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Denver Water, state and federal agencies consider next steps on lead

Building on decades of work to curb lead in drinking water, the utility is looking at the next phase.

Denver Water’s most important responsibility is delivering safe drinking water to its customers.

The utility and its employees take pride in their work to deliver water for more than 100 years to its customers, which today number about 1.4 million people in Denver and surrounding suburbs.

As Colorado’s largest provider of drinking water, Denver Water also is proud of its track record on safety and its leadership in adapting through the decades as science and the industry have evolved. That’s particularly true when it comes to lead getting into drinking water, an issue in the city and surrounding suburbs due to the existence of customer-owned lead service lines and lead elements in customers’ plumbing.

The Evolution of Lead in Drinking Water graphic.

“There is no lead in the drinking water Denver Water delivers from its treatment plants, but lead can enter into water as it leaves our system and passes through customer-owned pipes and plumbing on their property and in their homes,” said Jim Lochhead, Denver Water’s CEO/Manager.

In the first half of the 20th century, lead was a cheap, easy to work with and readily available material to use when forming small pipelines that carry drinking water from utility pipelines in the street into customers’ homes. But these lead service lines pose a threat in the community, particularly to children, infants and pregnant women.

Over the past several years, Denver Water has taken steps to protect public health by removing lead service lines when its crews find them while performing other work. Denver Water has offered free water quality tests to customers worried about the existence of lead in their home’s service line or plumbing. More than 5,400 requests have been made since May 2016. And the utility has spent years sharing information with its customers about the lead issue.

Denver Water, state and federal regulators have also been working on the next evolution of decades worth of efforts to protect the public from the effects of lead used long ago.

The Colorado Department of Public Health and Environment in March 2018 required Denver Water to begin preparations to use a food additive called orthophosphate to protect public health from the effects of lead leaching into drinking water from these old, customer-owned lead service lines.

After months of discussion with regulators and stakeholders, as well as years of research, Denver Water is preparing to formally propose an alternative. The proposal is a multipart program that would include rapidly accelerating existing efforts to remove all old lead lines in its service area.

A decision by the Environmental Protection Agency is expected by the end of 2019.

Crises in other cities, such as Flint, Michigan, have thrown the issues surrounding lead into focus. The issue in Denver, however, is nowhere near the level of urgency that these other cities have experienced, as Denver Water currently uses a pH adjustment to reduce the risk of lead and other metals from getting into drinking water from service lines and household plumbing. Only once, in 2012, have the action levels set by the EPA exceeded the standard set for water utilities — which ultimately indicates that an adjustment to their water is necessary to lessen corrosion.

And that is what is occurring now.

Denver Water is considering the next steps to take as the utility builds on its collective, decadeslong efforts to protect public health and reduce the likelihood of lead getting into drinking water.

Both orthophosphate and pH, when added to drinking water, coats the inside of pipes and over time reduces the likelihood of lead getting into the water as it passes through the customer’s service line, indoor pipes and plumbing to the faucet.

Drawbacks to Denver Water using orthophosphate include the ripple effects of adding this nutrient into the larger water supply that can, under the right conditions, set off a chain of problematic events such as accelerating the growth of algae not only downstream of the city, but in Colorado’s high-altitude lakes, reservoirs and ponds.

“We are committed to taking the right steps to reduce the likelihood of lead entering into water from customers’ lead service lines and other sources of lead in their homes. At the same time, Denver Water recognizes the need to protect the watersheds we rely on to provide water and the high-altitude, arid environment we all live in,” Lochhead said.

Cost also is an issue. While Denver Water would invest millions in adding orthophosphate to its drinking water, other entities, including neighboring water providers and the region’s Metro Wastewater Reclamation District, would have to spend millions trying to remove the nutrient from the water. It’s also expected that the nutrient would runoff into the rivers and streams, such as the South Platte River, from customers’ lawns and landscapes impacting downstream users.

Denver Water is preparing to formally propose its program which has three main parts:

  • It calls for Denver Water to rapidly accelerate its existing efforts to remove lead service lines, wherever they’re found in Denver Water’s service area, and replace them with copper service lines. The goal is to replace an estimated 50,000 to 90,000 lead service lines in 15 years.
  • This plan includes distributing water filters, certified to remove lead from water, to customers who may have a lead service line to use until the line is replaced.
  • It also involves raising the pH of the water from 7.8 to 8.8 to protect customers who have a lead service line, as well as those who have lead solder joining pipes in their plumbing or lead pieces in their faucets.

These days, about 1,200 lead service lines are replaced every year in Denver Water’s service area.


Denver Water expects to formally propose the multipart program to the EPA and CDPHE in August. The EPA is expected to make its decision by the end of the year. If EPA makes the determination that the alternative is as efficient as orthophosphate at reducing lead at customer’s faucets and then approves it, Denver Water must then request that CDPHE modify the designated optimal treatment. Whether or not CDPHE decides to change the designation, optimal corrosion control implementation will begin in March 2020.

“It’s important to remember there is no health crisis around lead that Denver Water, state and federal regulators are responding to,” said Nicole Poncelet-Johnson, director of water quality and treatment at Denver Water. “We continue to monitor our system and the quality of our water every day. Every year we collect and analyze tens of thousands of samples. Denver Water is in compliance with state and federal regulations regarding lead as well as other standards.”

If federal officials decide in favor of Denver Water’s proposal to accelerate the removal of lead service lines from its service area over 15 years, it will be the third such program — and the largest — approved in the United States.

Widespread use of lead

Lead, a naturally occurring, silvery blue, soft and malleable metal, has been a part of human society for thousands of years.

The Romans used lead pipes to carry water to their cities. Powdered lead has been an ingredient in makeup since the time of the Egyptian queen Cleopatra.

Today, scientists and society are more aware than in the past of the dangers posed by the use of lead in paint, gasoline and drinking water infrastructure.

The material that once was commonplace in many manufactured goods has become the target of regulations aimed at reducing or eliminating its use.

The Consumer Product Safety Commission in September 1977 banned lead from the consumer paint market, a change that took effect in 1978. Amendments to the Clean Air Act in 1991 required lead be removed from gasoline by 1995.

In the water industry, concerns about lead pipes have evolved over decades. This is particularly true for the small lead service lines that in Denver are customer-owned and that builders and developers installed to bring water from the main delivery pipe in the street into the home. Industry has evolved. So has Denver Water’s approach to these lead pipes.

But because these lead service lines, indoor plumbing and faucets are owned by the customer — not Denver Water — tackling the lead service line issue presents some unique challenges. The biggest challenge is that Denver Water doesn’t know exactly which homes and buildings have lead service lines. Nor do most of its customers.

Denver Water estimates there are between 50,000 and 90,000 lead service lines buried throughout its service area in the city and surrounding suburbs. Denver Water currently has about 312,000 service lines in its system.

In Denver, homes built before 1951 are most likely to have lead service lines, based on Denver Water’s experience over the years with lead lines in its service area. Until 1987, household copper pipes were connected with solder made with lead. And faucets and other plumbing pieces made before 2014 are likely to have some lead in them.

Denver Water knows those dates because in 1949, the utility changed its standards to allow builders to use galvanized steel and copper pipes instead of lead. Based on the lead service lines Denver Water crews have encountered, it appears most of the lead pipe inventory in Denver was gone by the early 1950s.

In 1971, Denver Water banned the use of lead for service lines.

Lead service lines, like the ones pictured here, were initially installed by builders most likely before or during the mid-1950s and are owned by customers.


Congress followed suit 15 years later, in 1986, when it approved amendments to the Safe Drinking Water Act that banned the use of lead in drinking water pipes and the solder used to hold pieces of copper pipe together. So, lead solder was phased out of use at that time.

And in 2011, Congress passed the Reduction of Lead in Drinking Water Act, which lowered the amount of lead allowed to be in “lead-free” household faucets and faucet parts from 8% to 0.25%. The new rules took effect in January 2014.

Protecting the public and looking for lead

Water, by its nature, is corrosive. Anyone who leaves a nice gardening tool out in the rain knows rust will develop on it.

Knowing the corrosive power of water, regulators and the industry over decades developed a series of tests and standards to monitor water systems for the presence of lead. They’ve also developed protocols around what water utilities, such as Denver Water, can and should do to reduce water from corroding lead pipes.

Since 1992, Denver Water has tested the water that comes out of customers’ faucets in their homes as required by the EPA’s Lead and Copper Rule, which was been established in 1991.

The tests look for the presence of lead in the water sample and its concentration level, or how much lead is in the water sample. Under the EPA’s rule, the need for additional action is required if more than 10% of the homes tested during a testing period come back with lead levels above 15 parts per billion.

In addition to the regular testing, Denver Water in the early 1990s also researched what steps it could take to protect its customers and community.

In 1994, Denver Water determined that it could reduce the corrosive power of its drinking water by adjusting the pH of the water, thereby reducing the likelihood of lead seeping into water.

The pH level of drinking water reflects how acidic it is. PH is measured on a scale of 0 to 14, with 7 considered neutral, meaning there’s a balance between the water’s acidity and alkalinity.

Denver Water determined that raising the water’s pH to 7.8, making it less acidic and allowing it to create a protective coating on the interior of lead service pipes, reduces the chances of lead leaching into water. State health officials approved the measure at that time.

Exceeding the EPA’s threshold in 2012

By 2012, Denver Water had been monitoring its system for lead for three decades and adjusting the pH of the drinking water to protect customers from lead for nearly that long.

But in 2012, Denver Water’s routine monitoring for lead, via water samples collected from customers’ homes with known lead service lines or lead solder, led to results that exceeded the federal threshold at which action is required. In other words, more than 10% of the samples done that year from homes with lead service lines or lead solder tested positive for lead at concentrations above 15 parts per billion.

To date, the 2012 results are the only time since 1992 that more than 10% of the test results during a testing period have been above the 15 parts per billion threshold.

But the rule required action based on the 2012 results. So did state and federal officials. And so did Denver Water’s leadership.

“At the end of the day, we’re a public health provider and we weren’t going to sit around and wait for new regulations and studies,” said Lochhead. “Our communities will be safer with no lead service lines in the ground, so we developed a program to start removing this issue at the source, among other efforts to help our customers.”

Denver Water responded to the need for action on many fronts, including:

  • Launching the largest public health education campaign the utility had ever undertaken, attending community meetings, meeting with elected public officials and sending customers information about lead not once but repeatedly since that time.
  • Studying lead service lines excavated from customer homes to learn what more could be done to prevent lead from leaching into drinking water.

In 2016, Denver Water launched its Lead Reduction Program, which included:

  • Replacing customer-owned lead service lines whenever they were encountered during routine water main or major road construction work.
  • Offering of free water quality tests for any customer worried about lead in their home’s drinking water. To date, more than 5,400 requests have been made.
  • Partnering with Denver Public Schools, Littleton Public Schools and Douglas County School District to test for lead in the schools.
  • Implementing policies to ensure builders and developers would replace lead service lines when home sites were redeveloped.

These days, about 1,200 lead service lines are replaced every year in Denver Water’s service area. The lead is being ripped out of the community.

But at that pace, it will take 40 to 60 years to replace all the estimated lead service lines believed to be buried in Denver Water’s service area in the city and suburbs.

What will be the next step?

More must be done to protect public health. Denver Water, state and federal health officials agree on that.

But the question is what the best path forward is for the community and public health.

In March 2018, CDPHE required Denver Water to take the steps necessary to add orthophosphate to its drinking water by March 2020. The decision was based on research Denver Water conducted with the lead service lines it had tested.

Denver Water’s research indicated adding orthophosphate to the water, which would coat the interior of lead service lines, over time would reduce lead levels in drinking water in customers’ homes by 74%. That’s slightly more than the 60% to 65% reduction in lead levels reached by raising pH levels from 7.8 to 8.8, according to the same research.

Sections of lead service line pipe undergo different treatments as part of a corrosion control study at Marston Treatment Plant.


But a 74% reduction is a lot less than the near-total reduction in lead contamination that could be reached if the lead service lines were removed altogether.

Other water utilities elsewhere in the United States use orthophosphate to protect their customers.

But the ramifications of adding orthophosphate into Colorado’s high-altitude, semi-arid environment extend far beyond Denver Water, the state’s largest drinking water provider, Lochhead said.

Denver Water’s experts believe it will take about 60 years of using orthophosphate to reduce lead levels by 74% across all the lead service lines believed to be in its service area. Those years will be costly to water users throughout metro Denver and potentially irreversibly damage the wider environment.

On a regional level, what Denver Water puts into the drinking water supply Metro Wastewater Reclamation District, which handles the waste stream for many customers, including 70% of Denver Water’s customers, must invest in removing. Neighboring water utilities whose network of water pipes connect with Denver Water’s network, ranging from Highlands Ranch and Parker on the south side of the metro area to Adams County and Thornton on the north side, also must invest in removing the additive.

But because many customers use Denver Water to water their lawns, gardens and landscapes, the orthophosphate in the water is expected to runoff into the South Platte River, affecting the fish, wildlife and environment in and along the river, as well as communities downstream that rely on the river for their own drinking water.

“There’s a ripple effect. And we’re interested in seeing if there is a better alternative that will protect the public health and environment,” Lochhead said.

Worried about the widespread impacts, in 2018 a stakeholder group involving Metro Wastewater, environmental groups, local officials and officials from CDPHE formed to explore the potential impacts of adding orthophosphate as well as alternative paths.

The result of those meetings is the three-part proposal Denver Water will make to the EPA and CDPHE in August.

“Denver Water values the ongoing input from our customers and there is planned community outreach being conducted over the next several months for impacted residents can learn more and weigh in,” Lochhead said.