The Land, Infrastructure and Transport Ministry has informally decided to pursue new legislation to prevent urban disasters caused by sewerage systems overflowing during heavy rain, according to ministry officials.

The planned legislation is aimed at dealing with the increasing incidence of torrential rainfall in urban areas that some meteorologists are blaming on global warming, and at improving water circulation, the officials said.

In September 2000, more than 7,000 homes in and around Nagoya were flooded after a levee broke during record rainfall.

The ministry plans to submit a bill to the Diet after it opens next year's regular session in January that would call for well-considered river, reservoir and sewerage system controls, including sewage treatment facilities, to reduce storm-induced disasters.

The bill would require the national government and prefectures to designate rivers and areas likely to suffer from urban water disasters with a view to devising prevention plans.

The plans would specify the amount of water sewerage systems can channel into rivers, and the amount they should retain at their facilities when high river levels prevent them from discharging water.

They would also specify the amount of water to be kept in reservoirs and to be allowed to seep into the ground, the officials said.

The ministry intends to use tax breaks and land purchases to induce condominium and land owners to build reservoirs and other facilities in condo basements and on unused land, the officials added.

The ministry would consider adding a mechanism in which the government would buy existing reservoirs by regarding them as part of river systems. It would also study the possibility of the national government teaming up with municipalities to preserve reservoirs.

To drain rainwater efficiently, centralized management of water for river systems would be pursued, for example, by enabling a river manager -- not a sewerage system manager -- to use pumps at sewerage facilities.

To curtail the ill effects of projects that would reduce the function of natural reservoirs, the ministry wants prefectures to be allowed to issue permits to developers for the building of reservoirs.

Some observers say the legislation is a way for the ministry to secure its budget. This is because the ministry is under pressure to cut spending on sewer projects now that such systems cover 62 percent of the overall population.

Combined with the spreading use of digestion tanks and other water treatment facilities in remote areas, sewerage projects have little room for further growth, they say.

In the nation's three major metropolitan areas, 80 percent of water disasters are caused by rainwater not yet drained into rivers.

The government has established water management programs since 1980, aiming at rivers and areas around them in city areas. But such programs have not been fully implemented because they are not mandatory.