Not all do, Roger...
Electric toilets designed to use pressurized water are VERY quiet and use less than half the flush water required by raw water toilets. Most are available as either conversion kits or complete toilets. For quality and durability, I recommend the Raritan SeaEra. I would stay away from the Jabsco 29200 conversion...if for no other reason than it uses twice the power needed by pressurized flush water toilets and nearly twice as much as other raw water toilets: 25a/flush vs 16 for other raw water toilets and 10 for pressurized flush water versions.
