March 17, 2008

Reservoir-less Toilets
Miami Beach, United States

Reservoir-less toilet in my Miami Beach hotel bathroom

I've come across a handful of western toilets throughout SE Asia and Latin America that don't have water reservoirs (tanks) attached to them. Instead, these units tap directly into the water pipes running throughout the building.

The benefit of this design is immediately obvious: Fewer moving parts to break down (such as leaking gaskets), strong flushes that last as long as you hold the handle down, and no waiting period for a second flush.

Toilet reservoir components

I don't understand why we're still buying and building toilets that use an antiquated/complex water reservoir design. The functionality can be dressed up for the home, but this is the way all western toilets should be installed, not just those limited to public restrooms.

When's the last time you saw a toilet with a reservoir in an airport? The (aesthetically lackluster) unit in this hotel room even has a handle that briefly simulates the functionality of a reservoir by flushing for two or three seconds after a quick pull. Reservoir-less toilets are cheaper, faster, more reliable, and probably waste less water. So, what gives?


The United States

Craig |

March 20th, 2008

Dad e-mailed me about this, noting that sufficient water pressure in residential homes is an issue:

Reservoirs on toilets are used to provide enough pressure and volume to flush poop down the toilet, as household plumbing typically cannot provide that. That's why older flush toilets had reservoirs up at or above head height - more potential energy means more kinetic energy on release.

Building a new home, I'd trade water reservoirs for some type of booster pump.

The United States


November 10th, 2010

A poop booster pump. Nice.

A water pump with a VFD is not going to simplify the process… and VFDs are expensive. The system would take a pump, motor (maybe a VFD rated), a pressure sensor to provide feedback to the VFD, and whatever other piping/resevoirs are need. Not to mention how many components there are in a VFD.

And just think of what would happen if a pipe burst in your house… full fire-hose quality water pressure over normal flow.

If you're building a new home, make sure your pipes are big enough to reduce as much pressure dop as you can, and don't build on top of a hill.

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