A tankless toilet has no porcelain water-storage tank. Water flows directly from your house supply line to the bowl during flush, controlled by an integrated electronic valve. The result: a lower, sleeker silhouette (no tank to add height behind the bowl), instant flush availability (no waiting for tank refill), and a more modern visual presence.

How a tankless toilet works without a tank

The traditional toilet flushes by releasing the water stored in the tank into the bowl via gravity. A tankless toilet replaces this with an electronic flush mechanism that opens a valve on the supply line, allowing water to flow through pressurized pipes into the bowl. Most tankless models also include an integrated booster pump (a small electric pump that boosts pressure for adequate flush velocity), since US household water pressure (typically 50–80 PSI) isn't always enough for unassisted gravity-free flushing.

The requirement: stable water supply pressure

Tankless toilets need stable water-supply pressure of at least 25 PSI dynamic (during flow) — most US homes have this, but homes at the end of long supply lines, in higher elevations, or with old galvanized piping may not. If your shower's water pressure feels weak, a tankless toilet may not flush reliably.

Tankless availability — primarily premium smart toilets

TOTO Neorest 700H / 750H / NX1 / NX2 ($4,000–$10,000) — the premium tankless integrated combo. Heated seat, bidet wash, dryer, auto open/close lid.
Kohler Numi 2.0 ($6,800) — Kohler's premium tankless smart toilet. Foot-sensor flush, Bluetooth speakers, mood lighting.
Kohler Veil Smart ($3,800–$4,500) — mid-premium tankless with bidet wash and heated seat.
Horow HWMT-8733 ($1,500–$1,800) — value-tier tankless smart toilet. Foot-sensor flush, heated seat, integrated bidet.
Woodbridge F1-0020 ($1,200) — entry-tier tankless smart toilet at the budget end.
Geberit AquaClean Tuma ($3,200) — European tankless smart-toilet wall-hung.

The install requirements

Stable supply pressure: 25+ PSI dynamic. Test your bathroom's pressure before purchase.
GFCI electrical outlet within 3 feet: required for the electronic flush valve and integrated features (heated seat, bidet, dryer).
Dedicated cold-water supply line: the 3/8" supply line that feeds a traditional toilet works, but should be in good condition (replace if it's a 20+ year old line).
Tankless toilets are heavier than two-piece equivalents — the one-piece engineering puts the weight in the bowl/base. Two-person install often needed.

The pros and cons (vs traditional tank toilets)

Pros:

Lower, sleeker silhouette (typically 20–24" total height vs 28–32" for two-piece)
Instant flush availability (no waiting for tank refill)
More water-efficient — uses only what's needed per flush, no excess tank water
Easier to clean (no tank seam, no flapper hardware)

Cons:

Premium pricing ($1,500–$10,000)
Requires electrical service (GFCI outlet)
Requires adequate water-supply pressure
When the electronic flush valve fails (eventually), repair is more complex and expensive than a $5 flapper replacement
Power outage = no flush (some models have battery backup; most don't)

Where tankless is the right choice

Master bath in an owner-occupied home where premium design matters
Low-profile bathroom designs (low-ceiling bathrooms, under-window installations)
Bathrooms already getting electrical service for smart features
Modern designer bathrooms where the toilet silhouette is part of the visual statement