TOTO WASHLET C5 vs S2 vs S5: What Changed From the C2, C5 and K300, and Should You Upgrade?

If you're shopping for a TOTO WASHLET, you'll see two generations on sale side by side: the C5 (and the older C2), and the newer S2 and S5. The names don't make the difference obvious, and the C5 is still sold by Amazon itself. This guide explains what TOTO actually changed, using TOTO's own spec sheets and manuals, which one to buy now, and whether it's worth replacing an older WASHLET that still works.

What changed: tank heating became instant

The C2 and C5 keep warm water in a small built-in tank. TOTO's manuals list it at about 0.13 gallons, warmed by a 225 W heater (C5 manual). That is enough for a normal wash, but a long wash, or two people in a row, can run it down until it reheats. The current S2 and S5 use an instantaneous water heater, which TOTO describes as giving continuous warm water. That is the change you'll feel most.

The second change is cleaning. The C2 and C5 already had PREMIST (a mist that wets the bowl before use) and EWATER+, but on these models EWATER+ cleans the wand. TOTO's current comparison table lists EWATER+ on the S2 and S5 for both the bowl and the wand (TOTO USA). The older K300 already had instant heating and a slim wireless remote; its R version added EWATER+ for the wand.

C5 vs S2 vs S5, side by side

All three heat the seat, wash front and rear with warm water, dry you with warm air and filter odors. So the decision comes down to two things: instant or tank warm water, and remote or side panel. One practical note: instant heating draws much more power while it runs. TOTO's spec sheets list about 1,290 W for an S-series seat with instant heating versus 403 W typical for the tank-heated C2, so plug it into an outlet that matches the manual's requirements, and TOTO recommends a GFCI outlet in bathrooms.

Which one to buy now

The drawings below are simple illustrations, not product photos. Prices and stock on Amazon change often, so compare current prices: the C5 is the better buy only if it costs meaningfully less.

TOTO WASHLET S2: the one most people should buy. Instant warm water, a dryer, a deodorizer, PREMIST and EWATER+ for the bowl and the wand, controlled from a panel on the side of the seat. It fixes the one real weakness of the C2 and C5.

TOTO WASHLET S5: the S2 with a remote. The same instant heating and cleaning features, with a wireless remote you can mount on the wall, so the seat itself looks cleaner. The natural upgrade for anyone used to the C5's remote.

TOTO WASHLET C5: still a capable seat. It has a wireless remote, a dryer, a deodorizer, PREMIST and EWATER+ for the wand. Its only real drawback is the small warm-water tank. For one person who washes quickly, it is perfectly good, especially if you find it for noticeably less than the S5.

Already have a C2, C5 or K300? Should you upgrade?

• Keep it if it works and the warm water lasts long enough for you. The core features (warm wash, heated seat, dryer, deodorizer) are the same.
• Upgrade to an S2 or S5 if the water turns cool during long washes, or if two people use the toilet back to back. That is the tank's limit, and instant heating removes it.
• Upgrade if you want EWATER+ to clean the bowl too, not just the wand.
• A K300 already has instant heating, so the main gain from an S5 is the newer cleaning features.

Installing the new seat follows the same steps as any bidet seat: shut off the water, swap the mounting plate, connect the supply hose through the T-valve and plug in. Follow the new seat's manual. See the step-by-step guide in TOTO WASHLET vs Brondell vs Bio Bidet, and our full TOTO WASHLET guide for the rest of the lineup.

Which one suits you?

• Most people: WASHLET S2.
• You want a remote: WASHLET S5.
• One user, quick washes, and the C5 is noticeably cheaper: WASHLET C5.
• You own a C2 or C5 and the warm water runs out: upgrade to an S2 or S5.