We Need a Safe Breathing #Water Act – #Legionella #aerosols #IAQ

Forty years ago this month, more than 200 cases of Legionnaires disease, resulting in 29 deaths, occurred at hotel hosting an American Legion conference in Philadelphia — giving the disease its name and the American public its first media-amplified look at an outbreak. 

Four decades later we’re still being exposed to Legionella bacteria — the rate of reported occurrences has quadrupled since 2000 according to a recent CDC report — but we’ve done little to stifle its primary vector: water in the air.

After months of investigation through the summer and into the fall of 1976, officials traced the Philadelphia outbreak to contaminated water in the hotel’s cooling towers, which exposed the people to the bacteria via the air conditioning system.

Some things never change.

According to the CDC report, issued in May, most cases in the last 15 years were attributed to exposure to Legionella-contaminated potable water, frequently in aerosol form. This sort of exposure can occur from air conditioners, showers, decorative fountains, humidifiers and other places where running or falling water creates a spray that can be inhaled.

Legionella is not the only infectious agent that can multiply in water systems and cause outbreaks when water is aerosolized and inhaled. Outbreaks of non-tuberculosis Mycobacterium have also been traced to water in aerosol form. 

It’s time for a Safe Breathing Water Act.

While the Safe Drinking Water Act of 1974 and its subsequent amendments has significantly reduced the public’s exposure to ingested, infectious agents, such as viruses and harmful bacteria and chemicals, the crisis in Flint, Michigan has shown us that gaps in public health protection remain.

What was not well understood at the time of the Safe Drinking Water Act is that the pipes through which water is conveyed may serve as incubators for some bacteria, a number of which can cause illness if aerosols containing these bacteria are inhaled. 

Today bacterial amplification and exposure processes are better understood. We have also identified practices that can minimize chances of bacterial occurrence, such as  maintaining appropriate disinfection concentrations, keeping levels of nutrients (including those that can be released via corrosion) low and reducing leaks.

It is time to consider amending the Safe Drinking Water Act to include a “safe breathing water” provisions, which would incorporate our best knowledge and practice to reduce the public’s risk of inhaling Legionella, Mycobacteria and other respiratory pathogens that can be amplified in water systems and transmitted in aerosol form. 

As decades of public health engineering practice have shown, prevention is more effective when implemented closer to the source of the problem. So A Safe Breathing Water Act would include closer control of distribution systems and building piping, as well as restrictions on how systems with the potential to generate large volumes of aerosol are managed. 

It would also require licensing those who are responsible for maintaining water quality in large buildings. And buildings, with licensed operators, could be allowed to engage in local treatment without being considered public water systems. The act would set water quality contaminant limits that can be monitored and enforced at end-user taps and intakes of aerosol-generating equipment so as to protect not just people who drink water but also those who unwittingly breathe it as an aerosol.

This would be a suitable recognition of the lessons we’ve learned in the course of 40 years since the mysterious outbreak in Philadelphia made us reconsider all the ways we are exposed to water. 

A (Baby) Step Towards One Water

As even high school students know these days, the concept of the hydrologic cycle underlies all of what we do as environmental engineering practitioners and educators http://voices.nationalgeographic.com/2014/03/19/the-urban-water-cycle-sustaining-our-modern-cities/.  There are several key engineered systems in the urban water cycle:

  • Water supply storage & conveyance
  • Water treatment plant
  • Finished water storage & distribution 
  • Sewer and stormwater collection system
  • Wastewater (and stormwater) treatment plants
  • Effluent discharge structure


Historically in the US, in most places, different agencies sprung up to manage the “water” and the “wastewater/stormwater” sides of this cycle.  It is obvious however that everything is connected to everything else per Barry Commoner’s First Law of Ecology. There are a few cities that have progressively realized that “water is water” and developed a single agency to manage both sides of the urban cycle.  I am glad to live in one such place, where Philadelphia Water is a unified agency handling drinking water, wastewater, and stormwater.  

At the professional level in the US, we have had multiple different organizations work in different subsets of the engineered water cycle.  The American Water Works Association (AWWA) historically has worked in the water supply, treatment and distribution sectors.  The Water Environment Federation (WEF) has worked on the sewerage collection, wastewater treatment and disposal sectors.  More recently with the growth of planned wastewater reuse (including for drinking water supply), the Water Reuse Association (WRA) has worked in this sector.

Internationally, there is a more rational picture.  In the early 2000’s, realizing that “water is water”, the International Water Association (IWA) was formed from predecessors separately organizing the wastewater and water supply & treatment sectors.

Each of the US organizations has begat parallel foundations to conduct research programs in its areas of interest: the Water Research Foundation (formerly the American Water Works Research Foundation, the Water Environment Research Foundation, and the Water Reuse Research Foundation.  Earlier this month, in a baby step towards recognizing “one water”, the latter two foundations merged to form the Water Environment & Reuse Foundation, cleverly maintaining the acronym WERF. They are to be congratulated for this, and should be inspired to go many steps further.

In reality it is high time for the organizations and foundations to take the big step.  As someone who works in the areas of disinfection and microbial risk assessment, it has long been obvious to me that there is no big qualitative difference between “dirty” water and “clean” water (some in the industry like to use the terms “clean” water and “cleaner” water).  We really need one single US association and one single US foundation.  It is time for the US Water Association and the US Water Research Foundation!  That would really align the structure of the profession with the structure of what we work on.  

Of course there also needs to be unification of the federal legislative structure governing the overall sector – and I may devote a later piece to this.

Thoughts on Flint, Michigan

The water crisis in Flint, Michigan had once again highlighted the fact that water distribution systems, including the portion within individual buildings (which are generally the responsibility of property owners), are not inert.  In the US, water utilities are obliged to produce water that is acceptable for drinking (and other uses) at the consumers taps

Without getting into the politics, as someone who has done a lot of work in water treatment, and water chemistry, I have a number of questions:

  1. A basic measure of the stability of water is the corrosion (or stability) index.  I have not seen basic data on the raw water basic chemistry of the Flint River, nor the chemistry of the major species (alkalinity, hardness, pH, sulfate, chlorides) after treatment.  General Motors apparently went off the Flint Water supply due to high chloride levels (http://www.freep.com/story/news/local/michigan/2015/10/10/missed-opportunities-flint-water-crisis/73688428/).  For quite some time, the concept of stability indices (Langelier, Ryznar, Larson Ratio, etc) have been well known as tools to assess the aggressiveness (corrosivity) of a water.  For example, see this paper from 1980 (Millette, James R., Arthur F. Hammonds, Michael F. Pansing, Edward C. Hansen, and Patrick J. Clark. 1980. “Aggressive Water: Assessing the Extent of the Problem”. Journal (american Water Works Association) 72 (5). American Water Works Association: 262–66. http://www.jstor.org/stable/41270478.)  There is no single universal tool as pointed out by Marc Edwards in his important review in 2001(McNeill, Laurie S., and Marc Edwards. 2001. “Iron Pipe Corrosion in Distribution Systems.”  Journal of the American Water Works Association 93 (7):88-100.) 
  2. It seems clear now that as early as March 2015, a consultants report was issued in which the addition of corrosion control chemicals was advised (http://www.freep.com/story/news/local/michigan/flint-water-crisis/2016/01/21/flint-red-flag-2015-report-urged-corrosion-control/79119240/).  

    The full report from Veolia is online and has a suite of important and prioritized recommendations to take.  The response of this in terms of decisions to take or not to take action will be interesting to watch. However the focus of this report was NOT corrosion control, as exemplified in this quote: 

    • “The primary focus of this study was to assure compliance with the TTHM limits. That is not the only problem facing the city and its customers though. Many people are frustrated and naturally concerned by the discoloration of the water with what primarily appears to be iron from the old unlined cast iron pipes. “

  3. In the absence of corrosion control, one would expect that the solubilization of iron would cause a decrease in the chlorine residual.  Rhodes Trussell reviews the important relationships between corrosion, residual, and disinfection byproduct formation (http://www.awwa.org/publications/journal-awwa/abstract/articleid/13992/issueid/33528176.aspx?getfile=/documents/dcdfiles/13992/waternet.0049164.pdf).  Either no action was taken if the chlorine residual sampled in the distribution system was noticed to drop from previous levels, or the chlorine dose was boosted, and potentially resulted in increased disinfection byproduct formation.  Given that Flint had apparent concerns about compliance with TTHM levels, they may have been reluctant to increase residual.  It would be interesting to see lab data sheets for chlorine residual measurements in the distribution system before and after the switchover to Flint River water.
  4. If the chlorine residual dropped, then microbial levels in the distribution system could have increased.  Some, but not many, utilities measure heterotrophic plate count bacteria (HPC) in the distribution system.  I would expect their levels to have increased with a drop in residual.
  5. While the connection between the elevation of the Legionella case count subsequent to the switchover is possible, a direct connection may never be known because of the absence of samples from many of the clinical cases.  Frequently a genetic match between clinical isolates and environmental isolates is deemed necessary to make a definitive connection.

I will post subsequent thoughts and comments as they develop.