begin excavation, they must wait for representatives from other utility companies (electric, gas, telecommunications, cable, etc.) to arrive at the site and identify any infrastructure they may have in the area. This helps prevent other services from being damaged during repair of the water main. Once they receive clearances from the other utility companies, city crews excavate material from around the water main in the area of the apparent break. If the damage is limited to a small area and the remainder of the pipe is in good condition, a special clamp is used to wrap the pipe and cover the break. If damage is more significant, a larger section of pipe is removed and replaced with new pipe. If the condition of the pipe requires the replacement of a significant length of pipe, crews will develop an interim plan to restore water service to affected homes until repairs can be made. Once the line has been repaired, the crew flushes it to remove any contamination before it is returned to service. In rare cases, the line must be taken out of service for an extended period and disinfected with chlorinate before it can be returned to service. When significant repairs are required, utilities crews generally make a temporary repair to the street so that can be opened to traffic. City Transportation Maintenance Crews or a private contractor is responsible for repaving the street at a future date. 

How often do water main breaks occur?

The city responded to 69 water main breaks in 2015. The number of breaks varies from year to year, but the average between 2010 and 2015 is about 70 per year. While every water system has significantly different characteristics (size, age, pipe materials, etc.), the city does compare water main break data from other cities for benchmarking purposes. The city average of 70 breaks per year across 460 miles of pipe is approximately 15 breaks per 100 miles of pipe. Compared to national data, 15 breaks per 100 miles is below the average (24 breaks/100 miles) and close to the median (13 breaks per 100 miles). 

Measures such as funding a more aggressive water main replacement program and developing an active leak detection program do appear to have made some impact on reducing total breaks. Between 2002 and 2009 there were four years with more than 80 breaks including a high of 106 in 2002. The highest number of breaks in the last five years was 74 in 2013.

Does the city do preventative maintenance to prevent water main breaks?

The city performs a variety of preventative maintenance on the water distribution system including exercising valves to help ensure operation during emergencies, flushing to maintain water quality, leak detection to reduce water loss, and operation and inspection of fire hydrants to help ensure proper operation during a fire. Because the actual pipes are buried and operate under pressure, best practice maintenance of water distribution systems does not include routine inspection of the interior or exterior of the pipes. Inspection of the interior of a pressurized pipe would involve excavation and shutting off water to customers in order to drain the pipe. This activity could present a contamination risk, could stress the pipe, and would require customer outages. Best practice maintenance of the water mains is different than best practice for gravity flow sewer pipes, where TV cameras are routinely inserted via a manhole to do interior inspection. Inspection of the exterior of a buried water distribution pipe would require excavation. Because the majority of the cost of replacing a water distribution main is associated with the excavation (the actual pipe is about 20 percent of the cost), it is more cost effective to replace a questionable pipe than to dig it up, inspect it and rebury it.    

Why doesn't the city just replace all of the old water mains now so they don't break?

The city currently spends about $3.1 million per year to replace aging water mains. This funding supported replacement of about 4 miles of pipe in 2015. Replacing the entire water system with new pipes would cost many millions of dollars, would have significant public impacts, and would likely result in replacement of many pipes that still have useful life remaining. Water break history is one factor in prioritizing funding, but other criteria such as pipe age, pipe material, location, soil corrosiveness, and, consequences of failure also factor in. It is likely that as the city’s water system continues to age that increased investment will be needed to avoid an increase in water main breaks. 

Does the city have "early warning technology" to detect breaks? Could we get this technology?

The city has technology that can help identify a water main break or leak after it happens. For example after the Feb. 15 water main break in Norwood Avenue, the city’s water treatment facility received alarms indicating increased flow in the main pipelines into the city and reduced levels in treated water storage tanks. Once the damaged pipe was isolated from the rest of the system, the system stabilized. Because the tanks and pipelines serve a very large geographic area (much of the city) an alarm would not allow location of a specific break. Alarms could also be triggered by a fire or other high-water-demand issue. 

Some very large water systems, such as Denver Water, have sensors with automated valves on the largest water transmission main—pipes much larger than those found in city neighborhoods that would have catastrophic impacts if they failed. Even that type of technology is reacting to a failure that has already occurred and not heading off one that is about to happen.  

My taxes have increased and my water bill tripled after the 2013 flood. Why haven't these issues with the water system been addressed?

The city operates three separate utilities enterprises that are all included on the same monthly bill. Enterprises are funded by associated rates and fees, and not by taxes. In 2014, City Council approved 2015 rate increases of 30 percent in the Wastewater fund and 75 percent in Stormwater and Flood Management Utility. The increase in wastewater rates was largely driven by a desire to expedite replacement of aging pipes in the wastewater collection system, from about a 100-year time horizon to about a 20-year time horizon. The increase in stormwater and flood management utility rates was largely driven by a desire to pursue additional flood mitigation projects on major creeks. The 6-year capital improvements program approved by City Council last year included projected rate increases in the water fund to expedite replacement and rehabilitation of aging infrastructure. 

Is there anything the city can do about high water pressure in homes?

Most homes have a pressure reducing valve or “PRV” on the water service line just after it enters the house. If pressures are unusually high, the PRV may be broken or one may not have been installed by the builder. A licensed plumber can assess an existing PRV to make sure it is working properly or install one if there is not already one present. 

The city has eight hydroelectric facilities and several pressure reducing valves that help manage overall pressure in the system. The water system must have sufficient pressure to meet variety of requirements, such as fire flows, service to upper floors of buildings, service to parts of the city that are at a higher elevations, service to houses that lose pressure due to long service lines from the street, among others. As a result, higher pressures in some areas are necessary to maintain acceptable pressure in others.