Until it becomes an inflight necessity, most passengers probably give the lavatory little thought. For air carriers and OEMs, however, the lavatory is becoming a focal point for finding additional weight-savings and cabin space, not to mention reduced maintenance.

“Modern airliner lavatories will incorporate more lighter-weight structures, LED lighting and antibacterial surface coatings, as well as germicidal ultraviolet lighting,” says Gary Weissel, managing officer of Atlanta-based Tronos Aviation Consulting. He says companies also are looking at automatic flushing, but “the main advances will have more to do with improved hygiene and antibacterial technology. Along with that is [flushing] noise and weight reduction.”

Weissel points out that designs for aircraft lavatories are moving toward smaller, sculpted units, which create space for additional seat rows. “This is especially true for narrowbodied aircraft,” he says, citing the Advanced Lavatory, a Rockwell Collins product designed for the Boeing 737. “It allows an additional row of seats, with a pitch of about 30 in., behind the over-wing exit.” 

Lufthansa Technik is working with Diehl Aerosystems, which designed a combination lavatory/galley to Lufthansa Technik specs. Announced in March, the unit, known as the High-Density Solution, is available only from the Hamburg-headquartered MRO, according to Oliver Rodrigues,  Lufthansa Technik’s sales manager for High-Density Solutions.

“By combining the lavatory and galley into one module, we created extra space in the main cabin, which the airlines can use to provide more comfortable seating or additional rows to increase revenues,” he says. “One extra row will keep the seat pitch as-is, while more rows would have a slight impact. But according to seat type, the minimum seat pitch will be 29 in.”

​Rodrigues points out that while “no new materials were used in the unit’s construction,” both Diehl Aerospace and Lufthansa Technik were able to “optimize the complete design,” resulting in a 150-kg (330-lb.) weight reduction, compared to similar products.

Initially, the High-Density Solution is being certified for the Airbus A320, with entry into service slated for February 2018, but the concept could find its way to other platforms.

“Besides the A320 family, there are many ideas for the High-Density Solution,” Rodrigues stresses. “We are working on some others that we expect to bring to market soon.”

He reports that the primary market will be retrofit, although the solution also will be available as a post-delivery modification. “We do see a trend for more High-Density Solutions. Airlines can save a lot of money and will have a quick return on investment, which is possible within 18 months.”

While logic suggests that low-cost carriers should be the main customer base for the High-Density Solution, Rodrigues says the system has also generated considerable interest from legacy airlines. “Every second request we are getting for information is from legacy carriers,” he says.

Any lavatory’s most important component is the toilet. For airlines, that component’s acquisition cost, along with reliability and weight, are the primary areas of concern, explains David Conrad, vice president, of sales, marketing and customer support for Zodiac Water and Waste Aero Systems—a Carson, California-based business unit of Zodiac Aerosystems.

“Reliability is tied to lower maintenance costs, so parts such as the flush valve have to be designed for less frequent removal,” Conrad says. “Airlines are also sensitive to weight, so we are moving away from the all-metal legacy toilets to plastic and carbon composites, which provide the durability of metal while cutting down on weight.”

Zodiac has incorporated those materials trends in its Revolution toilet, introduced in 2014. At 9.5 lb., it provides at least some weight savings compared to similar products.

“The toilet’s reliability is a work in progress,” Conrad notes. “Our lead customer, an international carrier, has had 78 Revolution toilets in service on its narrowbody fleet since 2014, with no reported failures to date.”

Conrad says the Revolution toilet has been designed for low water usage while providing a clean flush. “When we talked to the airlines, lower water use was one of their major concerns, because less water means less weight,” he says. “Older vacuum flush toilets use 7-7.5 oz. per flush, while the Revolution toilet uses 5-5.5 oz.—a savings of 33%.”

The Revolution toilet garnered the Crystal Cabin Award at this year’s Aircraft Interiors Expo in Hamburg. Currently, it is certified on the A320 family and the Boeing 737, 747, 767 and 777 families, says to Conrad. Zodiac is considering regional jets as the toilet’s next application.

Embraer’s focus in designing the lavatory for the new E-Jets E2 regional jets was to “maximize space and minimize maintenance and operational costs,” says Andre Stein, director of industry analysis and product strategy/market intelligence for Embraer Commercial Aviation.

“Robustness is a main driver for the entire E-Jets E2 project. For example, for structures under wet areas—like the lavatory, which could be prone to corrosion—we have used titanium,” Stein says. “We have also used advanced acrylic polymers and stainless steel in areas such as the sink.”

Stein says Embraer is offering an option for infrared touchless faucets and flushing as well. The touchless faucet, he explains, can deliver a 25% water savings compared to a manual faucet, while the flush unit can save 50% of rinse water compared to similar products. “Both items are part of a ‘touchless kit,’ and we foresee a good market penetration for this feature,” he notes.

“The touchless kit and conventional options conform to the very stringent durability requirements for all options on the E-Jets E2,” including those for the lavatory, Stein asserts. “For example, the toilet features a modular construction, with tool-less maintenance—including quarter dzus [fasteners] and quick-disconnect clamps. It also delivers a 50% weight- savings compared to the E1 [aircraft family] toilet, as well as most current toilet units on the market.”

Stein reports that the improvements to the lavatory are the result of airline experience with those on the E1 family. “That made it easier for us to understand where to improve even small details of the lavatory for smoother operations.  For example, we changed the direction of one air exhaust grill. It had a tendency to accumulate dirt, requiring more frequent cleaning. Having the grill facing down rather than up minimized that accumulation,” he says. “We also reduced the number of openings where a foreign object could be placed, reducing the requirements for tamper-proof tape and security checks at every [aircraft] turnaround.”

Asked if the new regional airliner lavatories have incorporated design elements from those on Embraer’s business jets, Stein says, “They are very different markets, but the expertise to develop and integrate systems, like water and waste, are the same.”

Modern lavatory designs are actually less maintenance-intensive, according to Earl Diamond, CEO of Avianor, a Montreal-based specialist in airliner interior modifications and retrofits. “New designs are ‘modern,’ which equates to fewer parts, and those parts will be easier to remove and replace than those on older equipment. Also, the newer lavatories are more electronics-intensive,” which, he says, means less maintenance.

Do the new lavatories coming on the market mean a future wave of retrofit activity? That is highly dependent on the age of the aircraft and long-term fleet planning.

“I expect there will be more touchless service items designed into the new lavatories,” says Michael Planey of HMPlaney Consultants, a travel technology consultancy. “However, this technology will likely be only available on certain aircraft types, and may not be an option for retrofit on certain older aircraft types due to electrical power restrictions.”

He thinks most of the coming design and technology innovations likely will find their way as line-fit items on new aircraft, although some will be available for retrofit within aircraft families such as the A320 or the 737. 

Avianor’s Diamond notes that as airlines operate their fleets for longer periods, they may at some point opt to upgrade the lavatories. “Usually, that would be part of a fleet-wide, cabin modernization program,” he says.