TOTO Costco Washlet vs Washlet S5
The TOTO Washlet sold at Costco is model T1SW2491, a Costco-only elongated seat that heats water in a small tank. The Washlet S5 (SW3446 elongated) heats water instantly as it flows, so the warm spray doesn't run out, and adds EWATER+ wand cleaning and a night light. Both have PREMIST, a heated SoftClose seat, a warm-air dryer, a deodorizer and a wireless remote with memory for four users. The short version: the Costco seat is the value buy if your washes are short and you like Costco's returns; the S5 is the better seat if you want warm water for the whole wash.
Search 'is the TOTO bidet at Costco good?' and you mostly find retailer videos and Reddit threads. This comparison sticks to what TOTO and Costco publish: Costco's listing and TOTO's T1SW2491 spec sheet for the Costco model, and TOTO's S5 page plus our S5 review for the S5. Where a claim comes only from reviewers, we say so.
This comparison is researched, not tested by us: we compared the manufacturer's and retailer's published specs and read them against owner and reviewer reports. We've left prices out because Costco and Amazon both change them often. Check both on the day you buy.
| TOTO Costco Washlet (T1SW2491) | TOTO Washlet S5 | |
|---|---|---|
| Water heating | Tank-type heater (TOTO spec). A long wash can run cooler as the tank empties | Instantaneous tankless heater: warm water for the whole wash |
| Wand cleaning | Not listed on the Costco spec sheet | EWATER+ electrolyzed water cleans the wand before and after each use |
| Bowl pre-mist | PREMIST | PREMIST |
| Remote | Wireless remote with 4-user memory and a docking station | Wireless, wall-mountable remote with 4-user memory |
| Seat and dryer | Heated SoftClose seat; warm-air dryer with 3 temperature settings | Heated SoftClose seat; warm-air dryer with 3 temperature settings |
| Night light | Not listed on the Costco spec sheet | Yes |
| Size (Costco listing / TOTO) | 15.25 in W × 20.94 in D × 6.63 in H (Costco listing) | TOTO says the S5 is 19% slimmer than the C5 it replaced |
| Where to buy and returns | Costco only; covered by Costco's return policy | Amazon, plumbing retailers and TOTO dealers; the retailer's return policy applies |
| Warranty | Check the warranty card and Costco's listing for the current terms | 1-year limited warranty (per our S5 review) |
When to choose each
Choose the Costco Washlet (T1SW2491) if you already shop at Costco, your washes are short, and you value Costco's generous returns. You still get TOTO's PREMIST, a heated SoftClose seat, a dryer, a deodorizer and a four-user remote. The trade-off is the tank: if you like long, warm washes, or several people use the toilet back to back, the water can cool before you're done.
Choose the TOTO Washlet S5 if warm water from start to finish matters to you. The tankless heater doesn't run out, EWATER+ keeps the wand cleaner with no effort, and you get a night light and a wall-mountable remote. It's the better seat for households with several users and for anyone who has been disappointed by a tank seat going cold.
Read the full review →Our verdict
Frequently asked questions
What is the difference between the TOTO Costco Washlet and the S5?
The TOTO Washlet sold at Costco (model T1SW2491) heats water in a small tank, so a long wash can run cooler, while the Washlet S5 heats water instantly for a warm spray that doesn't run out. The S5 also adds EWATER+ wand cleaning and a night light, which aren't listed on the Costco model's spec sheet. Both have PREMIST, a heated SoftClose seat, a warm-air dryer, a deodorizer and a four-user wireless remote.
Is the TOTO bidet at Costco good?
It's a solid TOTO seat with the core features most people want: warm wash, heated seat, dryer, PREMIST and a remote with user memory. Its main limitation is the tank heater, so it suits shorter washes best. Costco's return policy is a real advantage if you're unsure.
Is the Costco TOTO Washlet the same as the C5?
It's a separate, Costco-only model number (T1SW2491). Its spec sheet lists a tank-type heater and four-user remote, which overlaps with the older C5's feature set, but compare the current spec sheets rather than assuming they're identical. See our S5 review for how the S5 differs from the C5.
Does the Costco Washlet run out of warm water?
TOTO's specs describe a tank-type heater, and tank seats can cool during a long wash. Some retailer videos report only a short burst of warm water; we couldn't confirm a figure from TOTO's own documents. If that matters to you, the tankless S5 avoids the issue.
Do both need an outlet?
Yes. Both are electric seats and need a grounded GFCI outlet near the toilet. If you don't have one, see bidet without an outlet.
Which fits more toilets?
Both are elongated seats in these models. Check your bowl shape and the distance from the bolt holes to the tank before buying; see how to measure a toilet seat.