Nepal will begin studying ways to improve its water supply in September with the help of a technical assistance grant from the Asian Development Bank.

At present, there are no public water supply systems for any of the small rural communities. Mountain villagers get water from springs and streams, while villagers in the Terai lowland area depend on ponds and well water. Most of these people also have poor sanitation facilities that further contaminate their water supply.

Water-borne and water-related diseases are common throughout Nepal.

Under the technical assistance grant, a team of consultants will study 100 small rural communities and 14 towns with populations of more than 10,000. The team will devise a project to provide safe water to the villages and towns, after taking into account the cost and feasibility of installing a safe water supply system in each community.

The consultants will also review the success of an ongoing ADB financed rural water supply project that was approved in December 1984.

The bank has also granted its first equity investment and direct loan to a private enterprise in India.

DCL Polyesters Ltd. of Mahararashtra State last month received a $3 million equity investment and two loans totaling $21 million from ADB to start a polyester yarn factory. The factory will produce yarn that will be used by power loom operators and textile mills to make clothing fabrics. A small part of the yarns will be sold to home weavers and knitters.

There are 12 polyester yarn manufacturers in India. They produced about 67,000 tons of yarn in 1985-86. DCL's factory is expected to add 15,000 tons to that total. According to government policy, levies and duties on synthetic fibers will be progressively reduced to make synthetic and blended fabrics affordable to the average person.

ADB's assistance is 21 percent of the project's cost. Other contributors include Deccan Cement Ltd., an Indian cement producer; the State Industrial and Investment Corp. of Mahararashtra Ltd.; and the Swiss firm of EMS-Inventa AG.