Just when you thought it was safe . . .

The water from your tap may not be as clean as you think


If you live in an old apartment or condominium complex of fewer than 10 units, you might want to check the tap water. Pour some into a clear glass and take a whiff. Does it smell of chlorine? If it does, you don’t have too much to worry about. It might not taste good, but at least the chemical smell indicates it’s bacteria-free. But if it smells of something else, such as mold or ammonia, or if it’s cloudy or has particles floating in it, you’d rightly be suspicious of its quality.

So then what should you do? Call the local waterworks bureau? Perhaps, as these bodies are responsible for problems regarding water supply. However, if the cause of the problem is your housing facility’s water tank, you’re wasting your time calling municipal authorities, as in such cases responsibility rests with the owner of the building.

Unlike in one- or two-story houses, where tap water comes directly from the distribution pipes, in most buildings three or more stories high, water is temporarily stored in water tanks. This is because the pressure from the distribution pipes isn’t sufficient to boost the supply up to the higher floors directly.

These water tanks are, however, not always in a sanitary condition and are often the cause of problems. If they are not maintained properly, mold and algae can grow inside them; sometimes, even dead cockroaches and rodents are found floating there.

If you are concerned about the quality of your water, your neighborhood public health center will be happy to test a sample if you take one along. The fee for this service varies from place to place, though as an example, the center in Tokyo’s Minato Ward charges 6,700 yen.

Although that may seem a bit expensive, as a Minato Ward public health department spokesman said: “If it turns out you do have something wrong with your tap water, we send a professional to your place and deal with the problem for free.”

Although there is a law that obliges building owners to clean the water tank annually, it does not apply to tanks smaller than 10 cu. meters, like those usually found at smaller housing facilities.

The Japan Building Water Maintenance Association estimates that there are some 650,000 unregulated water tanks around the country, and its director, Kazuyuki Tasaki, says he suspects that more than 60 percent have not been cleaned for years.

“Some owners proudly say they regularly clean the tanks, but many of them mean every three or four years at best and not every year,” says Tasaki. “When the owners are not living in the same buildings, they tend to be indifferent to this type of maintenance.”

Tasaki warns that residents of decades-old buildings should pay especially close attention to the quality of water coming out of their taps. This is because until the late 1960s, most water tanks were made of iron, and many aging buildings are still equipped with these relics which have a tendency to rust and turn the water red. Sometimes, they completely rust through, forming cracks in the tank walls that allow dust, rainwater and even small animals to get inside.

To avoid such problems, iron tanks were gradually replaced by plastic varieties. However, the early plastic tanks were often translucent, so allowing algae to grow. Algae can prosper in water exposed to light of only 100 luxes, which is equivalent to the brightness of a six-tatami-mat room lit by a 60-watt bulb.

Tasaki says some cyanobacteria (blue-green algae) produce a toxic substance called Microsystis that progressively damages most organs, including the liver. Today plastic water tanks that do not transmit light are standard, but the old tanks are still in use in many older buildings.

Fortunately, the law concerning the cleaning of water tanks was revised last month, and as of next April all water tanks for residential buildings will have to be cleaned once a year.

Meanwhile, many waterworks authorities nationwide have been working to fit new buildings with a direct-connection, boosted-pressure water supply. In this way water can be supplied to buildings 10 stories and higher directly from the water distribution pipes, with no need for a water tank. The Tokyo Metropolitan Waterworks Bureau, for one, introduced this method in 1995, and 11,692 buildings had adopted it by the end of May this year.

“Even old buildings can make the switch from a water tank to the direct-connection water supply if they meet certain requirements,” says Hideaki Haraguchi of the Tokyo bureau.

Although these systems are more sanitary, they are not recommended for certain institutions such as hospitals, hotels and schools. “If electricity were cut off for some reason, the water supply would also be stopped right away, and this might cause big problems at such places,” explains Haraguchi.

Tasaki also emphasizes an important role water tanks still play, especially in big cities like Tokyo. “We cannot live without water,” he says. “If you have a water tank, you will still have water for a little while even if a big earthquake hits your city and utilities are cut off.”