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Waste water tank contents

Aviation Mechanic Airframe (AMA) practice question 1 of 2 on Water and Waste Systems. ACS element AM.II.O.K1 · difficulty: recall. Want to answer it in a timed quiz? Use the Aviation Mechanic Airframe (AMA) practice mode.

Question bank updated 2026-09-22

QUESTIONOn a transport category airplane, what do the waste water tanks collect?

  1. AGray water from the galleys and lavatories
  2. BCondensed water removed by the air conditioning packs
  3. CRinse water returned from the potable water tanks
Show the answer and explanation

Correct answer: A. Gray water from the galleys and lavatories

  • A — correct The handbook states that the waste water tanks collect the gray water coming from the galleys and the lavatories.
  • B — incorrect Moisture taken out of conditioned air is handled by the water separator in the air conditioning pack, not routed into the waste water tanks.
  • C — incorrect The potable tanks supply water outward to the lavatories and galleys through the water lines; nothing is returned from them to the waste tanks.

BACKGROUND

Transport category airplanes carry two related but separate plumbing systems. Potable water lines carry water from the potable tanks to the lavatories and galleys for drinking and hand washing. The used water that drains from those sinks is called gray water, and it is collected by the waste water tanks. Because both the supply lines and the waste drains run through cold areas of the airplane, they are listed among the components that must be protected from ice formation.

STUDY TIP

Fix the direction of flow in your mind: potable tanks feed the lavatories and galleys, and the waste water tanks receive the gray water that drains back out of them.

KEY POINTS

  • Potable water lines carry water from the potable tanks to the lavatories and galleys.
  • Waste water tanks collect the gray water from the galleys and lavatories.
  • Water and waste lines and drains are on the list of aircraft components protected from ice.

SOURCES

  • FAA-H-8083-31B ch15 "Water & Waste Tank Ice Prevention" (sources/ama-airframe/ch15.txt)
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MORE ON WATER AND WASTE SYSTEMS

SkyDrill is not affiliated with the FAA. This is an original practice item based on FAA-H-8083-31B Aviation Maintenance Technician Handbook – Airframe, and 14 CFR part 43. Regulations and handbooks are revised; confirm details against the current edition.