Milestone-Proposal:First Electronic Lavatory Basin 'Washlet', 1980

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Docket #:

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To the proposer’s knowledge, is this achievement subject to litigation? No

Is the achievement you are proposing more than 25 years old? Yes

Is the achievement you are proposing within IEEE’s designated fields as defined by IEEE Bylaw I-104.11, namely: Engineering, Computer Sciences and Information Technology, Physical Sciences, Biological and Medical Sciences, Mathematics, Technical Communications, Education, Management, and Law and Policy. Yes

Did the achievement provide a meaningful benefit for humanity? Yes

Was it of at least regional importance? Yes

Has an IEEE Organizational Unit agreed to pay for the milestone plaque(s)? Yes

Has an IEEE Organizational Unit agreed to arrange the dedication ceremony? Yes

Has the IEEE Section in which the milestone is located agreed to take responsibility for the plaque after it is dedicated? Yes

Has the owner of the site agreed to have it designated as an IEEE Milestone? Yes

Year or range of years in which the achievement occurred:


Title of the proposed milestone:

First Electronic Lavatory Basin 'Washlet', 1980

Plaque citation summarizing the achievement and its significance:

‘Washlet’ is a registered trademark of the Japanese housing equipment manufacturer TOTO Ltd., used for its business of marketing electronic lavatory basins with water spray feature. Released in June 1980, a total of more than 50 million 'washlets' had been sold by 2019. Furthermore, the lavatory basins including 'washlets' were installed in 80.2% of Japanese households as of March 2020.

200-250 word abstract describing the significance of the technical achievement being proposed, the person(s) involved, historical context, humanitarian and social impact, as well as any possible controversies the advocate might need to review.

IEEE technical societies and technical councils within whose fields of interest the Milestone proposal resides.

In what IEEE section(s) does it reside?

Fukuoka Section

IEEE Organizational Unit(s) which have agreed to sponsor the Milestone:

IEEE Organizational Unit(s) paying for milestone plaque(s):

Unit: Fukuoka Section
Senior Officer Name: Masahito Shoyama

IEEE Organizational Unit(s) arranging the dedication ceremony:

Unit: Fukuoka Section
Senior Officer Name: Masahito Shoyama

IEEE section(s) monitoring the plaque(s):

IEEE Section: Fukuoka Section
IEEE Section Chair name: Masahito Shoyama

Milestone proposer(s):

Proposer name: Isao Shirakawa
Proposer email: Proposer's email masked to public

Please note: your email address and contact information will be masked on the website for privacy reasons. Only IEEE History Center Staff will be able to view the email address.

Street address(es) and GPS coordinates in decimal form of the intended milestone plaque site(s):

Street Address: TOTO Museum of TOTO Ltd., 2-1-1 Nakashima, Kokurakita-ku, Kitakyushu, 802-8601 Japan; GPS coordinates: N 33.87491, E 130.87273

Describe briefly the intended site(s) of the milestone plaque(s). The intended site(s) must have a direct connection with the achievement (e.g. where developed, invented, tested, demonstrated, installed, or operated, etc.). A museum where a device or example of the technology is displayed, or the university where the inventor studied, are not, in themselves, sufficient connection for a milestone plaque.

Please give the address(es) of the plaque site(s) (GPS coordinates if you have them). Also please give the details of the mounting, i.e. on the outside of the building, in the ground floor entrance hall, on a plinth on the grounds, etc. If visitors to the plaque site will need to go through security, or make an appointment, please give the contact information visitors will need. TOTO Museum of TOTO Ltd.

Are the original buildings extant?

The original building of TOTO Museum is extant [1].

Details of the plaque mounting:

The plaque will be displayed in a cabinet placed in TOTO Museum.

How is the site protected/secured, and in what ways is it accessible to the public?

The plaque in TOTO Museum is protected by TOTO Ltd. and accessible to the public by permission of TOTO Ltd.

Who is the present owner of the site(s)?

Mr. Noriaki Kiyota, President of TOTO Ltd.

What is the historical significance of the work (its technological, scientific, or social importance)? If personal names are included in citation, include justification here. (see section 6 of Milestone Guidelines)

The historical significance of TOTO’s commercialization of ‘washlets’ is briefly stated in what follows.

1. Historical Background of TOTO's Commercialization of 'Washlets'.

The business model of TOTO Ltd. in the 1960s was to import American 'wash air seats' for domestic sales, which were mainly sold to hospitals for medical purposes. TOTO began domestic production of 'wash air seats' in 1969, but they were initially expensive and sometimes caused scaling injuries because of poor regulation of water temperature. Thus, TOTO had to continue its own research and development, surveying 300 male and female employees to determine the appropriate spray positions, because there were no biometric statistics available [2,3].

2. TOTO's Efforts of Commercializing 'Washlets'.

Banking on the prospect that 'wash air seats' would be widely spread in Japan, TOTO began to commercialize its own improved products in 1980 by the brand name of 'washlets', for which two models of 'G series ("Gorgeous")' and 'S series ("Standard")' were developed. The former could store warm water and had a bidet and a dryer function as well as a lavatory basin warming facility, while the latter instantly turned cold water into warm water and was equipped with a bidet and a lavatory basin warmer function. These two series have remained the basic product models until now, along with a compact series introduced in 1993. The models initially included a regular and an elongated size, depending on the configuration of the lavatory basin, but were replaced by single-sized types in February 2012 with a few exceptions such as products for hotel usage [2,3].

3. TOTO's Commercial Activities for 'Washlets'

Recognizing its pioneering role, in July 2012 the initial model 'G series' was certified as item number 55 of Mechanical Engineering Heritage by the Japan Society of Mechanical Engineers [2,3]. TOTO had since been devoted to enhancing functionalities until in 2019 the accumulated total of 'washlets' grew to such a great amount of 50 million products that the unit cost decreased enough to enable mass production. Thus, the household penetration rate of the lavatory basins including 'washlets' in Japan reached 80.2% as of March 2020 [2].

What obstacles (technical, political, geographic) needed to be overcome?

In the early commercialization phase, ‘washlets’ encountered several obstacles, which were overcome as outlined below.

(1) There once occurred an unexpected happening in which some washlets activated regardless of whether the user was seated or not. To cope with such an accident, TOTO has introduced a sensor that detects whether the user is seated or not, throughout the product lineup. To make further improvements, TOTO has added new functions including toilet lids that automatically open and close, toilet cleansing, deodorant, gas absorbent, and air refresher [3].

(2) There are numerous features with which washlets have had to be furnished, such as blow dryer, seat warming, massage options, water jet adjustments, automatic lid opening, automatic flushing, wireless control panel, room heating, and air conditioning for the room. These features should be arranged to be accessed by a control panel attached to the lavatory basin or mounted on a nearby wall [4].

(3) Most high-tech lavatory basins urge water temperature and water pressure to be adjusted to match the preferences of the user. On the subject of water temperature, researchers in Japan have found that most users prefer a water temperature slightly above body temperature, with 38°C considered optimal, while on the subject of water pressure, the nozzle position has to be manually adjusted forward or aft [4].

(4) A number of measures should be taken associated with operating the cleansing features. Especially, for antibacterial and antifouling purposes, the nozzle must be designed at such an angle that the water does not splash back on the inside of the lavatory basin, and the nozzle itself is to be washed with warm water when it is stowed away or before use [3].

What features set this work apart from similar achievements?

‘Washlets’ have distinctive features as outlined below.

1. TOTO’s Success in Commercializing 'Washlets'

Some lavatory basins in Japan are more elaborate than those commonly found in other developed nations. European countries often have a lavatory basin and a bidet separate, while Japan combines an electronic bidet with the lavatory basin. The age of the high-tech lavatory basin in Japan started in 1980 with the introduction of ‘Washlet G Series’ by TOTO Ltd., and since then the product name ‘washlet’ has been used not only as a brand name of TOTO but also to refer to all types of Japanese high-tech lavatory basins. As of 2002, almost half of Japanese homes used such lavatory basins, and moreover, as of March 2020, lavatory basins were installed in 80.2% of Japanese households [2,4], as already stated.

2. Numerous Features to be Furnished 

While the lavatory basin looks like a western-style toilet, there are numerous features, such as blow dryer, seat warming, water jet adjustments, automatic lid opening, automatic flushing, wireless control panel, room heating, and air conditioning for the room, as already stated. Each of these features should be accessed by a control panel attached to the lavatory basin or mounted on a nearby wall [4].

3. Adjustment of Water Temperature and Water Pressure

High-tech lavatory basins usually require water temperature and water pressure to be adjusted according to the user's preferences. As for the water temperature, numbers of researchers have already found that most users prefer a water temperature, with 38°C regarded as optimal, while as for the water pressure, the nozzle position should be manually adjusted [4], as already stated.

4. Future Developments

Recently, researchers have added medical sensors into lavatory basins, which can measure not only the blood sugar of urine but also the pulse, blood pressure, and the body fat content of the user. Talking lavatory basins that greet the user have also started being made. Other measurements are currently being researched. The data may be automatically sent to a doctor through a built-in internet-capable cellular telephone. A voice-operated lavatory basin that understands verbal commands is under development. TOTO, Panasonic, and other companies also produce portable, battery-operated 'travel washlets', which must be filled with warm water before use. Eventually, Japanese companies have commercialized some of the most advanced, highest tech lavatory basins in the world [4].

Supporting texts and citations to establish the dates, location, and importance of the achievement: Minimum of five (5), but as many as needed to support the milestone, such as patents, contemporary newspaper articles, journal articles, or chapters in scholarly books. 'Scholarly' is defined as peer-reviewed, with references, and published. You must supply the texts or excerpts themselves, not just the references. At least one of the references must be from a scholarly book or journal article. All supporting materials must be in English, or accompanied by an English translation.


[1] "TOTO Museum"; (in Japanese)

[2] "Washlet"; (in Japanese)

[3] "Washlet";

[4] "Toilets in Japan";


1: Reference [1] was written in Japanese, for which English abstracts are briefed as follows: This article outlines the contents exhibited in TOTO Museum.

2: Reference [2] was written in Japanese with almost the same contents of Reference {3], and its English abstracts are itemized as follows: (1) overview, (2) brief history of TOTO’s commercialization of washlets, (3) functions of washlets, and (4) references.

Supporting materials (supported formats: GIF, JPEG, PNG, PDF, DOC): All supporting materials must be in English, or if not in English, accompanied by an English translation. You must supply the texts or excerpts themselves, not just the references. For documents that are copyright-encumbered, or which you do not have rights to post, email the documents themselves to Please see the Milestone Program Guidelines for more information.

Please email a jpeg or PDF a letter in English, or with English translation, from the site owner(s) giving permission to place IEEE milestone plaque on the property, and a letter (or forwarded email) from the appropriate Section Chair supporting the Milestone application to with the subject line "Attention: Milestone Administrator." Note that there are multiple texts of the letter depending on whether an IEEE organizational unit other than the section will be paying for the plaque(s).

Please recommend reviewers by emailing their names and email addresses to Please include the docket number and brief title of your proposal in the subject line of all emails.