Water and Waste Systems

Gulfstream GVII

Eddie sez:

For a quick refresher or a good intro, be sure to see Ivan Luciani's notes: Water and Waste Systems.

Everything here is from the references shown below, with a few comments in an alternate color.

[PAS, p. 16-1]

  • The Potable Water System (PWS) supplies filtered water to the galley sinks and coffee maker, the lavatories, sinks, and toilets.

  • Storage: two 15 gallon tanks located in baggage compartment that can be serviced by a water panel below the external baggage door or manually from the top of each tank with a funnel.

  • A Vacuum Waste System (VWS) transports waste from two vacuum toilets to a waste storage tank using differential pressure between cabin and waste tank or from a suction vacuum generator.

  • Single point failure of systems negated by design through enhanced redundancy.

  • Control is through the Gulfstream Cabin Management System (GCMS) at the vestibule and galley.

Last revision:




Photo: Water system drains, PAS, 16-3
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[PAS, p. 16-3]

  • There are two drains on the bottom of the aircraft.

  • A heated drain mast is located aft where water drains out during flight assisted by the aircraft's nose up attitude and differential pressure.

  • A penetration port is located forward where water drains after landing assisted by the aircraft's nose down attitude. Forward drain valves from potable water (2), gray water (1) are open only open in WOW ground mode.

External Water Fill


Photo: External water system fill, PAS, 16-21
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[PAS, p. 16-21]

  • External fill is accomplished from External Service Panel (ESP). Follow instruction label inside ESP.

  • Turn on Ground Service Bus (GSB) switch if no AC power.

  • Water system turned off when ESP door is opened, shuts off air compressor if operating, shuts off sterilizers, closes tank isolation valves, powers water level indicator, and performs indicator BIT.

  • Turn and pull control handle for Tank A or B, opens tank fill valve, relieves residual pressure in that system.

  • Remove external fill cap from applicable fill port.

  • Connect service hose to fill port, max design fill pressure is 55 psi, fill until water overflows from drain mast. You can also fill to level desired via indicator.

  • Remove service hose from fill port, allow excess water to drain from fill port then, push and turn control handle to close fill valve, secure fill cap.

  • Can fill tanks without power, but the water level indicator and fill port heaters are not available with GSB unpowered.

Freeze Protection


Photo: Water system control panel, PAS, 16-4
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[PAS, p. 16-4]

  • Freeze protection is provided for components that get wet / prone to freezing via insulation and auto electric heat when power is applied to aircraft. The heaters require AC power except there are external water fill heaters which use DC power from GSB.

  • Tanks, supply lines, and drain lines are protected by heating pads, heated flex hose, innerline™ heaters, and cabin conditioned air.

  • The drain mast is heated when GALLEY and CABIN PWR ON via TSCs 2-5.

  • Forward Penetration Port is heated anytime the gear is down.

  • Three water heaters for sink hot water for the galley and each lavatory.

[PAS, p. 16-6] Waste system freeze protection uses AC powered auto heat via waste blanket heaters, waste tube heaters, vacuum tube heaters, and fitting heaters.

Internal Water Fill


Photo: Internal water system fill, PAS, 16-22
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[PAS, p. 16-]

  • Accomplished at water tanks in baggage compartment behind right side wall.

  • First press the Internal Fill Mode button above water tanks; Turns off water system, turns off air compressor if operating, turns off sterilizers, closes tank isolation valves, powers water level indicator, performs indicator BIT.

  • Lift lever on manual pressure relief valve on each tank, relieves residual pressure.

  • Remove manual fill cap(s) at top of tank.

  • Fill tank(s): will need funnel or Gulfstream hose adapter.

  • Replace manual fill cap(s).

  • Lower levers on manual pressure relief valves.

  • Press Internal Fill Mode button again, turns water level indicator OFF.

  • Turn water system ON via GCMS touchscreen.

This is how we fill our system since we never use FBO water, only spring water from bottles. We've found that on the road we can get a way with only filling one tank and that the tank on the left is easier since the funnel fits in straight and there is less chance of spilling water from our one gallon jugs. But if you do this, you will have to remember to direct all systems to Tank A.

Waste System


Photo: Toilet system, PAS, 16-5
Click photo for a larger image

[PAS, p. 16-5]

  • There are two toilets with toilet bowls made of slippery homogeneous material. The water system must be ON via GCMS for bowl rinse feature.

  • Each toilet controlled by Flush Control Unit (FCU) and a switch on decorative paneling to flush. One water droplet for less rinse, 2 water droplets for more rinse, 3 upward arrows for vent.

  • Vacuum for flush comes from two sources: cabin differential pressure or a vacuum generator. The vacuum generator is needed when < 6 psid (aircraft < 16,000’), AC power required, so you need APU or Ext AC to flush toilet during ground ops. Both toilets can flush simultaneously regardless of source.

  • A manual flush valve is operable > 16,000’ if normal system fails (e.g. flush switch failure). Opened manually by manual flush handle, no rinse water is used.

  • Storage Tank: 11.5 Gal usable capacity. When tank indicates full, FCU limits to 8 additional normal flushes. Can use manual flush until no air left in storage tank.


Photo: Vacuum waste service panel, PAS, 16-7
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[PAS, p. 16-7]

  • A Vacuum Waste Service Panel located on the right side of aircraft aft of right wing trailing edge.

  • Contains 2 servicing fixtures: waste drain valve and rinse drain nipple.

  • When the service panel door is open on the ground, the vacuum generator is shut off and prevents toilets from flushing.

  • Waste drain valve has a 2-stage interlocking security system. The first stage is the internal door. The second stage is an outer cap.

  • A rinse drain nipple is connected for water to rinse waste tank. Rinse tank approx 2 to 3 minutes.


Photo: Water and waste service doors, PAS, 16-11
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[PAS, p. 16-11]

Water Storage Tanks


Photo: Water system tanks, PAS, 16-2
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[PAS, p. 16-2]

  • There are two water tanks, called A and B, located inside the baggage compartment right side wall, each with a 15 gallon capacity pressurized by an onboard air compressor which activates when tank pressure ≤ 42 psi. The compressor turns OFF when tank pressure = 48 psi. Bleed Air is used as a secondary source.

  • Dual supply lines provide redundancy from each tank to all fixtures. Water departs tanks and passes through a filter and an ultraviolet light sterilization for purification.

See Also:

Gulfstream GVII-G500 Production Aircraft Systems, Revision 3, July 15, 2019