New CDC Waterborne Illness Study Reinforces Our U.S. Water Stresses

I was washing dishes in the kitchen recently when I noticed a fine mist that the sunlight caught just right. It was beautiful, but in my line of work, also reminded me of danger. Those water droplets swirling through the air can carry waterborne pathogens such as Legionella. ? We usually think about the Legionella threat in terms of hospitals and buildings. But the Legionella threat can impact residential water systems too.

I bring this up on World Water Day because last week, the U.S. Centers for Disease Control (CDC) released a report of waterborne disease outbreaks associated with drinking water systems. Legionella-associated outbreaks increased over the study period from 2015 - 2020, with 786 reported illnesses, 544 hospitalizations, and 86 deaths. That’s just what we know. Legionnaire’s Disease is highly underdiagnosed, with a recent NASEM report estimating that between 50,000 to 70,000 cases of the disease occur per year.??

Another word for that mist I saw is aerosolization, which is typically how the Legionella bacteria infects people. In single-family homes, water doesn’t stay in the system long enough to allow for growth.? However, if my home water had been standing in pipes for a long time due to pipe-oversizing or a period of no building use--especially at approximate water temperatures between 70F-120F, then the Legionella bacteria could quickly grow in these conditions. When high concentrations become aerosolized--most often in the shower, but also possibly from a sink --we can breathe it in as a direct pathway into our lungs. It is that easy.?

The CDC identified premise plumbing as a key factor contributing to these outbreaks and noted the necessity of comprehensive water management programs to mitigate risk.

As it happens, my employer IAPMO has just published a well-received Manual of Recommended Construction Practices for Potable Water. Here are some of the best practices IAPMO research identified for construction professionals:?

1. Delaying the filling of the water system until absolutely necessary can limit contamination risk and conserve water. The manual recommends either conducting pressure testing with air or dry nitrogen instead of water, using temporary water supply systems for construction purposes, or having the installing contractor flush the entire system at least weekly.

1. Water age is the first water quality parameter plumbing professionals should be aware of and minimize. Figuring out the basics can be overwhelming, but fortunately, the “Manual of Water Quality for Plumbing Industry Professionals and Building Managers” is conveniently located as an annex!??

1. Develop a formal construction water management program to ensure water safety and quality from the construction phase through to the building's occupancy.??

1. Take practical and actionable steps in minimizing water hazard to reduce water age via the manual’s fifteen helpful tables and figures.

1. Complete an initial system flush at high velocities to remove sediments, debris, and other contaminants introduced during construction.

1. Become aware of special considerations for building types such as healthcare or multifamily such as dissolved inorganics or disinfectant byproducts.

1. Identify water quality parameters, such as Legionella or disinfection levels, that have the greatest impact on water safety during construction, both for the installers and for the eventual building occupants.?

1. Consider engaging professionals who have acquired certification in the ASSE/IAPMO/ANSI 12000 Series, such as the ASSE/IAPMO/ANSI 12061 Water Quality Program for?Plumbers? or the ASSE/IAPMO/ANSI 12080, Professional Qualifications Standard for Legionella Water Safety and Management Personnel

1. Follow best practices for reopening closed buildings, including disinfecting the water system before the building is occupied to address all biofilms and potential pathogens. A good resource is the Recommended Practices for the Safe Closure and Reopening of Building Water Systems from IAPMO and the American Water Works Association (AWWA).?

1. Hot water systems are of heightened importance because their temperature has the potential to contribute to pathogen growth. This is why IAPMO has initiated a hot water recirculation task group to develop a manual to improve the design, installation, commissioning, and maintenance of these systems.??

What about everyday users who have concerns about their home systems? The good news is that single-family homes have a lower risk profile, but there are situations that warrant extra attention, such as when the occupants are elderly or immunocompromised. When I interviewed Dr. Janet Stout on the IAPMO podcast, she recommended point-of-use filters on the most frequently used shower and faucets, but also noted that simply boiling water can also control pathogen exposure.?

In the past year, we’ve seen drinking water headlines go well beyond the Flint, Michigan story we all know. The incidence of PFAs, the ongoing lead pipe issue, and waterborne illnesses demonstrate that our water in the U.S. is stressed.? Plastic bottled water has concerns too, as gallon-for-gallon they can cost almost 2000 times more than tap water and can include 240,000 detectable plastic fragments in them.? World Water Day reminds us of the global need for safe water. I want to use today to remind everyone that safe water literally starts at home.??