INTRODUCTION
In the aircraft industry, several systems are designed to provide safety and comfort for the crew and passengers.
Regarding comfort, the water and waste system is designed to provide water for galleys and lavatories. Fresh water is stored and distributed while a different system deals with wastewater. That system includes a thoughtful engineering method to dispose of the different wastes that could occur during the flight.
OVERVIEW
Water must be supplied to different parts of the plane during flight. This water is kept in a tank in the compartment aft of the bulk cargo compartment. The whole system is made up of a passenger water system that stores, delivers, monitors and controls drinkable (potable) water for the galley units and lavatory sink basins.
In this blog, we are going to focus more specifically on the 737-classic model from Boeing.

The 3 main achievements of the water and waste system are the following:
- Filling the water tank on land
- Providing water during the flight
- Storing toilet waste
The water and waste system is made up of:
- Potable water system aims to deliver fresh water to every needed part in the plane (including every component between the water tank and sinks)
- Water tank pressurization system focuses on the pressurization of the water tank and air dealing with the tank (including air compressor, pressure regulator filter, pressure relief valve)
- Wastewater system focuses on water related to lavatory and sinks / galleys wastewater (including drain masts)
- Toilet system includes components related to flushing and toilet water (including waste tank)
The water tank has a capacity of 34 gallons (about 0.15 m3). The water system in the plane needs to be pressurized for altitude just like the cabin, so it gets pressurized by an air inlet (linked to the pneumatic system). Therefore, the water quantity should not exceed 30 gallons (about 0.13 m3). Read More