The ADWR: An Introduction 

Many might be surprised to find that air carriers (while it is convention to call them “airlines,” this study chooses to use the proper legal nomenclature, which is “air carrier.” An air carrier is responsible for ensuring all aircrafts it operates comply with the ADWR. See key definitions above) are required by the EPA to clean out the water tanks on their aircrafts – which is where the water used for hand washing in the lavatories and for making beverages like tea and coffee comes from – only one to four times per year. This lax requirement raises the question: how safe is the water onboard? 

The safety of water available on flights is jointly regulated by three government agencies: the Food and Drug Administration (FDA), the Federal Aviation Administration (FAA) and the Environmental Protection Agency (EPA). The EPA, FDA, and FAA draw their regulatory powers from the Aircraft Drinking Water Rule (ADWR, 40 CFR Part 140, Subpart X), which was implemented in 2011. 

The FDA regulates water (including ice) used in food and drink preparation, in addition to regulating the safety of the points where aircrafts obtain water at airports (such as water trucks, carts, and hoses) so as to ensure that the water transfer process will not result in any contamination. The ADWR specifies that the FDA draws its regulatory powers from the Control of Communicable Diseases regulations (21 CFR 1240), though the FDA also draws regulatory powers for water safety on aircraft from Interstate Conveyance Sanitation regulations (21 CFR 1250). The FDA retains the power to conduct their own routine inspections with or without EPA intervention. If a watering point does not meet FDA approval, the FDA has the authority to bar air carriers from obtaining water from that source. 

The FAA regulates the operation and maintenance of potable – in other words, safe to drink – water systems on aircrafts. These “O&M” plans are submitted by air carriers and must be approved by the FAA. These plans are discussed at length in this study. 

Finally, the EPA is responsible for ensuring the safety and cleanliness of the water once it is actually onboard. 

The authors of this study found the distinctions between these roles somewhat unclear. To help clarify, we included a definition of the agencies role in the question form we sent to EPA representatives.

The ADWR: A Brief Background 

The Aircraft Drinking Water Rule was implemented to ensure that a safe supply of drinking water is available to passengers and crew on board. Though the rule took hold in 2011, the motivation to create the ADWR dates back to the summer of 2004, when the EPA tested the water quality on 158 aircraft across 7 airports as part of enforcement activities. The EPA conducted a follow-up study (this time analyzing 169 aircraft from 20 different airports) in November of 2004, and found that 17 percent tested positive for coliform. The results also indicated that all aircraft public water systems tested were out of compliance with the National Primary Drinking Water Regulations (NPDWRs). 

Coliform bacteria are commonly found in soil, surface water, and feces. Most kinds of coliform bacteria are harmless to humans but a few can cause severe waterborne diseases. So, even though the presence of coliform does not guarantee that the water is unsafe to drink, coliforms are often considered “indicator organisms,” because their presence indicates the potential for other disease-causing bacteria to also grow in the water. 

These 2004 findings prompted the EPA to develop a separate set of mandates – the ADWR – for water systems on aircraft, since the NPDWRs were designed with “stationary public water systems” in mind, such as the water systems in schools and restaurants. Aircraft operate under unique conditions: they are mobile by nature and may pump drinking water into water tanks from several different locations, including water sources from international locations. Water onboard aircraft also depends on the safety of the equipment that transfers water onto the aircraft, such as water cabinets, trucks, carts, and hoses. 

Thus, the EPA needed to construct separate mandates for the unique nature of aircraft. At the time, 12 national airlines announced that they would support the EPA in its attempt to create new safety measures for the water on aircraft (these were Alaska Airlines, Aloha Airlines, American Airlines, America West, ATA Airlines, Continental Airlines, Hawaiian Airlines, Jet Blue, Midwest Airlines, Northwest Airlines, United Airlines and US Airways.) More airlines followed suit. The EPA then placed 45 air carriers under Administrative Orders on Consent (AOCs). Air carriers were subject to the NPDWRs or  the AOCs (2005 – 2007) to resolve non-compliance with the NDPWRs until ADWR became effective on October 19, 2011. It was estimated that a total of 63 air carriers and 7,327 aircraft public water systems were covered by the proposal. Today, the ADWR falls The National Primary Drinking Water Regulations, Subpart X. In the words of the EPA, the ADWR “tailor[s] the NPDWRs to the unique characteristics of aircraft water systems.”

During the development of the ADWR, the public was permitted to submit comments and feedback on the proposed rule. The EPA also hosted public meetings in June 2005, January 2006, and March 2007, which were attended by a slew of stakeholders including air carriers, flight attendants, other federal agencies, environmental groups, and more. 

Not all stakeholders involved the air carrier industry saw eye to eye with the proposed regulations. 

Representatives from the Air Line Pilots Association, International, expressed concern that, while the proposal stipulated that public notice of a coliform- or E.Coli- positive result would be required, this public notice would not be provided to persons who may have already been sickened before the discovery of the water sample. Representatives suggested that, at a minimum, crewmembers and passengers onboard the aircraft within 14 days prior to the coliform-positive or E. Coli-positive sample should also be notified. This common-sense suggestion did not make it to the final version of the ADWR. According to the current ADWR, “passengers and crew that were on previous flights of the same aircraft are not required to be notified, even if the situation first developed at the time they were on the aircraft [emphasis ours].” 

The final version of the ADWR did, however, take another of their suggestions into account. Air Line Pilots Association representatives noted that the proposed rule did not outline protocol for what they called “identified problems.” While the proposed rule provided instructions for routine samples and monitoring, it did not provide clear protocols on what to do if crewmembers or passengers have reason to believe water onboard may be tainted by observing unusual characteristics of its taste, smell, color; or due to cases of sickness from those on board. The current ADWR requires air carriers to outline their protocol when cases of these “identified problems” arise during a self-inspection of the aircraft water system in their O&M plans [emphasis ours]. It is important to keep in mind that air carrier “self-inspections” are mandatory only once every five years. 

The reps also suggested that the provision of medical assistance be included when air carriers are faced with an “identified problem.” This suggestion did not make it into the final version of the rule.

The Air Transport Association of America (ATA) (now known by the name “Airlines For America”) expressed their concerns with the proposed rule as well. The ATA had worked in consultation with the EPA to develop the ADWR and had provided the EPA with a summary and analysis of water quality sampling data, which was collected from eight of the ATA’s member air carriers between October 12, 2007 and April 7, 2008. The ATA had also provided sampling data from ATA carriers for the entirety of 2008 and for January through March, 2009. 

Altogether, the ATA collected more than 14,000 water samples and concluded that “aircraft drinking water poses minimal health risks to passengers and crew.” Their reasoning was that water samples taken from the galley are more representative of the quality of water on aircraft than samples taken from the lavatory, where bacteriological contamination is more likely. From data they collected between 2008 and 2009, for example, only .6 percent of their water samples from the galley came back with coliform-positive results. Therefore, the ATA suggested that reliance on lavatory water testing would constitute an unnecessary administrative and cost burden for air carriers. (According to the then-proposal of the rule, the EPA considered water for “human consumption” to include water used for drinking and food preparation as well as water for brushing teeth and hand washing, two activities which are typically done in lavatories. This interpretation made it into the final rule, and today air carriers are required to test the safety of their water from both the galley and the lavatory.)

The ATA also took issue with the proposed frequency of routine disinfection and flushing, and pushed for less frequent disinfection and flushing schedules. The ATA found “no statistically significant difference” between coliform-positive results from air carriers that disinfected on a 180-day scheduel (3.3 percent) and from air carriers who performed disinfection procedures every 90 days (3.8 percent). “The 90-day disinfection schedule is especially disproportionate to the risks when one considers the costs associated with such frequent disinfection,” the report advised. 

The ADWR: An Overview 

Coliform Sampling, E. Coli Sampling, and Disinfection & Flushing Procedures 

Under the ADWR, air carriers are required to take water samples from their water tanks in order to test for the presence of coliform bacteria and/or E. Coli bacteria (see the FAQ for more details on coliform). Air carriers only need to discover whether either of those bacteria are present in the water sample – a determination of the density of these bacteria is not required. 

The standard sample volume is 100mL. One sample must be taken from the galley, and another sample must be taken from the lavatory. If an aircraft does not have both a galley and a lavatory on board, then two samples from a single tap may be analyzed. The time from sample collection to initiation of the sampling analysis must not exceed 30 hours. All water samples are required to be analysed by EPA-certified or State-certified laboratories. 

Air carriers are also required to disinfect and flush (D&F) out their water tanks. Routine coliform sampling cannot be collected within 72 hours of disinfection and flushing.)

It is important to note that if an aircraft manufacturer provides its own recommendations for the frequency of disinfection and flushing, then air carriers may follow the manufacturer’s recommendation. When such recommendations are not available, however, the EPA provides the following recommendations for the frequency at which air carriers are required to perform coliform sampling tests and D&F can be seen below. 

An air carrier must choose one of the four options above for its aircraft. For example, if an air carrier decides to disinfect and flush out its water tank four times per year (quarterly), then it must collect and analyze water samples to test for the presence of coliform at least once per year. On the other hand, if an air carrier chooses to D&F only once per year, then it must collect and analyze water samples at least 12 times per year. An air carrier is welcome to do more than what the EPA asks (performing D&F procedures four times per year but collecting water samples four times a year, for example). However, an air carrier can never perform less than the minimum frequency recommended by the EPA. 

Operation and Maintenance Plans 

All air carriers must develop an FAA-approved O&M (operation and maintenance) plan for each aircraft listed under an air carrier’s inventory. More than one aircraft may be covered by the same plan. For example, if an air carrier owns Boeing 737s and 767s, it must create plans for each. If an air carrier owns only 737s, then only one O&M plan and one sampling plan are needed. 

The ADWR does not specify the exact products or disinfecting air carriers and aircraft must use to disinfect and flush their water tanks (it does, however, provide suggestions.) While there are several that are common across the industry, and while aircraft manufacturers often provide recommendations for cleaning and maintenance of the water tanks, each air carrier ultimately decides on their own strategy in their O&M plan. 

These plans must include details on:

1. Which FDA-approved watering points the air carrier plans to utilize
2. Procedures for disinfection and flushing (the disinfection frequency, type of disinfecting agent, disinfectant concentration to be used, and the disinfectant contact time, and flushing volume or flushing time must also be outlined)
3. Procedures for coliform sampling
4. Procedures for follow-up sampling
5. Procedures for training requirements of all personnel involved involved in aircraft water system operation 
6. Procedures for conducting self-inspections (this includes, but is not limited to, an inspection of the storage tank, fixtures, valves, and backflow prevention devices. A complete self-inspection of the aircraft water system is required at least once every 5 years.)
7. Procedures for safely boarding water onto the aircraft so as to avoid contamination (including procedures for ensuring that water that collected from outside of the U.S. is safe for human consumption. While water boarded from outside of the U.S. is outside the jurisdiction of the EPA and FDA – and therefore the ADWR – aircraft operators must ensure that the water is safe when the aircraft reaches U.S. soil) 
8. An explanation as to whether the aircraft water system can be physically disconnected or shut-off, or the flow of water otherwise prevented through the tap to the crew and passengers

See here and here for more information on the details that must be included in the O&M plans.

Air carriers do not need to submit these O&M plans to the EPA. However, the EPA reserves the right to request to see these plans at any time. In our survey, we asked the EPA to clarify whether their organization ever sees or needs to approve of these O&M plans. 

Notification to Passengers and Crew 

In order to be in compliance with the ADWR, air carriers must alert passengers and crew in the event that the water on board may be hazardous to human health.

The air carriers must also notify all passengers and crew if: 

1. Public access to the aircraft water system is restricted as a result of a routine, repeat, or follow-up sample that tested positive for coliform or E. Coli
2. The air carrier failed to perform the required routine D&F procedures or collect routine water samples for testing
3. The air carrier failed to collect follow-up samples upon the discovery of an E. Coli positive result
4. The air carrier failed to collect follow-up samples upon the discovery of a coliform positive result (but was E. Coli negative)
5. If the air carrier becomes aware of an E. Coli positive sample as a result of boarding water from a watering point that has not been approved by the FDA (or a watering point that generally does not meet National Primary Drinking Water Regulations, or a watering point that is deemed unsafe as per the standards set in the aircraft’s O&M plan)
6. If the air carrier becomes aware of a coliform-positive sample (but that is E. Coli negative) as a result of boarding water from a watering point that has not been approved by the FDA (or a watering point that generally does not meet National Primary Drinking Water Regulations, or a watering point that is deemed unsafe as per the standards set in the aircraft’s O&M plan)
7. The EPA Administrator, or air carrier, or crew determine that notification is necessary to protect public health

For scenarios 1 – 6, public notice must be prominently and conspicuously displayed in each lavatory on board. The notice must explicitly state that the water is non-potable, and should not be used for drinking, food and beverage preparation, hand or teeth washing, or “any other consumptive use.” Public notice must also be accessible to many populations. It is forbidden, for example, to use overly-technical language and very small print in a public notice. The notice must also take into consideration any non-English speaking persons on board. The ADWR guide recommends using an easily recognized symbol that indicates the water is non-potable. 

Public notice containing similar instructions must also be given to the crew and must be displayed in the galley. However, crew members additionally receive significantly more information than passengers for all six scenarios. For example, in scenario one, the crew is also informed of the cause of contamination, the contaminants found, the adverse effects the contaminant may have on human health, which populations can be at risk as a result of drinking water tainted with the contaminant, what the air carrier is doing to address the situation, and the expected time it will take to re-grant public access. A similar pattern is found in the following 5 scenarios. 

It is also significant to note that if the water system is physically cut off from passengers (such as by disconnecting the water and preventing it from flowing), or if water is only supplied to lavatory toilets and not to lavatory or galley taps, then only the crew needs to be notified of the above six scenarios. 

In scenario seven, the air carrier may choose to notify passengers in the form of a broadcast over the public announcement system, posting physical notice in conspicuous locations, a hand-delivery of the notice, or by any other method deemed appropriate and approved by the EPA administrator. 

Public notice must be initiated within 24 hours of the discovery of an E. Coli positive result and within 72 hours of a coliform positive (but E. Coli negative) result. Public notice must remain in place until water samples yield coliform negative results. A copy of the public notice does not need to be provided to the EPA, though an EPA administrator may request it at any time during a compliance audit. 

The EPA has provided templates of public notices. The EPA also must be informed of an instance in which public notice arises within 10 days of the event. Air carriers can do this by reporting to the Aircraft Compliance Reporting System (ARCS), a centralized, web-based data collection and management system created by the EPA. This database helps helps ADWR managers conduct regulatory program oversight. (See the FAQ for more information on the ARCS database.)

EPA Audits and Inspections

While air carriers are given freedom to self-monitor and self-inspect, the EPA may conduct compliance audits as deemed necessary. Any deficiencies found during the compliance audit must be addressed within 90 days. If the air carrier in question has not addressed the deficiency in question and the aircraft(s) are still being used to transport passengers, then the air carrier is in violation of the ADWR. 

The ADWR: Gaps in Regulation 

Despite these mandates, The Association of Flight Attendants (AFA) believes that not enough is being done to ensure the safety of water on aircrafts. 

“The Association of Flight Attendants-CWA pushed for [the ADWR] more than 15 years ago. The regulation gives broad discretion to airlines on how often they must test the water and flush the tanks. The Association of Flight Attendants does not believe this regulation goes far enough or is sufficiently enforced,” a representative told Business Insider in 2017. 

The Annual Airline Food Investigation with Health Ratings (2018-2019) performed by the Hunter College NYC Food Policy Center and Diet Detective came to a similar conclusion: “It’s probably best to avoid drinking water from the tap on a plane, which also means staying away from coffee and tea. Even though the EPA has instituted the Aircraft Drinking Water Rule (ADWR) to ‘ensure that safe and reliable drinking water is provided to aircraft passengers and crew,’ there are a couple of reliable researchers who believe there may be harmful bacteria in airline water,” wrote the Executive Director of the Hunter College NYC Food Policy Center, Charles Platkin, PhD, JD, MPH.

A 2015 study published by The International Journal of Environmental Research and Public Health found that “aircraft water supply tanks are conducive for microbial growth,” and that “the water service vehicle was a significant source of increased microbial load in aircraft.”

These remarks exemplify some of the gaps evident in the ADWR. As such, the Center wanted to find out how thoroughly the EPA ensures air carrier’s compliance with ADWR regulations.

Main Questions 

First, the rule relies on air carriers to both self-monitor and self-report. The Center wanted to find out:

• How does the EPA ensure self-reported data is accurate? 
• How does the EPA punish those who violate the ADWR?
• How does the EPA ensure that public notice in the case of contamination has been given?
• How does the EPA communicate and collaborate with the FAA, FDA, and airport authorities?
• Do EPA agents ever have to step in and investigate? 

Second, the Center was concerned about the nature of violations:

• Are some violations considered more severe than others? What exactly would be considered to make one  violation more severe than another? 
• Do air carriers incur monetary fines if they are repeat violators? 
• Are there any consequences associated with having multiple violations within a given time frame (i.e., one year, five years, …)?

The Center had other lingering questions: Why are tanks required to be cleaned only one to four times per year? How are foreign air carriers regulated, if at all? How does EPA ensure that vehicles that transport water into the water tanks on aircraft are properly cleaned? How does communication and collaboration among the three government agencies responsible for airline drinking water work, exactly? 

The Center conducted a survey with relevant stakeholders to find answers to the questions above.