Why are tankless toilets mainly in commercial buildings?

Most toilets in house have tanks. You press the lever, the tank empties, flushing the toilet, the tank refills for next time. Many commercial buildings have toilets without tanks, just a bowl mounted on the wall. (Side bonus, it’s a whole lot easier to clean the floor when the bowl is mounted on the wall.)

Why don’t homes have tankless toilets? I seem to have to replace the flapper/float assemblies in toilets every few years. Something starts sticking and my toilets run otherwise. If I could dispense with the tanks this wouldn’t be a problem.

In areas with low water pressure, I know the tank provides the volume/pressure to force everything down the drain, but my water pressure is fine. Our house has a regulator to decrease the pressure before it enters the pipes.

It’s 3:00 AM, and your mate silently slips out of bed to go to the bathroom.


Now, the whole house is awake.

That’s about the biggest reason they’ve not caught on for residential use. Also, home water pressure is usually too low for a direct flush.

My grandparent’s high-rise apartment in NY had a tankless toilet. It used to scared the carp out of me as a little kid. So, it’s doubly effective.

In addition to what has been said, initial cost is much higher.

I always assumed that they did have tanks, just hidden behind wall panels.

Just be thankful you’re not in Brazil; the tanks are on the roof there!

Just had to say I love this image!

You can test this by flushing the toilet, and then flushing it again a few seconds later. If there is a tank, then it will take a minute or two before you can flush it again with the same effect. I think.

It’s not the water pressure that is the issue, it is the available volume. The tank on a commode supplies perhaps 2psi, while there is usually over 50psi available from the system.

Residential connections usually use either a 3/4" pipe, and/or an equivalent orifice restrictor or restrictive meter. Commercial connections to the main use whatever is speced, and are charged higher rates according to a schedule based on the size of their connection. The size of this restriction limits the rate (gpm) at which water can be supplied. Because most commercial buildings are required to have a fire sprinkler system, they are assured of having a large enough connection to operate a Sloan valve (tank-less) toilet.

Having such restrictions makes sure that when everyone is watering their lawn, everyone gets at least some water. If everyone had a 2" connection, then the customers nearest the header tanks would get it all.

Such issues are part of the reason for zoning regulations. Commercial areas usually have larger water mains, 3 phase power lines, and wider alleys for fire trucks.

Having the tank hidden “in the wall” is not uncommon in Norway in newer residential bathrooms, but much more common in commercial bathrooms. It’s more expensive to install, and usually more difficult to repair, but for commercial bathrooms it probably makes economic sense since they make it so much easier to clean the facilities.

I there are actual tankless toilets I expect the sanitation issue is important in making that choice as well.

Thanks Kevbo. That makes sense. It’s not the water pressure, it’s the through put. Too bad. I would be willing to pay extra for a toilet that never runs on, and was easy to clean under. Oh well.

Yeah, but it also increases the chances that it will become loose (or even break off) from the wall.

Even a small vertical support would do a lot for taking strain off the connections. I’m somewhat overweight, and some of those toilets really scare me.

 If you're willing to spend the money I'm reasonably sure you could obtain  a pressure assisted wall mount throne.

So how would you jiggle the handle?

Of course that first guy would be able to water the whole block with his sprinkler. Hurray for 35m tall water sprinkler. At least until it explodes, maiming several small children and their beloved pets in a scandal known as waterga . . . :confused:

My first couple of apartments had tankless toilets - one was in a 12 story building, the other in a 3 story building, if that makes any difference.

One night the valve malfunctioned - that was memorable. Sort of a cross between a howling banshee and the Loch Ness monster choking on its own phlegm. Fortunately, I knew where the water shut-off valve was.

Kevbo has it. A commercial toilet uses (IIRC) a 1 1/2" Supply, so a house with a 3/4 supply (for the whole house) would not even have close to the volume needed.

Basically a toilet needs 1-2 gallons of water delivered in a few seconds to flush. This would be equal to a flow rate of around 40 gallons per minute, way more than a typical home water supply can provide without a storage tank.

I do remember seeing a toilet for home use that had a pressurized tank that refilled/pressurized from the home water supply to give some of the benefits of a commercial toilet but I do not know if it is still made.

I did find this site that has some interesing info.

Pressure assist toilets are still very common, especially because all toilets sold in the USA are low volume units.

They’re usually pushbutton, or the handle protrudes through the wall panel.

I’ve seen toilets like that for installation in a basement without breaking concrete (it flushes “uphill”). Saniflo makes a few. And here is a general discussion of upflushing basement toilets.