TOTO WASHLET vs Brondell vs Bio Bidet: Which Bidet Seat to Buy, How to Install It, and What the Research Says

In Japan, more than 80% of households have a warm-water bidet seat (Japan's Ministry of Economy, Trade and Industry, 2024). It started with TOTO, which launched the first WASHLET in June 1980 with a warm-water wash, a warm-air dryer and a heated seat (TOTO USA). In the US, TOTO's seats now sit next to American brands such as Brondell and Bio Bidet, and they all promise the same things. This guide compares six popular seats on the spec that actually matters, then covers what most buying guides skip: how installation really goes, what new owners ask in the first week, and what research says about bidets and health.

Six seats side by side

All six wash front and rear with adjustable warm water, and all heat the seat. Where they differ: how they heat the water, whether there is a warm-air dryer and deodorizer, and whether you control them from a side panel or a remote. TOTO also adds two features from Japan that the others don't: PREMIST, which mists the bowl before use so waste is less likely to stick, and EWATER+, which cleans the bowl and wand with electrolyzed tap water after each use (TOTO USA). Kohler makes a well-known seat too, the PureWash E930, but on Amazon it was only available from third-party sellers in small quantities when we checked, so it isn't in this comparison.

The spec that matters most: instant vs tank warm water

This is the difference people notice every day. A tank seat keeps a small reservoir of warm water. Brondell says its tank models give 20 to 40 seconds of warm water and then take 3 to 4 minutes to reheat; TOTO likewise notes that reservoir models need time to reheat after extended use. That is fine for one quick wash, but a long wash, or two people using the toilet back to back, can end with cool water. An instant seat heats water as it flows, so it never runs out. If more than one person will use it, or you live somewhere with cold tap water, instant heating is worth paying for.

Which seat to buy

The drawings below are simple illustrations, not product photos. Prices and stock on Amazon change often, so check the product page for current details.

TOTO WASHLET S2: the Japanese original, done right. It heats water instantly, warms the seat, dries you with warm air and filters odors, and it is the least expensive WASHLET with both PREMIST and EWATER+ for the bowl and the wand. If you want the same kind of seat found in most Japanese homes, start here. See our full TOTO WASHLET guide for the rest of the lineup.

Brondell Swash 1400: the remote-controlled alternative. Brondell lists ceramic instant water heating, so the warm water doesn't run out, with air-mixed spray and adjustable pressure through dual stainless steel nozzles. A programmable remote, an LED nightlight, a quiet slow-close lid, a carbon deodorizer and a self-clean cycle before and after use round it out. It comes with a 42-inch power cord.

Bio Bidet BB2000: every comfort feature, with a remote. Bio Bidet lists endless warm water, a warm-air dryer, a heated seat, a nightlight and a built-in deodorizer, with wash temperature, pressure and position set from a wireless remote, and says it is designed for DIY installation.

Bio Bidet DLS: another instant option. Bio Bidet lists unlimited warm water and a stainless steel nozzle for front and rear washing, with adjustable pressure and temperature.

TOTO WASHLET A2: the budget TOTO. It keeps warm water in a small tank, so the warm wash is limited, and it skips the dryer and deodorizer. In return you get TOTO's build and a heated seat at a lower price. Good for a guest bathroom or a single user who washes quickly.

Brondell Swash SE400: a tank seat with a dryer. Brondell's SE400 uses a tank, but adds a warm-air dryer, an oscillating nozzle with wash, massage and pulse options, an LED light and an eco mode, all controlled from a side arm.

How to install a bidet seat

Most people install a bidet seat themselves with basic tools. The hard part is usually not the seat, but what has to be in place before you buy it.

Things that catch people out: there is no outlet near the toilet (adding one is a job for an electrician); the outlet isn't GFCI-protected; the old supply line is rigid; or the seat is the wrong shape for the bowl. Some French-curve or one-piece toilets don't fit standard seats, so check the maker's fit chart. TOTO also warns not to use its energy-saver feature if the room can drop to freezing.

What new owners ask in the first week

These are the questions that come up most in TOTO's product FAQ and manuals (TOTO USA FAQ), and most have simple answers.

• "The water was cold at first." On a tank seat, the reservoir needs time to warm up the first time and to reheat after long use. In a cold bathroom or with cold tap water, the first spray can feel cool. Check the temperature setting and whether energy-saver mode is on.
• "The seat feels cold sometimes." That is usually the energy saver. TOTO's automatic energy saver learns when the toilet is rarely used, over about 10 days, and lowers the seat temperature then. Turn it off or set a timer instead.
• "It only works some of the time." TOTO's FAQ points to a loose plug, a tripped GFCI, unstable water supply, the seat sensor not detecting you, or energy-saving settings.
• "How do I keep the nozzle clean?" The wand cleans itself before and after each wash on these seats, and many models have a button that extends the wand without spraying so you can wipe it.
• "Does it use much electricity?" Standby use is small. One TOTO manual lists about 1.6 W in normal mode for the deodorizer; heating uses more while it runs.

Does a bidet actually help? What the research says

Bidet seats are often sold as healthier, but the evidence is more mixed than the marketing. Here is what studies have found, in plain terms. This is general information, not medical advice.

• Hemorrhoids: a systematic review found that habitual bidet use did not change the odds of developing hemorrhoids or hemorrhoid symptoms (systematic review, 2022).
• After hemorrhoid surgery: a randomized trial found an electronic bidet with gentle water flow was as good as a warm sitz bath for pain a week after surgery (BIDLOW trial).
• Itching: the same review found habitual use may increase the odds of anal itching (pruritus ani), and case reports describe burns and small tears from very hot or strong sprays.
• Women's health: a one-year follow-up web survey in Japan linked habitual use with a higher rate of bacterial vaginitis, though the authors say the numbers were too small for a firm conclusion (Japanese follow-up survey).

The practical takeaway: a bidet seat is a comfort and cleanliness upgrade, not a treatment. Use moderate temperature and pressure, don't overdo it, and let the front-wash setting do its job gently. Bidet makers also point out that washing with water reduces how much toilet paper you need.

Which one suits you?

• You want the Japanese original: TOTO WASHLET S2.
• You prefer a remote: Brondell Swash 1400 or Bio Bidet BB2000.
• Another instant warm-water option: Bio Bidet DLS.
• One user, quick washes, lower budget: TOTO WASHLET A2.
• A tank seat with a dryer: Brondell Swash SE400.
• No outlet near the toilet: see bidet attachment vs electronic seat.