WHAT YOU SHOULD KNOW ABOUT…AIRCRAFT WATER TANKS
The water and waste system supplies potable water to the lavatories and galleys of an airplane, and removes the sink and toilet waste. It is also needed for hot tea and coffee made in the galleys, while regular drinking water is served from bottles. Potable water is stored in a tank capacity of 200 liters in an A320 airplane for example. The airplane has two drain masts. Waste water drains overboard through these two anti-iced drain masts. These wastewater comes from the aircraft galleys and from the lavatories sinks. The forward mast drains wastewater from the forward cabin and the aft drain mast drains wastewater from the aft cabin.
Differential pressure created by the vacuum generator discharges the waste water from the toilet bowl to a waste storage tank in flight, and gravity does so on the ground. Differential pressure created by a vacuum generator forces the waste from toilet bowls into the waste storage tank of the aircraft.
The waste system uses clear water from the potable water system to flush the toilets. The waste tank in an A320 airplane has a usable capacity of 170 liters. A water heater is installed under the washbasin in each toilet unit to supply hot water to the water tap.
The waste water is discarded outside through the drain valve and the heated drain mast. Air stop valves avoid constant aircraft cabin depressurization by opening only when a certain amount of water is collected.
How is the water filled in the aircraft?
Getting water on board is just one of the many processes that take place before takeoff. Before each departure, the service personnel has to make sure that the plane has enough water to service its next trip. If it doesn’t, it’s time to fill up the tank.
Each of Delta’s almost 850 mainline aircraft for example may need to be filled multiple times per day depending on how often and where it flies. That can mean completely refilling the tanks multiple times a day.
Water Servicing Carts are used to fill the water in the airplane. The water servicing panel in an airplane contains a fitting for the attachment of a fill hose. Once the hose is attached, a fill valve is positioned to allow the water to flow into the tank. The quantity indicator on the panel is used to fill the tank. An overfill drain line is plumbed from the top of the tank to the aircraft exterior. When the water reaches the level of the overfill fitting it spills into the overfill line and is drained overboard. Often, tanks are filled until water comes out of the overflow.
The 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. Every airport where water has to be refilled must be able to provide ongoing analysis of its water quality. This includes a report from a certified lab that shows the presence or absence of total coliform bacteria, an indicator of potential water contamination.
Who drains the waste water?
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.
A lavatory Service Cart is used to drain the waste from the aircraft waste tank. The aircraft waste tank is drained by pulling the waste drain valve handle on the toilet servicing panel after attaching the ground lavatory service cart to the 4 inch drain outlet and removing the drain plug. The tank is cleaned by attaching water pressure to the ground flush connection.
Interested in our waste water equipment? Get in touch with your local Area Sales Manager