VOL.4

Vol.4

Is tap water safe to drink?

Answering my question, Dr. Sadao Kojima, whose work as Director of the Tamagawa Water Purification Administration Office involves him in the investigation of water treatments and the purification of river waters, replied, "Yes, it's safe although, strictly speaking, I can't say that it is 100 per cent safe".

In the past, human waste was put to use on farms as a fertilizer and since the accompanying polluted water was not discharged directly into rivers, water taken from the latter was relatively safe and pleasant to drink. Our custom of drinking un-boiled water without a second thought can be attributed to this water circulation cycle of earlier times.

However, one result of the period of high economic growth in the 1970s was that chemical fertilizers supplanted the use of human waste. At the same time, the growth of urban populations dramatically increased not only the demand for water but also the extent of water contamination. Because existing water treatment facilities were unable to satisfy the growing demand, a rapid sand filtration method developed in America was introduced.

Two advantages of this rapid sand filtration method, which employs large quantities of chemicals to purify dirty or turbid water, are that it uses less land and needs less manpower.

However, although it can remove almost 100 percent of the granular contaminants, it cannot remove dissolved contaminants. Because the water passes rapidly through the sand layer (a bed of granular media), dissolved organic material cannot be removed, so that the filtered water retains a small amount of bacteria. It is for this reason that disinfection by means of chlorination is necessary to ensure supplies of safe drinking water.

In the rapid sand filtering method, chlorine should be added both before and after filtration. The purpose of post-filtration chlorination is to reduce the risk of possible contamination before the water becomes available for human consumption. However, the chlorine may react with ammonia contained in the water to form trichloroamine, which gives off an odor of chlorine.

The chlorine used prior to filtration reacts with humic substances ? organic matter which is not decomposed by the action of waterborne micro-organisms ? to generate trihalomethane, which is carcinogenic. The presence of trihalomethane is not a potential cause of imminent danger, as the current level of content in tap water is far lower than the established maximum permissible figure of 1 mg/L. Even so, it is better if the substance can be completely removed. More and more water treatment plants in Tokyo and in Saitama Prefecture are therefore using advanced but extremely expensive water purification systems which employ ozone and particulate active charcoal to remove the trihalomethane.

Then there is the problem of chemicals. We are now presented with the dilemma of choosing between safe water and the convenience offered by increasing the use of chemicals. The bio-concentration of such chemicals permits them ultimately to enter the human body via the food chain, and this process presents a greater risk than that arising from substances contained in water.

In the sea, chemicals which do not dissolve readily in water, such as DDT or PCB, accumulate in plant plankton, which are eaten by animal plankton and are bio-concentrated tenfold. They are further bio-concentrated a hundredfold in small fish and are concentrated still further in larger fish.

Ultimately, they are bio-concentrated several thousands times in the fish that we eat. Organic mercury (methylmercury chloride) which had bio-accumulated in fish caused Minamata Disease, leading to the poisoning and death of people who ate them. It is known that dioxin can also be ingested through fish.

Tap water contains very few harmful substances and, moreover, the average daily intake of water is only 2.5 liters. The quantity of harmful substances entering our bodies from water is almost nothing compared with the amounts that we absorb from our food and from the air that we breathe.

Interview with the Tiber River Basin Authority

In Italy, the concept of water as a public amenity, regulated through a system of public water administration, has been protected by law since the promulgation of a Regio Decreto in December 1933. Law 183/1989 established the integration of water and soil management and set up River Basin Authorities, each of which manages one of six national river basins (the Po, Tiber, Arno, Liri Garigliano & Volturno, Isonzo, Piave, Taliamento & Brenta, and Adige basins). The most important of these are the Po and Tiber river basins. In particular, the River Tiber, which flows through six states, including Rome, is under the jurisdiction of the River Tiber Basin Authority, which takes the leading role by representing Italy when the relevant EU directives are established.

The Authority has an Institutional Committee and a Technology Committee. The former comprises representatives of the Ministries of Environment and Land Protection, Infrastructure, Culture, Agriculture and Forestry, Civil Protection (a voluntary civil organization) the Cabinet and the Governors of States in the Basin. They discuss and establish various plans and regulations relating to the Tiber, its tributaries and its basins, and these are then applied nationwide as Presidential Decrees.

The Technology Committee is an advisory body offering consulting services for use in implementing the plans. It consists of a Chairman and 24 members, 12 from the Ministries and 12 from the States.

The purpose of Law 36/1994 (the "Galli" Law), which is based on Law 183, was to deal with the consolidation of water services into larger management units. It delegates authority to regions and municipalities. Legislative Decree 152/1999 defines a new Italian water quality infrastructure and unifies all the norms for the implementation of European Council directives.

Water-related matters of mutual interest to Optimal Management Units or ATOs (inter-municipal agencies) are co-ordinated as specified by the Galli Law, and those of inter-state relevance are co-ordinated by the Basin Authorities.

Report on the 1993 Minuma paddy Field Harvest

It was the idea of "more paddy fields in Minuma" which fired our imagination and led us, in the Spring of 1993, to start cultivating an area of farming wasteland, on which we could grow rice. In May, the new field was supplied with water from the Tone River, but our amateur paddy field would not retain it. However, thanks to the help of the Kubota Corporation, an agricultural machinery manufacturer, we finally managed to keep the water in the field, and successfully planted our first rice on June 5. Water continued to leak away after the planting and large holes dug by moles exacerbated the problem. However, the leakage stopped eventually and the rice plants began to grow. But then the paddy field was devastated by an unusually cool summer. The rice plants in some parts of our field were damaged by rice blast fungus as well as by harmful insects. Millet (barnyard grass) also began to grow. We reaped it manually, so as to avoid the use of weed killer. On August 20, well behind schedule, an ear of rice finally appeared, followed by a small white flower and solid grains... the rice. To protect the rice from sparrows, we struggled to place a net around the field. Under our watchful eyes, the ears of rice became larger and heavier in September. The first harvest day of the new Tamenaga Paddy Field finally dawned on October 12.

The yield was 336 kg per 10 are... not bad, considering the cool summer. And, of course, there was another great harvest... cultivating the wasteland provided a home for plants and other forms of life. The harvested rice was shared among our nembers, with 60 kg going to the owner of the land.