The birth of the Mashimizu water purifier.

In 1983, the incident of drinking water poisoning of the Mitsubishi Rayon president on a business trip in Mexico led to the development of hollow-fiber membrane filter a portable water purifier “Mashimizu” in which “hollow-fiber membrane filter” is mounted. This opened the door to the launch of innovative household water-purifying systems. Indeed, in the following year, the household countertop water purifiers “Cleansui S” and “Cleansui D” were introduced to the market. In 1989, Cleansui Petit that is the first faucet-mounted water purifier in our Cleansui series achieved explosive sales. This stimulated the growth and expansion of our lineup.

The filtration of an orange juice sample.

Filtration via an activated carbon filter only.
Filtration using a system comprising activated carbon and hollow-fiber membrane filters. Our system removed the organic matter in the orange juice sample; thus, the sample turned into a transparent liquid.

Launch of “Mashimizu,” the world’s first hollow-fiber membrane filter-based portable water purifier (1984).

Mashimizu was debuted in 1984.

After being recognized in the medical care industry, the hollow-fiber membrane became a focus of attention. Since then, hollow-fiber membranes have been used in various applications, leading to the development of a water purifier. The development of water purifiers adopting hollow-fiber membranes started after the drinking water poisoning incident, which was experienced by a previous Mitsubishi Rayon president during a business trip in Mexico. This president dreamed of “Providing everyone with safe drinking water anywhere without having anxiety.” After returning to Japan, the president ordered the development of a portable water purifier. In the following year of 1983, the world’s first hollow-fiber membrane filter portable water purifier called “Mashimizu” was put on the market.

1984 birth of our water purifier brand “Cleansui.”

The Cleansui D, which debuted in 1984.

After the release of the portable water purifier “Mashimizu,” our development team focused on the development of drinking water systems for use in the home. The team developed and introduced the household countertop water purifiers of “Cleansui S” and “Cleansui D” to the market in October of 1984. Then, we introduced a series of products in the umbrella brand name of Cleansui. Our technologies are currently being applied to various areas including products for use in residential and commercial facilities. They have also contributed to the world, especially in the fields of medical care and environment.

About Cleansui

About the hollow-fiber membrane

In the 1970s, a factory of Mitsubishi Rayon (now Mitsubishi Chemical) that developed fibers for filtering water and blood encountered a problem related to the opaque polypropylene fibers produced. A researcher from this company studied the fibers under a microscope and observed numerous pores on the walls of straw-like hollow fibers. The researcher improved the process, and succeeded in developing polypropylene “hollow-fiber membrane filters.” Since then, hollow-fiber membrane filters have been used in wastewater treatment and medical care. Interestingly, they were used to make the first artificial lung device in 1978.

The birth of the Cleansui.

Award-winning designs

The aesthetic designs of the Cleansui products have attracted significant attention, and have bagged several awards in domestic (Japan) and global design competitions. The brand received “the Red Dot Award,” which is one of the largest design award in the world for three consecutive years (2018–2020). In 2018, we received the Red Dot Award in Product Design for the Cleansui Shigaraki JP100-C water purifier. This purifier was the first product from the project “Cleansui Knows Japanese Crafts,” a collaboration with skilled craftsmen who followed Japanese traditions. In the following year of 2019, we received the Red Dot Award in Brands & Communication Design for our corporate identity (CI) of “Cleansui,” which was produced by graphic designer Taku Satoh in 2009. In 2020, we received our second Red Dot Award in Product Design for the faucet-mounted water filter “Cleansui CSP901,” which was designed by product designer Fumie Shibata.

Cleansui should be the preferred brand by customers.

There are several reasons for selecting Cleansui products over other water purifiers in the market. First, Cleansui high-performance water purifiers with innovative hollow-fiber membrane filter technology can absolutely remove the 17 and 2 substances designated by the JIS S 3201 (Testing methods for household water purifiers) and Japan Water Purifier Association, respectively. Meanwhile, they selectively retain the beneficial minerals in tap water. Then, their sophisticated yet user-friendly design is attractive. Next, the low cost-performance ratio of the faucet-mounted purifier (one cartridge) that produces purified water equivalent to 450 2-liter plastic bottles of water has been unrivaled. Finally, we have a substantial after-sales support department that effectively facilitates the periodic delivery of replacement cartridges and customer care service to guide customers on the proper and carefree use of our products.