15-Second Answer
Japanese toilets usually have two flush options: 大 (dai, large flush) and 小 (sho, small flush). 大 is the standard choice — use it when in doubt. Many toilets also have a simple lever instead. The tricky part is finding the button among the many on a washlet panel, but flush buttons are almost always labelled 大 / 小 or marked separately from the other controls.
Why Are There Two Flush Options?
Japanese toilets are designed with water efficiency in mind. The large flush (大) uses a full volume of water for a thorough rinse. The small flush (小) uses less water and is intended for lighter use. The distinction helps reduce water consumption over time.
If you are unsure which to use, 大 is always fine. That is the standard flush.
Where Is the Flush Button?
Location varies by toilet type. The most common places to look:
- Lever on the tank — common on older or simpler toilets; usually on the top or side of the water tank behind the bowl
- Button on the side of the tank — found on many business hotel toilets
- Wall-mounted remote panel — typical on washlet-equipped toilets; the flush buttons are usually at the top or bottom of the panel, separated from the bidet controls
- Panel on the side of the seat unit — on integrated toilet and washlet units
In all cases, look for 大 / 小 labelling, or the word "flush" on English-labelled panels.
What About All the Other Buttons?
Washlet remotes can look overwhelming at first — bidet, rear wash, dryer, seat temperature, sound masking, and more. The important thing to know: buttons you do not press do nothing. There is no risk of accidentally triggering something by simply looking at the panel.
Take a moment, find the 大 / 小 buttons, and ignore the rest. The flush controls are almost always visually grouped or physically separate from the hygiene controls.
On some panels, the flush button is on the wall unit but the bidet controls are on an arm attached to the seat. If you see two separate panels, the wall one typically handles flushing and the seat-arm one handles the wash functions.
What If You Still Can't Find It?
Work through these in order:
- Check the top and sides of the water tank behind the bowl
- Check the wall panel — flush buttons are usually at the top or edge
- Check the side panel on the seat unit
- Look for a physical lever on the tank — push it forward or lift it
One of those four will have what you need.
What Japanese People Actually Do
Most people use 大 and 小 according to the situation. When in a hurry or unsure, 大 is the default — nobody thinks twice about it.
Bottom Line
Look for 大 / 小 — that is the flush. If you cannot find it immediately, check the tank, the wall panel, and the seat-side panel in that order. When in doubt, press 大. It works every time.
