Macerating Toilets vs. Vacuum Marine Toilets Part 2

Macerating Toilets Prevent Odors From Sewage Tank Coming Back Thru Toilet Bowl

All plumbing code for house requires a J trap under the toilet to prevent gases from sewage main to come back thru toilet. Boat building industry has no such requirements.

Vacuum toilets have no water seal. It mostly depends on vacuum (negative pressure) to prevent gases/odors coming back to toilet. In case of vacuum pump being turned off or not working, there is a direct connection between holding tank and toilet without any water seal. There is a valve between hose and toilet bowl and seal on the valve compromised with loss of vacuum.

Macerating toilet, with vented loop has a water seal just like home and seal is reliable even during short term and long term storage.

Low noise

There is a myth that macerating toilets are noisy. Myth has been established by use of rubber impeller in older design macerators. Even macerators to empty out holding tanks and fish boxes use rubber impeller and are noisy.

However almost all manufactures of macerating toilets use centrifugal design for discharge pump. These designs are quieter and make only gurgling sound when runs out of water.

Vacuum toilets are famous for load popping noise. Some customers have described this noise as bullet shooting thru pipe. There are several You Tube videos making fun of vacuum toilet noise on web.

All vacuum toilets and some macerating toilets Marine Toilet require pressurized water for flush water. User should also consider noise generated by diaphragm pump for pressurized water due to toilet system.

Minimum water consumption

It is true that vacuum technique requires less water to evacuate the bowl compared to older style macerator toilets. However water needed to rinse the bowl should also be considered. New control strategies to turn discharge pump and inlet flush water as needed has reduced water consumption in macerating toilets to as low as vacuum toilets.

Minimum power consumption

Power used is measured by amps multiplied by time pump is on.

Vacuum toilet, for example may only draw 6amps. Considering that it runs for 45 seconds, power draw is equal to 6 x 45 =270 amps-sec.

A macerator pump draws 10 amps for 10 seconds. Power draw is 10 x 10 = 100 amps-sec.

Both cases do not consider power required to maintain pressurized water.

Macerator equipped with seawater pump may have a power draw of 18 x 10 = 180 amps-sec, still lower than vacuum toilets.


Vacuum toilet has several components to the system: Toilet, Vacuum generator and holding tank. Components have to be plumbed with leak free joints. There are limitations as to how high vacuum generator can be from the toilet. For boat builders installation requires careful planning. For aftermarket installation a factory certified installer is needed.

Macerator toilets only require installation of one component. Toilet itself is self contained with pumps and control. Only two hoses, discharge and inlet has to be plumbed to toilet. Wiring is also simplified by pre wiring all controls at factory. User only needs to connect to positive and negative at the toilet. Most macerating toilets can be installed by do it yourselfers.


Vacuum toilets function depends on vacuum switch reliability, valve seals, and leaks. Finding a vacuum leak could be a difficult task. Most problems on vacuum system may require a visit from certified technician.

Macerating toilets requires troubleshooting on control. Replacing component of control is easy. Discharge pumps are reliable and seldom needs maintenance.

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