Many Toto employees assisted in the development of the Washlet by serving as the subjects of various tests. They actually sat on the toilet seat to help discover the ideal conditions for cleansing, including the nozzle length and position, spraying angle, and water temperature. In order to prevent scalding from hot water, tests were also held to find out what the highest bearable temperature was. Employees both young and old took part, and some unlucky people could be heard screaming in pain at the heat of the water. After much experimenting, the developers settled on 38 degrees Celsius (100 degrees Fahrenheit), slightly above human body temperature, as the most comfortable water temperature.
Great improvements have been made since that time, and Washlets today have many amazing features. Heated seats have become standard, and the newest models can oscillate the water pressure, automatically absorb the smell after a user leaves the seat, and even warm up the entire lavatory at a preset time.
A television commercial for the Washlet that Toto first aired in 1982 used the tag line, "Your tush wants to be washed, too." This struck a chord with the public, and monthly sales shot up to more than three times the figures recorded in the first year. Today, in addition to the Washlet, consumers can choose from many different brands, including Inax Corp.'s Shower Toilet. The results of a survey by the Japanese government indicate that as of the end of March 2002, nearly one in two Japanese homes had warm-water cleansing toilet seats.