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Water & Waste System In Aircraft

water system

The quality of the water on an airplane is probably not something you’ve ever thought much about. There are numerous systems are created for the aircraft industry to ensure the crew and passengers’ safety and comfort.

Regarding comfort, the water and waste system is designed to provide water for galleys and lavatories. Fresh water is stored and distributed, while wastewater is dealt with by a separate system.

The system uses a careful engineering process to get rid of the various wastes that might accumulate during the flight.

What to Drink on a Flight?

The air inside an airplane cabin is extremely dry, which increases your chances of dehydration. This may result in unpleasant side effects like headaches, nausea, and other discomforts. Medical professionals advise drinking about a cup of water every hour while flying.

What to Avoid Drinking?

We’re not talking about cups of tap water here. Even though it is allegedly required by U.S. federal law that airlines provide passengers with safe drinking water.

A 2019 scientific study found that due to the frequency with which airline water is found to contain harmful bacteria and the infrequency that aircraft water tanks are cleaned, passengers should avoid drinking tap water on airplanes.

Generally, it’s advised against drinking coffee and tea on flights because most cabin crews brew those beverages on board with tap water.

What to Drink Instead?

Scientists and safety experts advise drinking room-temperature bottled water rather than from the open pitcher on the beverage cart or with ice.

The safety of the water at the airport does not guarantee that it will remain safe during the transfer to the aircraft and the subsequent storage operations.

Understanding the aircraft drinking-water supply and transfer chain will help to highlight the points at which water can become contaminated en route to the aircraft’s tap.

Aircraft drinking-water chain

There are four main parts that make up the aircraft drinking-water supply and transfer chain:

  1. The source of water coming into the airport, The airport water system includes the on-site distribution system. And might also include treatment facilities, if the airport generates its own potable water. In the event that the airport generates its own potable water, it might also include treatment facilities.
  2. The water delivery and transfer system is also known as the transfer point or “watering point.” A temporary connection is typically made using potable water vehicles and carts, refilled containers, or hoses between the airport’s hard-plumbed distribution system and the aircraft water system (for example, at a hydrant).
  3. Multiple opportunities exist for contaminants to enter the drinking water during this water transfer process.
  4. The aircraft water system, which includes the water service panel, the filler neck of the aircraft’s finished potable water tank, and all finished water storage tanks, including refillable containers/urns, piping, treatment equipment, and plumbing fixtures within the aircraft that supply water to passengers or crew.

How is the water in the airplane filled?

Getting water on board is just one of many processes that occur prior to takeoff. The service personnel must ensure that the plane has enough water for the next trip before each departure. If not, it’s time to refill the tank.

Water Servicing Carts are used to fill the airplane’s water tanks. An airplane’s water servicing panel includes a fitting for attaching a fill hose. Once the hose is connected, a fill valve is installed to allow water to enter the tank.

To fill the tank, use the quantity indicator on the panel. An overfill drain line runs from the tank’s top to the aircraft’s exterior.

When the water reaches the overfill fitting’s level, it spills into the overfill line and drains overboard. Tanks are frequently filled to the point of overflowing with water.

Waste water drain system?

While some fleet types have minimal amounts of sink water captured in separate onboard containers, the majority of sink water drains lead to an outlet port close to the plane’s tail and the water evaporates mid-air if the plane is in flight.

The waste from the aircraft waste tank is drained using a lavatory Service Cart. After connecting the ground lavatory service cart to the 4-inch drain outlet and removing the drain plug, the aircraft waste tank is drained by pulling the waste drain valve handle on the toilet servicing panel.

The tank can be cleaned by applying water pressure to the ground flush connection.


The Vacuum Toilet Assembly is a complete, self-contained, freestanding unit ready to be bolted to the floor of the lavatory housing. It is the interface for the user and receives the waste matter.

On request, the toilet assembly carries out a flush sequence opening a path to enable the cabin-to-waste tank differential pressure to transport the waste matter via the tubing system to the Waste Tanks.

The toilet assembly rinses itself by utilizing clear water (in most cases for weight-saving purposes only 0,1 liters per flush), obtained from the pressurized potable water system.


The Waste Tank Module stores the waste received from the tubing during the entire flight for discharge on the ground. It is equipped with level measurement.

A key design task is to separate the high-speed incoming waste matter in order to avoid impacting the tank structure and to safely avoid waste matter going overboard via the tank ventilation channel.

In normal operation, the tank is loaded by external overpressure and shall hence be stiff enough to avoid collapsing.

For a weight-optimized design, this is in most cases achieved by a proper carbon fiber composite design.


Generators are electric motor-powered single-stage centrifugal compressors utilized to generate the required differential pressure for the waste system while the aircraft is flying at low altitudes or being on the ground.

Hence, these generators are optimized for non-continuous operation and very fast acceleration of the rotational speed. The electronic controller enables the utilization of AC/DC networks with variable frequency.

A specific software minimizes the noise levels in the different working regimes, optimizes the throughput performance, and minimizes the electric power demand in operation. A CAN-bus interface allows for data communication with the aircraft’s onboard network.

Bottom-line advice. To be extra safe:

  • NEVER drink any water onboard that isn’t in a sealed bottle.
  • Do not drink coffee or tea onboard.
  • Do not wash your hands in the bathroom; bring hand sanitizer with you instead.