In a bid to prevent water pollution in rivers caused by chemical substances, the Environment Ministry will start a survey on the management of liquid waste from factories owned by chemical and other manufacturers at about 2,000 locations across the country.
The ministry also will discuss the possibility of increasing the number of places covered by the Water Pollution Prevention Law, which monitors river water at 235 locations in the country and controls hazardous substances in industrial waste liquid.
Four substances will be targeted in the survey, including hexamethylenetetramine (HMT), which is used in the manufacture of resin and synthetic rubber. The ministry will check the amount of factory discharge and what kind of chemical substances exist in the water in question, and in some cases analyse the components.
HMT reacts with chlorine to produce formaldehyde, which is controlled under the water quality standard for tap water. In May last year, waste liquid containing high levels of HMT produced formaldehyde exceeding the government-set standard at water purification facilities drawing water from the Tonegawa river system. This led to the suspension of water intake at six purification facilities in Tokyo and four other prefectures.
In addition to HMT, there are apparently 16 substances that produce hazardous byproducts by reacting with chlorine. However, the law does not cover these substances because they are thought to be low in toxicity. The ministry said it will decide whether these substances also need to be controlled after analysing the results of the survey.