How to install a Japanese toilet seat

20 June 2026 — Mizu Bidet

Installing a Japanese toilet seat does not require a plumber or specific tools. Allow 10 to 20 minutes for an electric model with a hot water connection. The entire installation is reversible.

⏱ 10 – 20 minutes Adjustable wrench + screwdriver Electrical outlet required Reversible installation

Toilet compatibility

✓D-shape (elongated) or O-shape (oval) — most common in France

✓Fixing hole spacing between 14 and 20 cm

✓At least 10 cm free space between the wall and the back edge of the bowl

✓Water inlet thread 3/8” or 1/2” (connector included in the kit)

✓Dedicated grounded electrical outlet within 1.20 m of the toilet

⚠Wall-hung toilet with concealed cistern — contact us to check feasibility

What you need

Tools

Adjustable wrench (size 13)
Phillips screwdriver
Spirit level (optional)
Cloth or towel

Provided in the Mizu kit

Toilet seat with mounting plate
3/8” metal T-connector
Braided metal hose
Teflon tape
Spare seals
Illustrated instructions

Before you start: turn off the stopcock (behind or under the cistern), flush the toilet, then place a cloth under the connections to absorb any residual drips.

4-step installation

Remove the old seat and fix the plate

Unscrew the two side fasteners of the old seat (accessible from below with a screwdriver)
Lift and remove the old seat
Thoroughly clean the area around the fixing holes and dry
Place the Mizu mounting plate over the existing holes and align it
Insert the provided anchors and screw in the bolts with a screwdriver, without forcing
Check for horizontal level with a spirit level — the plate must be perfectly level

Stability: the plate must be firm, with no lateral play. If it moves, tighten by an additional quarter turn.

Clip the toilet seat onto the plate

Slide the Mizu toilet seat into the plate's runners until you hear the locking click
Press lightly forwards, backwards, and sideways to confirm stability
Test the release button — the toilet seat should be easily removable for cleaning

The toilet seat is correctly installed when the gap between the seat and the bowl is uniform all around.

Connect the water supply

The T-connector is placed between the stopcock and the existing cistern hose. It creates a second outlet dedicated to the toilet seat.

Wrap 3 to 4 turns of Teflon tape clockwise around the stopcock thread
Screw the T-connector onto the stopcock by hand, then gently tighten with the wrench — half a turn is sufficient
Reconnect the cistern hose to the upper outlet of the T-connector
Connect the provided braided hose to the side outlet of the T-connector, then to the water inlet of the toilet seat
Never overtighten — the rubber seals ensure watertightness

Mizu Pro (hot water): install a second T-connector on the hot water supply under the washbasin. Connected by the second hose, it supplies hot water to the toilet seat nozzle.

Electrical connection and commissioning

Plug the cord into a dedicated, grounded outlet, within 1.20 m of the toilet, compliant with NF C 15-100
Do not use a multi-socket adapter — the toilet seat must have its own outlet
Gradually reopen the stopcock and inspect all connections — no drips should appear
Watertightness confirmed: power on the toilet seat
Test each function from the remote control: rear spray, front spray, drying, seat heating
Adjust the spray temperature between 35 and 40°C for optimal comfort

Safety: If you do not have a grounded outlet nearby, have an electrician install one before installation. Never plug the toilet seat into an ungrounded outlet.

Frequently Asked Questions

Do I need a plumber or an electrician?

No, if you already have a grounded outlet near the toilet. The hydraulic connection does not require any particular skill — only an adjustable wrench and a screwdriver. If no suitable outlet is available, call an electrician to install one.

Is my toilet compatible?

Mizu toilet seats are compatible with the vast majority of toilets with exposed cisterns. Key points: hole spacing between 14 and 20 cm, at least 10 cm of space between the wall and the bowl, grounded outlet within 1.20 m. If in doubt, send us a photo and we will check.

I have a leak after installation, what should I do?

Immediately turn off the water. Dry and locate the source. Disassemble the affected connection, check that the seal is centered, and retighten. If the leak persists, wrap 3 to 4 turns of Teflon tape around the thread before re-screwing.

Can I easily remove the toilet seat for cleaning?

Yes — all Mizu toilet seats are equipped with a quick-clip system. A button on the plate allows the toilet seat to be detached in one second to clean the entire bowl. Re-installation is instant.

Will the plate leave marks if I uninstall it?

No. The plate attaches to the same holes as your old toilet seat — no additional drilling, no permanent marks. Disassembly takes less than 5 minutes.

Questions about your toilet's compatibility? Send us a photo, and we'll check within 24 hours.

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