Singapore has been supplying an additional 6 million gallons per day (mgd) of potable water to Johor since Saturday in response to a request for assistance by its water regulatory body, Badan Kawalselia Air Johor (Bakaj).

The month-long arrangement is due to dry weather which has severely affected water levels in Johor's Sungai Layang dam, and will not affect the water supply in Singapore in the short term, national water agency PUB said yesterday.

Dry conditions have also brought water levels in the Linggiu Reservoir to a historic low of 33 per cent, down from 40 per cent in April, PUB said.

The PUB-operated reservoir improves the yield of water from the Johor River, which helps to meet half of Singapore's water needs. The Republic draws up to 250mgd of raw water from the river, and supplies Johor with treated water in return.

The temporary increase, which is being supplied by the PUB-operated Johor River Waterworks, brings Singapore's supply of treated water to its closest neighbour to 22mgd.

From last August to January this year, PUB supplied an additional 5mgd to 6mgd of potable water to Johor under an arrangement similar to the present one.

Professor Asit Biswas, founder of the Third World Centre for Water Management, does not foresee any problems for Singapore with such an arrangement over the short to medium term.

But the distinguished visiting professor at the Lee Kuan Yew School of Public Policy at the National University of Singapore cautioned that Singapore's per capita daily consumption of 150 litres is "far too high".

He said water conservation efforts in Singapore and Johor can be improved through economic, social and other changes.