Life Hacks in Japan

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"Life in Japan 2023" We have found the manufacturer of the first high-performance water purifier!

Mitsubishi Chemical, Brita, Toray, Panasonic, and various other manufacturers, but there is one manufacturer to buy.

Food Safety Standards

If you are in a hurry, please click on the product comparison table in the table of contents. In a nutshell, only drinking and tap water that has passed strict criteria is on the market.

First of all, it is necessary to comply with the food-specific standards set forth by the Ministry of Health, Labor and Welfare for the production of water as a product in the manufacturing of food and beverages. Among them, the standards to be met by "mineral waters (soft drinks made solely from water) that are sterilized or sanitized" are as follows. (You can scroll to the right.)

(data) item standard (data) item standard
antimony (Sb) 0.005 mg/l or less Cis-1 , 2-dichloroethylene and trans-1 , 2-dichloroethylene 0.04 mg/l or less as the sum of cis- and trans-bodies
cadmium (Cd) 0.003 mg/l or less dibromochloromethane 0.1 mg/l or less
mercury 0.0005 mg/l or less bromic acid 0.01 mg/l or less
selenium (Se) 0.01 mg/l or less nitrous nitrite 0.04 mg/l or less
copper 1mg/l or less Nitrate nitrogen and nitrite nitrogen 10 mg/l or less
lead (the metal) 0.05 mg/l or less total trihalomethane 0.1 mg/l or less
barium (Ba) 1mg/l or less tetrachloroethylene 0.01 mg/l or less
arsenic (As) 0.01 mg/l or less trichloroethylene 0.004 mg/l or less
manganese (Mn) 0.4 mg/l or less toluene 0.4 mg/l or less
hexavalent chromium 0.05 mg/l or less fluorine (F) 2 mg/l or less
Cyanogen (cyanide ion and cyanide chloride) 0.01 mg/l or less bromodichloromethane 0.03 mg/l or less
chloric acid 0.6 mg/l or less bromoform 0.09 mg/l or less
chloroform 0.06 mg/l or less benzene 0.01 mg/l or less
residual chlorine 3 mg/l or less boron (B) 5 mg/l or less
chlorous acid 0.6 mg/l or less formaldehyde 0.08 mg/l or less
carbon tetrachloride (CCl4) 0.002 mg/l or less Organic matter, etc. (total organic carbon) 3 mg/l or less
1 , 4-Dioxane 0.04 mg/l or less taste No abnormality.
dichloroacetonitrile 0.01 mg/l or less bad smell No abnormality.
1 , 2-Dichloroethane 0.004 mg/l or less chromaticity 5 degrees or less
dichloromethane 0.02 mg/l or less turbidity Less than 2 degrees


Tap Water Quality Standards

Next, let us look at the standards for tap water. According to the Waterworks Law, there are 51 water quality standards, 11 more than the standards for soft drinks.

(data) item standard (data) item standard
General bacteria Number of settlements formed in 1ml of test water is less than 100 total trihalomethane 0.1 mg / L or less
Escherichia coli (E. coli) Not to be detected trichloroacetic acid 0.03 mg / L or less
Cadmium and its compounds 0.003 mg / L or less with respect to the amount of cadmium bromodichloromethane 0.03 mg / L or less
Mercury and mercury compounds Less than 0.0005 mg/L with respect to the amount of mercury bromoform 0.09 mg / L or less
Selenium and its compounds Less than 0.01 mg / L with respect to the amount of selenium formaldehyde 0.08 mg / L or less
Lead and its compounds Less than 0.01 mg / L for the amount of lead Zinc and its compounds Less than 1.0 mg / L with respect to the amount of zinc
Arsenic and its compounds 0.01 mg / L or less with respect to the amount of arsenic Aluminum and its compounds Less than 0.2 mg/L with respect to the amount of aluminum
Hexavalent chromium compounds Less than 0.02 mg/L for the amount of hexavalent chromium Iron and its compounds Less than 0.3 mg/L with respect to the amount of iron
nitrite-nitrogen 0.04 mg / L or less Copper and its compounds Less than 1.0 mg/L in terms of copper content
Cyanide ion and cyanide chloride 0.01 mg / L or less with respect to the amount of cyanide Sodium and its compounds Less than 200 mg/L with respect to the amount of sodium
Nitrate-nitrogen and nitrite-nitrogen 10 mg / L or less Manganese and its compounds 0.05 mg / L or less with respect to the amount of manganese
Fluorine and its compounds 0.8 mg/L or less with respect to the amount of fluorine chloride ion 200 mg / L or less
Boron and its compounds 1.0 mg / L or less with respect to the amount of boron Calcium, magnesium, etc. (hardness) 300 mg / L or less
carbon tetrachloride (CCl4) 0.002 mg / L or less evaporation residue 500 mg / L or less
1,4-Dioxane 0.05 mg / L or less anionic surfactant 0.2 mg / L or less
Cis-1,2-dichloroethylene and trans-1,2-dichloroethylene 0.04 mg / L or less geosmin 0.00001 mg / L or less
dichloromethane 0.02 mg / L or less 2-Methylisoborneol 0.00001 mg / L or less
tetrachloroethylene 0.01 mg / L or less non-ionic surfactant 0.02 mg / L or less
trichloroethylene 0.01 mg / L or less phenol 0.005 mg / L or less in terms of phenol
benzene 0.01 mg / L or less Organic matter (total organic carbon (TOC)) 3mg / L or less
chloric acid 0.6 mg / L or less pH 5.8 to 8.6
chloroacetic acid 0.02 mg / L or less flavor No abnormality
chloroform 0.06 mg / L or less bad smell No abnormality
dichloroacetic acid 0.03 mg / L or less chromaticity 5 degrees or less
dibromochloromethane 0.1 mg / L or less turbidity Less than 2 degrees
bromic acid 0.01 mg / L or less (BLANK) (BLANK)

Water quality standard items and standard values (51 items)(Effective April 1, 2020)


The number of items in these water quality standards alone is surprising, but furthermore, the items are revised every year, indicating that they are bound by very strict laws.

Water supply is governed by the Water Supply Law enacted in 1957. Tap water must conform to water quality standards, and the Waterworks Law obliges water service providers and others to conduct water quality inspections.


Revisions have been made approximately every 10 years, but since the 2003 revision, the system has become a sequential revision system that is constantly reviewed according to the latest findings. As a result, items are added, deleted, and standards are revised almost every year.
Tap Water Quality Standards/Kanagawa Institute of Public Health News No.166


MUJI has also started a free tap water supply service. From the responses of private companies like these, we can assume that the idea that tap water is bad for the body is wrong.


Causes of Bad Tap Water

So what causes bad tap water even though it passes such strict standards?

Cause 1: Chlorine

Water supply is an infrastructure that stretches throughout Japan. During the long journey from the water purification facility to the faucet, chlorine, a gas with a distinctive taste and odor, is mixed in to prevent bacteria from growing. However, as written in the table above, the residual chlorine is set within a range that has no effect on the human body.

The Waterworks Bureau adjusts the appropriate residual chlorine concentration in order to supply safe and tasty water. Chalky odor may be detected due to changes in climate, physical condition, or sense of smell. However, please understand that this is proof that tap water is "safe tap water" that is not contaminated by bacteria.
Tottori City Waterworks Bureau


Cause 2: Metals such as iron, zinc, and copper

Today's water pipes are made of polyethylene, but in the past water pipes were made of metal. Therefore, metal may dissolve into the water pipes or rust may cause red water. However, as described below, small amounts will not affect health.

When iron is used in water distribution pipes and water supply pipes, the iron is oxidized by residual chlorine and becomes rust. This rust causes red water to appear when the water is first used. If red water appears first thing in the morning and subsides over time, the cause is probably the water supply pipes. This phenomenon is more common in older pipes.

If red (or brown) water comes out, flush for a while and use only after the color has disappeared. Accidentally taking a small amount by mistake is not a health hazard.
Kawasaki City Water & Sewerage Bureau: Waterworks Q&A


Cause 3: Aggravation in water storage tank

The Kagoshima City website stated the following

Most buildings over three stories high have a water tank, called a cistern, on the roof, above ground or underground. Once tap water is stored there, it is distributed to each household. If the amount of water used is too small for the capacity of the reservoir, the water will stay in the reservoir for a long time. When this happens, the water temperature rises and becomes lukewarm during the summer, and the water may taste bad. In addition, poor maintenance of rooftop cisterns can lead to the growth of mold and algae, resulting in bad water.


If the problem is caused by the cistern, it should be cleaned. For apartments and condominiums, please contact the owner or manager. Regardless of whether or not you drink tap water on a daily basis, it is water used to wash dishes and vegetables as well, so it is a problem that must be resolved.
When tap water tastes different from usual|Kagoshima City


This means that the water will be bad in older houses or buildings that are not well maintained. It also means that there are infrastructure issues regarding anything other than chalky water. If you are concerned, we recommend that you check and inquire through the city's website.

Effects of Water Purifiers

It has become clear that although there is no problem with the quality of tap water, the taste may be impaired due to residual chlorine or other infrastructure issues such as water pipes and storage tanks. Therefore, a water purifier is a device to further reduce impurities from tap water delivered to the home.

Many of you may be wondering, "How can a water purifier possibly be effective?" It is true that manufacturers' product pages are often full of information that favors their own company, but there is also information that can be trusted.

It is what is required to be clearly stated in laws, ordinances, and standard standards. For example, there is a rule for the indication such as "5 minutes walk from the station" written in advertisements for rental properties. Specifically, the Fair Competition Code for Real Estate Indication stipulates that the distance from the station should be divided by 80 meters, calculating that it takes one minute to walk 80 meters.

Various laws also govern water purifiers, which are summarized on the Consumer Affairs Agency's website.

Content required to be indicated by law

Of the substances to be removed listed in the following table, what and how much can be removed is to be specified. Of course, these are part of the "Specifications and Standards for Each Food" set forth by the Ministry of Health, Labor and Welfare.

Indicate for each term indicating the type of substance to be removed listed in the following table. Following the term, add in parentheses "total filtered water volume (in liters)," "80% removal rate," and "test results measured in accordance with JIS S3201 or Appendix A of the same standard" (the allowable range is within -10% of the indicated filtration flow rate).
Water Purifier | Consumer Office

Classification of substances to be removed Terminology indicating the type of substance to be removed (display name)
free residual chlorine free residual chlorine
Turbidity (substances that cause turbidity, such as suspended particulates in water) impurity
volatile organic compound chloroform
total trihalomethane
agrochemical 2-Chloro-4,6-bis-ethylamino - 1,3,5 - triazine (CAT)
mould smell 2-Methylisoborneol (2-MIB)
heavy metals soluble lead
- anionic surfactant
- phenol
- geosmin


In addition to the above, the following items can be labeled if they meet the standards voluntarily set by the Water Purifier Association.

  • Iron (soluble)
  • Iron (particulate form)
  • soluble manganese
  • Aluminum (neutral)
  • Perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) (part of the organofluorine compounds (PFAS))
JWPASB(2023)Standards for products and performance of water purifiers


Therefore, we can determine the performance of a water purifier by examining which of the above standards set by the Consumer Affairs Agency (and those set by the Water Purifier Association) it meets and how many liters it is capable of filtering.

Product Comparison Chart

Now I would like to compare the above points. The products are compared to the highest-performing products as of April 8, 2023, which are directly connected to the faucet.(Only Brita did not have a water purifier directly connected to the faucet, so we have listed the specs for the pot-type water purifiers.)

Company Name

Brita Toray Industries, Inc.
brand name - trevino
model number 1045056 MK207SLX
free residual chlorine None stated ○(1500L)
impurity None stated ○(1500L)
・chloroform None stated ○(1500L)
・bromodichloromethane None stated ○(1500L)
・dibromochloromethane None stated ○(1500L)
・bromoform None stated ○(1500L)
・tetrachloroethylene None stated ○(1500L)
・trichloroethylene None stated ○(1500L)
・total trihalomethane None stated ○(1500L)
CAT None stated ○(1500L)
2-MIB None stated ○(1500L)
soluble lead None stated ○(1500L)
anionic surfactant None stated ○(1500L)
phenol None stated ○(1500L)
geosmin None stated ○(1500L)
Iron (soluble) None stated None stated
Iron (particulate form) None stated None stated
soluble manganese None stated None stated
Aluminum (neutral) None stated None stated
PFOS and PFOA None stated None stated
- 8,982 yen


Company Name

Mitsubishi Chemical Panasonic
brand name ClinSuite -
model number CSP901 TK-CJ23
free residual chlorine ○(900L) ○(2000L)
impurity ○(900L) ○(2000L)
・chloroform ○(900L) ○(2000L)
・bromodichloromethane ○(900L) ○(2000L)
・dibromochloromethane ○(900L) ○(2000L)
・bromoform ○(900L) ○(2000L)
・tetrachloroethylene ○(900L) ○(2000L)
・trichloroethylene ○(900L) ○(2000L)
・total trihalomethane ○(900L) ○(2000L)
CAT ○(900L) ○(2000L)
2-MIB ○(900L) ○(2000L)
soluble lead ○(900L) ○(2000L)
anionic surfactant ○(900L) ○(2000L)
phenol ○(900L) ○(2000L)
geosmin ○(900L) ○(2000L)
Iron (soluble) None stated None stated
Iron (particulate form)
soluble manganese None stated None stated
Aluminum (neutral)
PFOS and PFOA ○(2000L)
6,027 yen 10,313 yen

Note 1, In this table, turbidity refers to substances that cause turbidity, such as suspended particulates in water.
Note 2, The figure in parentheses to the right of the circle is the filtration volume of water that can be filtered.
Note 3, Substances with "・" at the beginning are volatile organic compounds.
Note 4, prices are from Amazon on July 23, 2023.


First, let me explain about Brita. I thought Brita was good because I saw a lot of advertisements for it, but I found it to be unreliable.

There is an explanatory page on the website about the MAXTRA water purification cartridge for potable water purifiers, which explains the number of substances removed as follows

Main removed substances: chlorine, impurities such as lead and copper, herbicides, pesticides and pharmaceuticals**.
Reduction of certain trace impurities such as herbicides, pesticides and pharmaceuticals**.
Reduction of chlorine, volatile organic compounds, and odor sources***.
**If contained in tap water; tested by QFT Laboratories in accordance with NSF / ANSI 401
***Test results measured according to JIS S 3201
Brita Maxtra Plus Pure Performance Cartridges | BRITA®.


First, we verify whether it is true that chlorine, volatile organic compounds, and odor sources were reduced as a result of measurements based on JIS S 3201. To quote once more, the contents of JIS S 3201 are as follows

Indicate for each term that indicates the type of substance to be removed listed in the following table. The term should be followed by a statement in parentheses: "total filtered water volume (expressed in liters)," "removal rate of 80%," and "the fact that the test results were measured in accordance with JIS S3201 (Tolerance is within -10% of the indicated filtration flowrate.).


Did you notice that none of the required items were listed, nor was there a detailed description of the removed substances in the PDF product description?

I also looked up QFT Laboratory, but a search under the official name, QUALITY FILTER TESTING LABORATORY LLC, did not turn up any water purifiers approved by this agency. On the contrary, the street view that came up after searching the address on Google Maps is from October 2019, and there is a parking lot all around and no institute-like building at all. It is not even under construction.

Therefore, we do not trust Brita at all in this blog.


The next most distinctive is Panasonic. In addition to having the same number of substances removed as the Mitsubishi, it has a very high filtration rate. Panasonic explains that phenols, benzene, and carbon tetrachloride can also be removed, but we will ignore those because they must be legally removable.


Is the Panasonic water purifier really the best?

With the data so far, we can conclude that "Mitsubishi and Panasonic have the highest performance. Panasonic has the highest water purification capacity." However, there is a part that I personally cannot agree with.

That is, despite having so much technology, Panasonic has not built an industrial water purification facility. If it has more than twice the filtration volume, it should be able to beat Mitsubishi in the price competition.

Mitsubishi, on the other hand, makes large-scale water treatment facilities used in a variety of settings, as shown below. Hollow-fiber membranes are the material used for filtration, and smaller versions of these membranes are used in household water purifiers.

Water purification and wastewater treatment systems

Mitsubishi's various water treatment systems, including wastewater treatment systems based on the membrane bioreactor method and industrial water filtration systems based on hollow fiber membrane water purification technology, have earned high praise from companies and ministries.
Water Purification and Wastewater Treatment Systems | Product Information|Mitsubishi Chemical Corporation


Mitsubishi also makes "ultrapure water," a machine that purifies water with a very low amount of waste.
Ultrapure Water System|Products|Mitsubishi Chemical Aqua Solutions Corporation


As I said in my article on air purifiers, the smaller the filter gap, the more often the filter should be replaced. I am somewhat skeptical of Panasonic, which has an unusually high filtration rate despite its high performance.

For these reasons, this blog presents Mitsubishi as the most reliable manufacturer.



Once you have decided on a manufacturer, all you need to do is decide what shape of water purifier you want to buy.

The advantages and disadvantages of each shape and the recommended situations are shown below.


・Easy water purification

・That it takes time to purify water.
・Low water purification rate.

The advantage is that it is easily portable. It can be used to purify water from the tap on the terrace or in the garden, for leisurely drinking, or for feeding to dogs.


Directly connected to the faucet

This is the most widely distributed of the many water purifiers. It can be used in all types of kitchens, as it has parts that match the shape of the faucet.



・Directly connected to the faucet, so water purification is immediate with water pressure.

・none in particular

Products for the general public

This is the cheapest product among those with the highest number of substances removed. Still, they can be used without any inconvenience, as they can produce both straight and showers.  (The purified water is straight.)


Advanced Products

Compared to products for the general public, these products have evolved in the following ways

  • It has an LCD so you know when to replace the cartridges.
  • The amount of water poured is displayed on the LCD, eliminating the need for a measuring cup.
  • It can make water particles finer and reduce water splashing.


Replacement cardridges are common.


There used to be a stationary type, but it is more than gone.

Have you lost the impression that tap water is bad for your health? We hope that people no longer avoid tap water for no reason.