For Delta’s some 3,000 daily flights, there are a lot of moving pieces that have to come together. Getting water on board is just one of the many processes that take place before you takeoff.

Each Delta plane is equipped with a tank system that holds anywhere from 38 gallons to 290 gallons of water, depending on fleet size and type.  This water is needed for hot tea and coffee made in the galleys, while regular drinking water is served from bottles. The on-board water system also supports sinks and commodes in the lavatories. The complex tank system keeps the water flowing through the taps. 

Before each departure, Delta makes sure that the plane has enough water to service its next trip. If it doesn’t, it’s time to fill up the tank.

But where does the water come from?

Delta sources local water from municipal water sources that have been approved by the Environmental Protection Agency (EPA) as a public water system, like the City of Atlanta at Hartsfield-Jackson International Airport. Providers are held to the EPA’s National Primary Drinking Water Standards and must meet them in order to service their communities with drinking water, including residences and businesses, such as local airports.

Each of Delta’s almost 850 mainline aircraft may need to be filled multiple times per day depending on how often and where they fly. That can mean completely refilling the tanks multiple times a day.

For example, a flight from Atlanta to Seattle or L.A. would fill up before takeoff and may need to be completely refilled with new water upon arrival on the west coast before returning to Atlanta.

But the airline takes even further measures to make sure the water onboard is clean.

“We adhere to FDA regulations and will not board water onto an aircraft at any domestic or international station where the water quality is known to be out of compliance with government standards,” said Chris Lough, Delta General Manager – Environmental Compliance.

Lough leads the compliance team and helps ensure that water systems are frequently checked on each aircraft.

“In compliance with regulation we disinfect the tank system on every aircraft four times a year, perform water quality sampling once per year, and enter this data into EPA’s Aircraft Reporting and Compliance System,” he said. 

Delta Cabin Maintenance mechanics are responsible for performing the disinfections and sampling. Aircraft water tanks, lines and plumbing fixtures are all included in the disinfection process.

As Lough explained, “Delta disinfects its aircraft through ozonation. Basically, we pump ozone into the tanks, which instantly kills any bacteria, and then we completely flush out the system and refill with clean water. It’s the newer, more efficient industry standard.”

From there, Delta employees on the ground take drinking water service training annually and maintain the water servicing equipment. Taps and surfaces are cleaned between flights.

And what about international stations that do not answer to the EPA?

“If an international station requests approval to board water, it must be able to provide  ongoing analysis of its water quality,” Lough said. “This includes a report from a certified lab that shows the presence or absence of total coliform bacteria, an indicator of potential water contamination.”

Regulatory standards do not allow for the detection of any total coliform bacteria, so Delta only works with stations that can prove there is none to detect.

Currently, Delta has certified and approved approximately 80 international cities for water service.

“Delta’s culture of safety applies to everything we do, and certainly extends to our on-board water system,” Lough said. “Delta vets all domestic and international stations before granting them approval for water servicing and each time a station uploads water to a Delta plane, they have to guarantee compliance with Delta’s water servicing procedures.”

So where does all the used water go?

Well, it depends. Most of the sink water drains lead to an outlet port near the tail of the plane and the water evaporates mid-air if the plane is flying, while for some fleet types a very small amount is captured in separate containers on board.

As for the lavatories, a separate sewage tank captures each flush. Once on the ground, the tank is emptied by a lavatory service truck.