How Do Smart Toilets Work? The Technology Explained
Sensors, pumps, instant water heaters and self-cleaning wands: a plain-English tour of the technology inside an integrated smart toilet.
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A smart toilet works by pairing an ordinary vitreous china bowl with an electronic top unit. That unit holds a water heater, a bidet wand, a seat heater, a fan, sensors and a small control board. It draws water from your supply line and power from a nearby outlet, and it uses sensors and a remote to decide when to open, wash, dry and flush.
Many smart toilets also skip the traditional tank. They flush straight from the supply line, with an electric pump to add force. That one change explains a lot about their plumbing and electrical needs.
This guide walks through each system in turn, using manufacturer documentation from TOTO, Kohler, American Standard and others. It is based on research, not physical testing. If you are new to the category, start with what a smart toilet is.
The two halves: bowl and top unit
Most smart toilets are built in two parts. The bowl is ceramic, like any toilet. The top unit sits on the back of the bowl and contains the electronics, seat and lid. TOTO’s parts listings for the WASHLET G5A, for instance, name a separate bowl and top unit.
This split matters for service. The electronics can usually be removed or replaced without pulling the bowl off the floor.
Sensors: how the toilet knows you’re there
Smart toilets use a few types of sensing:
- Approach sensor. Detects someone walking up so the lid can open. Kohler calls this motion-activated, hands-free opening and closing of the cover on the Veil and Eir.
- Seat sensor. Detects that someone is seated. Wash functions generally won’t run until this is triggered, which helps prevent accidental spraying.
- Foot sensor. Some budget models add a foot-activated sensor. HOROW, for example, lists foot touch as one of four ways to flush and open the lid on its T05.
The control board uses these signals in sequence. Approach opens the lid. Sitting enables washing and seat heat. Standing up and walking away triggers the flush and closes the lid.
Auto flush and the flushing system
Tank vs. tankless
A regular toilet stores water in a tank and releases it by gravity. A smart toilet may do the same, or it may be tankless.
Tankless smart toilets take water straight from the supply line. Because a household line alone may not deliver enough flow for a strong flush, many use an electric pump. Kohler’s spec sheet for the Veil K-5401-PA lists a tankless design with direct water supply and pump-assisted flushing.
Other designs hide a small tank inside the body. HOROW describes its T05 as having a built-in tank and booster pump.
| Tank (gravity or tank-plus-pump) | Tankless (direct supply, often pumped) | |
|---|---|---|
| Where flush water comes from | Stored water | The supply line during the flush |
| Water flow needs | Lower, since the tank refills slowly | Higher; check the minimum flow rate |
| Profile | Taller or bulkier at the back | Lower and more compact |
| Power outage | Depends on model | Needs a backup flush method |
Water pressure and flow
Because tankless toilets depend on the supply line, manufacturers list minimums. Kohler lists a minimum flow rate of 6 gallons per minute for the Veil K-5401-PA and 4 gallons per minute for the Eir. TOTO’s NEOREST NX2 spec sheet lists a minimum of 7.25 psi flowing. If your home has low pressure or a long, narrow supply run, confirm these numbers before buying.
Backup flushing
An electric flush stops working when the power goes out, so manufacturers build in backups. TOTO lists a manual backup flush for power outages on NEOREST models. Kohler says the Veil K-5401-PA supports up to 100 flushes during an outage with a touch button. HOROW notes that the T05’s power-off flush uses a battery pack sold separately.
Dual flush
Most smart toilets offer a full and a reduced flush. TOTO lists 1.0 or 0.8 gallons per flush on the NEOREST NX2, and Kohler lists 0.8 or 1.0 gpf on the Eir. The toilet may choose automatically, or you can pick from the remote.
The automatic lid and seat
A small motor in the top unit lifts and lowers the lid. Some models also raise the seat for standing use. American Standard lists an auto-open and auto-close seat on the Advanced Clean 100 SpaLet. Even when the motor isn’t running, soft-close hinges keep the lid from slamming. Kohler lists Quiet-Close hinges on the Veil, Eir and Innate.
The bidet wand
The wand is the heart of the toilet. It sits retracted behind the bowl and extends when you choose a wash. Inside are one or more spray outlets for rear and front washing.
Typical adjustments include:
- Spray position, moving the wand forward or back
- Pressure, often with several levels
- Water temperature
- Oscillating spray, which moves the wand back and forth
- Pulsating spray, which varies the pressure in a rhythm
- Spray shape, wider or more concentrated
Kohler lists adjustable spray shape, position, pressure, temperature, pulsate and oscillate functions on its stainless steel wands. American Standard uses dual nozzles, one for front and one for rear. For more on what each mode does, see our bidet wash modes guide.
Water heating
The water that reaches the wand is warmed inside the toilet. There are two approaches:
- Instant (tankless) heating. A heater warms water as it flows. TOTO lists an instantaneous water heater for continuous warm water on the NEOREST and G5A lines, and American Standard describes instant heating on the Advanced Clean 100.
- Reservoir heating. A small internal tank keeps water warm. It is simpler, but warm water can run out during a long wash, and keeping the tank warm uses standby power.
Integrated toilets in the mid-range and premium tiers mostly use instant heating. The same split exists in smart toilet seats.
Heated seat, dryer and deodorizer
The heated seat uses a heating element under the seat surface, with adjustable levels. Kohler’s Innate spec sheet mentions an Energy Save feature that tracks usage and adjusts seat heat.
The warm-air dryer is a fan and heater that blows air toward you after washing. Settings range from three to five temperature levels depending on the model. Dryers are gentle, so many people still finish with a little paper.
The deodorizer pulls air from the bowl through a filter, usually carbon, while you are seated. Some models run it automatically.
Self-cleaning systems
Smart toilets use several methods to keep the wand and bowl cleaner between manual cleanings:
- Wand rinse. Water rinses the wand before and after use.
- UV light. Kohler lists UV light cleaning of the wand on the Veil, Eir and Innate.
- Electrolyzed water. TOTO’s EWATER+ uses electrolysis to produce hypochlorous acid, which TOTO says helps keep the wand and bowl sanitary. Kohler lists electrolyzed water wand cleaning on the Veil and Eir.
- Bowl pre-mist. TOTO’s PREMIST and Kohler’s automatic bowl mist wet the bowl before use so waste is less likely to stick.
- Bowl coatings. TOTO describes CEFIONTECT as a very smooth ceramic glaze, and ACTILIGHT as a photocatalytic coating activated by a light in the lid.
None of these replaces regular cleaning. Our self-cleaning bidets explainer goes into more detail.
Controls: remotes, apps and presets
Most smart toilets come with a wireless remote, often wall-mounted. Kohler lists a touch-screen LCD remote on the Veil and Eir, and TOTO lists a remote with memory for four users on the G5A. Kohler’s spec sheet even shows a recommended docking station height on the wall, so the remote is easy to reach while seated.
Some premium models add app control and voice assistants. Check which assistants and phone platforms a model supports before you count on those features.
Power and water connections
Electrical
A smart toilet plugs into a standard 120V outlet, which must be GFCI-protected. TOTO lists a 120V GFCI outlet as required on NEOREST models. Kohler’s spec sheet for the original Veil K-5401 calls for a dedicated 120V, 15A circuit with GFCI protection. American Standard says the seat on its SpaLet bidet toilet draws up to 1300W. Have a licensed electrician add or check the outlet.
Water
The toilet connects to the cold-water shutoff valve with a supply hose. Kohler says to use the hoses supplied with the Veil and not to reuse old ones, and recommends a water hammer arrestor. TOTO’s G5A manual covers cleaning the water supply filter.
Drain
The drain connection is like any floor-mounted toilet, usually at a 12-inch rough-in. Some brands use their own systems. Kohler’s Innate uses a ReadyLock installation system for skirted toilets, and American Standard’s SpaLet toilet uses a drain socket. Our installation guide covers this step by step.
Frequently asked questions
Do smart toilets use more water than regular toilets?
Usually not for flushing. Many smart toilets use 1.0 gallon or less on a full flush, according to TOTO and Kohler spec sheets. The bidet wash adds a little water but can reduce toilet paper use.
Why do some smart toilets have no tank?
A tankless design saves space and gives a lower profile. These toilets flush from the supply line, often using an electric pump, which is why they list minimum flow rates and need backup flushing for outages.
Can a smart toilet seat do everything a smart toilet does?
Most of it. Seats offer washing, a heated seat, a dryer and a deodorizer, and some add an automatic lid. Auto flush and integrated bowl treatments usually need the full toilet. See our best smart toilet seats list.
How much electricity does a smart toilet use?
It depends on the model and settings. Instant water heaters and energy-saving modes reduce standby use. Check the wattage in the spec sheet and use any eco or timer settings the toilet offers.
Bottom line
A smart toilet is a coordinated set of familiar parts: a heater, a pump, a fan, motors and sensors. Knowing how they fit together helps you judge spec sheets and plan the outlet and plumbing. Next, compare smart toilets with regular toilets or read whether smart toilets are worth the money.
