I installed and tested the TOTO Washlet C5 for my review, and it earned its reputation as a dependable mid-range bidet seat. It had one habit I never got used to, though: the warm water ran out. In my testing, the C5’s water started above 100°F, began cooling at the 30-second mark, and felt cool by 40 seconds.
TOTO has since discontinued the C5 and replaced it with the Washlet S5. For anyone buying new, the S5 is the better pick, because its instantaneous heater delivers continuous warm water, and it adds four user presets, a nightlight, and a round-bowl option the C5 never had. If you already own a working C5, the upgrade only makes sense if that 40-second warm-water window bugs you.
A quick note on how I’m handling the toto c5 vs s5 comparison: everything I say about the C5 comes from my own hands-on testing. I have not tested the S5, so every S5 detail below comes from the spec sheets published by TOTO and Bidet King. I’ll label them that way throughout.
TOTO C5 vs. S5: Quick Summary Table
The S5 keeps most of what I liked about the C5 and fixes its biggest weakness, the tank heater. Here’s the side-by-side, with C5 numbers from my testing and S5 numbers from the spec sheet.
| Feature | TOTO Washlet C5 (my testing) | TOTO Washlet S5 (spec sheet) |
|---|---|---|
| Status | Discontinued | Current model |
| Price | Leftover stock only | About $668 to $780 |
| Heater | Tank (reservoir) | Instantaneous |
| Warm water duration | About 30 to 40 seconds | Continuous |
| Spray volume | About 0.11 gal/min on high | 0.07 to 0.11 gal/min rear, 0.08 to 0.11 front |
| User presets | 2 | 4 |
| Nightlight | No | Yes |
| Sizes | Elongated (SW3084) | Elongated and round |
| EWATER+ | Yes (wand) | Yes (wand) |
| PREMIST | Yes | Yes |
| Warm air dryer | Yes | Yes, 3 settings |
| Warranty | 1 year | 1 year limited |
The rows that differ are the ones you’ll notice daily: heater type, warm water duration, presets, and the nightlight. The spray, dryer, and cleaning features are close to identical on paper.
Why TOTO Replaced the C5
TOTO replaced the C5 because its tank heater had become the weak spot in an otherwise solid seat, and the S5 swaps it for on-demand heating. The replacement also modernized the controls and seat shell while keeping the C5’s familiar feature set.
What Changed in the Replacement?
Going by the S5 spec sheet, the changes fall into a few buckets:
- Heating: An instantaneous water heater replaces the C5’s reservoir tank, so warm water keeps flowing for the full wash.
- Controls: The wireless remote now stores four user presets, up from the C5’s two, and it sits in a docking station.
- Lighting: The S5 adds a nightlight. My C5 had none.
- Seat design: The S5 uses a seamless seat with TOTO’s CLEAN RESIN surface.
- Sizing: The S5 comes in elongated and round. The C5 version I tested (SW3084) was elongated only.
What stayed put: PREMIST, EWATER+ wand cleaning, the heated seat, a warm air dryer, the deodorizer, SoftClose, and a one-year warranty. If you liked how the C5 washed, the S5 is built on the same core recipe.
Can You Still Buy a C5?
Bidet King now lists the C5 as discontinued and points shoppers to the S5. You’ll still spot leftover C5 stock at some retailers, sometimes discounted.
I’d be cautious there. A discontinued seat with a one-year warranty means you’re betting on parts availability down the road. If you find a C5 at a steep discount and you’re fine with short warm-water cycles, it’s still a good seat. I covered its strengths and quirks in my full TOTO C5 Washlet review. At close to S5 pricing, though, I wouldn’t bother.
The Big Change: Tank Heater vs. Instant Heater
The heater swap is the single biggest difference between these two seats. The C5 uses a reservoir-style heater that stores a small amount of pre-warmed water, while the S5 uses an instantaneous water heater that warms water as it flows.
When Did My C5’s Water Turn Cool?
In my testing, the C5’s warm water tank held roughly 30 to 40 seconds of heated cleansing. Here’s how it played out:
- 0 seconds: Water came out at 100°F or a bit above. Comfortable right away.
- 30 seconds: I could feel it start to cool.
- 40 seconds: It ran cool.
For a quick rear wash, 30 seconds is enough. For a front wash followed by a rear wash, or for anyone who likes a slow, oscillating cleanse, you hit the cool water before you’re done. Back-to-back users also feel it, since the tank needs time to reheat between visits.
That’s the trade-off with any tank-style seat. The upside is instant warmth at the start, with no cold burst while a heater ramps up. If you want more background on how heating types differ, my warm water bidet guide walks through it.
What Does the S5 Spec Sheet Promise?
The S5 spec sheet lists an instantaneous ceramic heater with continuous warm water and an adjustable water temperature range of 95 to 104°F. Instantaneous water heating works like a tiny tankless water heater: water passes over the heating element and warms on the way to the wand.
On paper, that means endless warm water for as long as you run the spray. Five seconds or two minutes, the temperature should hold at your setting.
Since I haven’t tested the S5 myself, I can’t give you a measured cool-down point. I can tell you that continuous warm water is exactly what the C5 lacked, and it’s the main reason I’d steer a new buyer to the S5.
Cleansing Spray: What Stayed the Same
The spray experience carries over almost unchanged, and both seats share TOTO’s bowl and wand cleaning tech. If the C5’s wash felt right to you, the S5’s should feel familiar.
How Do the Spray Rates Compare?
My C5 measured about 0.11 gallons per minute (0.43 liters per minute) on high, with an aerated spray that felt fuller than the number suggests. TOTO mixes air into the stream, so a small amount of water covers a decent area.
The S5 spec sheet lists:
- Rear wash: 0.07 to 0.11 gal/min
- Front wash: 0.08 to 0.11 gal/min
The top end lines up with what I measured on the C5. So the S5 maxes out at roughly the same volume, with the added benefit that the water stays warm the whole time. Low-flow is normal for TOTO; if you want a hard-hitting jet, neither seat is built for that.
Which Cleaning Features Do Both Seats Have?
Both seats include the same three hygiene features, based on my C5 testing and the S5 spec sheet:
- PREMIST bowl spray: Mists the bowl before use so waste is less likely to stick. On my C5, this cut down how often I had to scrub the bowl.
- EWATER+ wand cleaning: Rinses the wand with electrolyzed water before and after use.
- CLEAN RESIN coating: Listed on the S5 spec sheet as the seat surface material.
One spec note: EWATER+ on the S5 covers the wand. Bowl-level EWATER+ sits higher up TOTO’s lineup with the Washlet S7. For routine upkeep on either seat, my complete guide to cleaning a bidet covers the nozzle and filter steps.
Presets, Remote and Nightlight
The S5 doubles the saved user settings and adds a nightlight, two upgrades shared bathrooms will notice. Both seats use a wireless remote, so the basic control experience stays similar.
How Much Do Saved Settings Matter?
The C5’s wireless remote stored two user presets. In a two-person household, that worked fine for me: one press loaded water temperature, pressure, and nozzle position.
The S5 spec sheet lists four user presets, plus a docking station for the remote. For a family of three or four, that’s a meaningful jump. Without a preset, each person has to re-adjust pressure and position every visit, which gets old fast with kids or guests resetting things.
If it’s just you, two presets is plenty and this upgrade barely registers. If four people share one bathroom, it’s one of the better reasons to pick the S5.
Is the S5’s Nightlight Useful?
My C5 had no nightlight, and I missed one on late-night trips. I ended up flipping on the vanity light, which is harsh at 2 a.m.
The S5 spec sheet includes an LED nightlight. A soft glow near the bowl is enough to aim and sit without waking yourself up fully. It’s a small feature, but it’s the kind you use every single night once you have it.
For kids’ bathrooms and older family members, I’d call the nightlight a practical safety add rather than a gimmick. It saves you from buying a plug-in night light and finding an outlet for it.
Design and Fit
The S5 fits more toilets than the C5 because it comes in round as well as elongated, and its seamless seat should be easier to wipe down. Both are electronic bidet toilet seats that bolt onto an existing bowl and need a nearby outlet.
Will It Fit Your Toilet?
Here’s how sizing breaks down:
- C5 (SW3084#01): Elongated only, in the version I tested.
- S5 (SW3446#01 elongated): Elongated in Cotton White and Sedona Beige, per the spec sheet.
- S5 round: Available in Cotton White.
So round-bowl owners finally get a mid-range TOTO option with these features. Before buying either size, measure from the center of the seat bolts to the front edge of the bowl. Elongated bowls typically run about 18.5 inches; round bowls are closer to 16.5.
You’ll also need a GFCI outlet within reach. The S5 spec sheet lists a 3.93-foot power cord, so plan on an outlet within about four feet of the toilet. If you’re pairing a seat with a TOTO bowl, my guide to bidets for TOTO toilets covers fit details. TOTO also sells Washlet+ sets that pair specific seats with matching toilets for a cleaner connection.
What Makes the S5 Easier to Clean?
The S5 spec sheet calls out a seamless seat. On my C5, the seat had a seam where the top and bottom halves met, and that’s where grime collected. I’d run a damp cloth or old toothbrush along it every week or so.
A seamless design removes that crevice. Combined with the CLEAN RESIN surface, the S5 should need less detail cleaning around the seat edges. I can’t confirm long-term results since I haven’t lived with one, but losing the seam fixes a real annoyance I had with the C5.
Dryer, Heated Seat and Deodorizer
These comfort features are close to a wash between the two seats. The S5 brings published specs for each, while the C5 delivered all three in my testing.
Does the S5 Improve Everyday Comfort?
From the S5 spec sheet:
- Warm air dryer: 95 to 140°F, 3 settings, 8.83 cfm airflow
- Heated seat: 82 to 97°F
- SoftClose seat and lid
- Automatic air deodorizer
Those are solid numbers for a mid-range seat, but they don’t read like a big leap. The real comfort gain on the S5 is the continuous warm water, which I covered above. The dryer and heated seat look like refinements of what the C5 already did well.
A tip that applies to any bidet dryer: give it a couple of minutes and use the highest temperature setting. Low settings take noticeably longer. If drying speed is your top priority, my roundup of the best bidets that have dryers compares stronger options.
Which Features Are Already on the C5?
My C5 tested well in this area:
- Warm-air dryer: Good performance for its class. I could finish hands-free with some patience.
- Heated seat: Comfortable and consistent, especially in winter.
- Deodorizer: Kicked on automatically and handled bowl-level odor.
- SoftClose lid: Quiet and smooth.
So if comfort features are what you love about your C5, you aren’t missing much by keeping it. These aren’t the reason to upgrade.
Energy Use
An instant heater should cost less to run because it only heats water when you use the bidet. A tank heater like the C5’s keeps a reservoir warm around the clock so it’s ready the moment you sit down.
Does On-Demand Heating Save Electricity?
The logic is straightforward. The C5 holds a small tank of water at temperature all day, losing a bit of heat and topping it off. The S5 heats water only during a wash, then goes idle.
The S5 spec sheet lists a power rating of 1,271 watts, with a 1,426-watt maximum. That’s a high draw, but only for the seconds the heater runs. Brief high-power bursts generally add up to less than constant low-level warming.
I haven’t metered the S5 against my C5, so I won’t give you a dollar figure. Expect the savings to be modest either way; a bidet seat is a small slice of a household’s electric bill compared with HVAC or a water heater.
How Do the Energy-Saving Modes Work?
On my C5, power-saving behavior was simple: the seat’s power mode kicked on 10 seconds after I stood up and ran for one minute before settling down.
The S5 spec sheet lists an automatic energy saver mode. On TOTO seats with this feature, the seat learns when the bathroom tends to go unused and lowers the seat temperature during those hours. There’s also a manual energy saving mode on TOTO remotes that shuts heating off for a set block of hours each day.
A practical tip for either seat: turn the seat heat down a notch or two in summer. The heated seat runs more often than the water heater, so that’s where small savings show up.
Should Current C5 Owners Upgrade?
Most C5 owners should keep their seat unless the short warm-water window bugs them. The S5 is the better product, but a working C5 still covers the essentials.
Is the Warm-Water Limit a Dealbreaker?
Ask yourself how long your typical wash runs. In my testing, the C5 stayed warm for about 30 seconds and ran cool by 40.
Upgrade to the S5 if:
- You regularly wash longer than 30 seconds
- You use front and rear wash in the same visit
- Two or more people use the seat back to back
- You use the bidet for postpartum care or hemorrhoid relief, where steady warmth helps
Keep the C5 if your washes are quick and you’ve never felt the cool-down. Also keep it if it’s under warranty or running fine, since the rest of the feature set is nearly the same. A round-bowl swap or wanting a nightlight are nice bonuses, though on their own they don’t justify spending $700.
What Does a New S5 Cost?
Bidet King lists the S5 at about $668 to $780, depending on size and color. Add an electrician if you don’t already have a GFCI outlet near the toilet.
For a C5 owner, that’s full price to fix one weakness. If your C5 is failing or out of warranty, the math changes, and the S5 is the natural replacement. If you’re open to other brands, a seat like the Alpha JX2 runs about $389, and I compared it in my Alpha JX vs TOTO C5 breakdown. Older TOTO comparisons like the TOTO S550e vs C5 can also help if you’re weighing a step up in the lineup.
S5 vs. K300: Which TOTO Mid-Range Seat Should You Buy?
The K300 is my preferred TOTO mid-range seat, and it’s worth a look before you commit to the S5. Both use an instant heater for continuous warm water, and the K300 lists for about $699 to $725, which lands in the same range as the S5.
Here’s how they split:
- Pick the S5 if you want four user presets, a nightlight, the seamless CLEAN RESIN seat, or a round-bowl option, based on its spec sheet.
- Pick the K300 if you find it at a better price. Its core wash, warm water, and heated seat are the reasons I like it.
The K300 uses two user presets, which is plenty for couples. Bigger households lean S5.
If you want to see how the K300 handles the same warm-water problem the C5 had, my TOTO C5 vs K300 comparison covers it, and my TOTO K300 review goes deeper on daily use. Buyers eyeing more features above both can look at the Washlet S7, which adds bowl-level EWATER+ and a slimmer profile at a higher price.
Choosing the S5 or Keeping Your C5
The S5 is the clear choice for new buyers. It keeps the C5’s PREMIST, EWATER+, heated seat, dryer, and deodorizer, then adds continuous warm water, four presets, a nightlight, a seamless seat, and a round size, all per TOTO’s spec sheet.
My C5 testing showed warm water starting above 100°F and running cool at 40 seconds. That’s the one gap the S5 is built to close.
If you own a C5 that works and your washes are short, keep it. If the cool-down bothers you or your seat is failing, the S5 at about $668 to $780 from Bidet King is the replacement I’d buy, with the K300 as the alternative when its price comes in lower.
Ready to order? You can check current prices on the TOTO Washlet S5 at Bidet King here (affiliate link). Bidet King handles TOTO warranty claims and support, which is why I buy there.