Are hidden dangers lurking in your airplane's water system?

Aviation International News » August 2001
May 21, 2008, 6:31 AM

Water. It’s rather simple stuff really. Two parts hydrogen and one part oxygen, bound together by positive and negative electrical charges. Pure and clean. Turn the tap and out it comes. So simple we often take it for granted. But should we?

Just how safe is the drinking water on the typical business jet? The answer is “usually pretty safe,” provided it meets the U.S. Environmental Protection Agency’s standards, and the fact is that drinking water from many U.S. municipalities surpasses them.

Crews topping off their aircraft’s potable water system at their own hangar, or at an FBO in the U.S. or Canada, can be fairly certain that the water meets U.S. standards and is safe to drink. But what if the water is coming aboard from a place where standards are not so carefully met? There are places in the world where there are no standards for drinking water, and others where existing standards are often blatantly disregarded.

So how does a crew ensure that the drinking water aboard the aircraft is truly potable? The glib answer is “bottled water.” Glib, and also wrong and impractical. First, despite the assurances of such advocates as the “Bottled Water Web” (www.bottledwaterweb.com), bottled water is often no safer than that coming out of the local tap. Tokyo Narita International Airport’s Quarantine Office of the Ministry of Health, Labor and Welfare conducts regular inspections of drinking water on aircraft and in water-supply trucks. In a recent study, the office found that “all samples from water-supply trucks and containers satisfied the guidelines. But 58 samples (25.4 percent) of water from tanks in 29 aircraft and three samples (23.1 percent) of bottled water received unsatisfactory assessments. To be precise, the number of bacteria exceeded the standard value in 55 samples (24.1 percent) from 28 aircraft, and pH levels exceeded the standard range in four samples (1.6 percent) from two aircraft.”

In addition, “Escherichia coli [E. coli] was detected in one sample from one aircraft.” For those who may not know, this particularly nasty bacteria is an indicator of fecal contamination. At its least aggressive, the victim has stomach cramps and diarrhea. At its worst, the victim’s liver may cease functioning, resulting in death. Children and the elderly are particularly susceptible to this bacteria.

Many business jet crews trust those delivering their drinking water, and others assume that the single-stage carbon filter through which water enters the aircraft is sufficient to ensure potability. Both are wrong.

First, trusting that the water delivered is safe might require a considerable amount of trust. Last year, Britain’s Public Health Laboratory Services agency conducted a survey of aircraft drinking water at 13 airports and from aircraft operated by 21 airlines, and the result was hardly encouraging. There was a 9-percent fail rate. In fact, 15 percent of 850 samples of water from drinking fountains or taps on board aircraft showed the presence of “potentially harmful material, including food-poisoning bacteria and fecal traces.”

Second, the carbon filter is good for no more than filtering out sediment and the chlorine typical of most municipal water supplies. And if not replaced regularly, the carbon filter itself may become a bacterial breeding ground.

Ensuring Safe Drinking Water

To ensure safe drinking water most aircraft manufacturers begin with recommendations for a regular change of the carbon filter and extensive flush cleaning of the entire water system. Gulfstream Aerospace, for example, suggests doing both at the 3,000-gal or 3,000-hr point, whichever comes first. The flush is done by over-filling the system with a solution of 10 fluid ounces of 5 percent chlorine per 40 gal of water. This is allowed to stand for four hours. The system is then drained and rinsed three times with fresh water. Then it is filled a fourth time with clean water and allowed to sit for eight hours. That water is drained again and the system is ready to be refilled and used.

As to ensuring that the water delivered for onboard use is safe for drinking, FBOs and caterers alike report that many customers are now filling their potable water tanks with bottled water. Some even insist on such import brands as Evian. And many crews planning to be abroad for an extended period will buy a sufficient supply of bottled water to replenish the aircraft’s potable water system.

According to experts on safe drinking water, there is no portable kit to test water for dangerous bacteria, although kits are available that will indicate the presence of chlorine. In extreme cases, sediment will be readily visible as it settles in a clear glass container. But since the carbon filters that are standard equipment on business aircraft will deal with these two contaminants, it hardly seems worth the effort to test for chlorine or sediment.

There are water purification kits, available from outdoor sporting goods stores and some cautious business travelers are carrying them.

Some industry experts recommend that rather than allowing potable water tanks to be filled with water that may be contaminated, it is better to buy a reliable brand of bottled water for use in drinking and cooking until a destination is reached where a reliable source of potable water is available.

Zapping Bugs with UV

But many of the ultra-long-range business jets today are being equipped with a water-filtration/purification system that will disinfect and filter water. International Water Guard, based in Burnaby, British Columbia, is now offering an entire water system for larger aircraft that includes tank, upstream filtration (to eliminate sediment and unpleasant tastes and odors) and ultraviolet (UV) radiation to destroy microorganisms.

The Canadian company claims its UV disinfecting systems are now aboard more than 500 business aircraft. International Water Guard is currently in the process of installing its first circulating potable water system. It is being put into a Global Express being completed at The Jet Center in Van Nuys, Calif. “It’s the first airplane with the complete system,” according to International Water Guard’s Rick Steadman. The system features:

•    two water circulation pumps,

•    a 42-gal lightweight, titanium, conformal tank placed to the left of the passenger door, within the curve of the fuselage and behind the crew closet,

•    an NPS-A3 ultraviolet water treatment chamber,

•    an upstream, replaceable carbon filter, and

•    a monitoring unit to determine the effective operation of the UV chamber.

It offers a number of advantages over the conventional water system, not the least of which is a weight saving of about 150 lb. And, noted Steadman, because the water is constantly moving through the system, there’s no danger of it freezing at high altitudes.

The old NPS-A2 UV from International Water Guard is being replaced by the NPS-A3, which has both the replaceable carbon filter and UV chamber in the same box.

Steadman said the NPS-A2 and NPS-A3 both meet water treatment standards set by the Ann Arbor, Mich.-based National Sanitation Foundation. Class A is the most stringent standard for UV disinfection of potable water and sets a minimum ultraviolet dosage of 38,000 microwatt-seconds per square centimeter. Steadman said the NPS-A3 delivers a minimum dosage of 48,000 microwatt-seconds per square centimeter, and the lamp has a life of 3,000 hr. It is, according to International Water Guard, “A proven process [that] destroys harmful bacterial and viruses,” including such emerging health threats as E. coli, the bacteria that infected the water system in Walkerton, Ontario, last year. It is also effective against cryptosporidium, the waterborne organism that caused more than 100 deaths in Milwaukee in 1993.

New System for GV-SP

At Gulfstream Aerospace, the company has long since discarded the old bleed-air pressure system and used an air compressor for the potable water systems on GIV-SPs and GVs, but still uses the older, heavier pressure tanks. On the new GV-SP, however, the system will be designed to use weight-saving conformal tanks. A strainer and carbon filter are standard, but the International Water Guard UV purification unit will be offered as an option.

Randy Grovenstein, project engineer for completions at the company’s Savannah, Ga. facilities, said demand for the UV purification unit, once running at about 40 percent, has dropped off in recent months to about 20 or 25 percent.

He added that the new GV-SP is being designed with a potable water system “in accordance with FDA standards as a guideline, and that meets federal regulations for drinking water.”

While Boeing Business Jets is not in the business of providing interior completions for BBJ buyers, Dayton Robinson, director of oversight for completions, said the company is encouraging customers to look at an unpressurized water system.

As to water purification, Boeing has chosen to install both a carbon filter and a UV disinfectant chamber on its demonstrator BBJs. Expecting a wide range of mission requirements, the company has a 100-gal potable water tank on the first demonstrator and a 60-gal tank on the second to supplement the 60-gal tank that is standard on the airliner version. The second BBJ will use an electric water pump, rather than bleed air, to maintain a constant-pressure flow. “And since the water is constantly moving,” said Robinson, “we don’t have to wrap heat tape around the pipes.”

More interesting is the recycled water shower on each of the BBJ demonstrators, which brings up other concerns about potability. The shower systems include downstream filtration packs, conductivity and turbidity monitors, compressor and pumps, vacuum and pressure tanks, ultraviolet disinfectant chamber and water heater. Aquajet, a Woodway, Texas company, is producing the systems for business aircraft and has already obtained STC approval.

As to the water that has been recycled, there is no question that it is safe, said Robinson. As for the taste, he said, “You couldn’t tell the difference between [the original] potable water and recycled water.”

The recycled water shower can be tied to the standard potable water system to allow a resupply of unrecycled water when desired. Or it may be self-contained, operating on a supply of as little as five gallons of water.

Robinson did admit that a large number of BBJ customers are concerned about the safety of drinking water, particularly that obtained at destinations outside the U.S. And many are opting for an infrared water purification system. “Where the airplane goes, there are certain to be differing standards, and therein lies the concern,” he concluded.

Erica Sheward, sales director for Castle Kitchens Executive Catering in London, long an advocate of safe food-handling procedures aboard business aircraft, is equally adamant about ensuring the safety of drinking water, as well as ice that is delivered to the aircraft. Some bacteria, she noted, thrive quite nicely in cold, even frozen, environments.

Emphasizing the need to ensure safe drinking water aboard aircraft, Sheward will be speaking on that subject at the World Food Safety Conference being organized by the Michigan-based National Safety Foundation in October in Palma, Mallorca.

The safety of water aboard the airplane is and should always be a major concern, said Sheward. “To treat it lightly is to take your own health and that of others lightly.”

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