Sumitomo Corp. will double the head count of its global water division within seven years in a bid to boost the size of its water assets eightfold through investment and acquisitions.

Japan's third-biggest trading house plans to hire and transfer internally to expand the number of staff in the water utilities investment team to at least 30 from about 15 currently, Hideki Yamano, general manager of the wind power and water infrastructure department, said Tuesday.

Sumitomo plans to boost the number of people it hopes to provide water-supply services for, including sewage treatment, to 20 million from 2.5 million.

Sumitomo, Mitsubishi Corp. and Marubeni Corp. are accelerating buyouts of water-services companies outside Japan in a race with larger global rivals led by Veolia Environnement SA and Suez Environnement Co. of France.

China, India, Southeast Asia and the Middle East are being targeted by the Japanese and French companies for expansion.

"China and India are the two strategic points for our expansion of water services, mainly of sewage treatment, in Asia and the Middle East," Yamano, 50, said. "Making a cluster with good companies is the key for us to win a heated-up race with the global water majors."

Sumitomo announced last month it had signed an alliance deal with VA Tech Wabag Ltd. of India in a bid to tap growing demand for water supply and sewage treatment in the South Asian nation.

Sumitomo and VA Tech want to cooperate in developing startup water projects in the Middle East, North Africa and Southeast Asia, and in acquiring water treatment firms in the regions, Yamano said.