MANILA, Philippines - Authorities this month began reducing the supply of drinking water from dry spell-hit Angat dam, Metro Manila’s main source, prompting a utility to warn of service disruptions.

A weather bureau official said the water level at the multipurpose facility could hit a critical point as early as next week, forcing authorities to stop releasing supply for power and irrigation purposes.

Jorge M. Estioko, chief water resources development officer of the National Water Resources Board (NWRB), said the domestic water allocation from Angat dam was cut to 36 cubic meters per second (cms) this month from 38 cms in March.

Directly affected by the supply cuts were concessionaires Maynilad Water Services, Inc. and Manila Water Co., Inc. Maynilad, which services the west zone, will be getting 2,150 million liters per day (MLD), down from 2,400 MLD, while Manila Water will get 1,300 MLD from 1,600 MLD.

The normal water supply of 4,000 MLD from Angat is split 60-40 in favor of Maynilad.

Nathaniel A. Cruz, spokesman of the Philippine Atmospheric, Geophysical and Astronomical Services Administration, said Angat’s water elevation was 181.06 meters above sea level as of yesterday, way below the normal 190 meters and nearing the critical 180-meter level.

Mr. Cruz said the 180-meter critical level could be hit next week.

"Power generation cannot function if it reaches the critical level and the irrigation requirements of the farmers in Bulacan will also not be met. Domestic water use will be the sole function if it reaches that point," he said.

"Baka mas maging (It may become more) severe as expected so we have to monitor if it will decrease further. We expect rains to come pa (only) in the middle of June," Mr. Cruz said.

The NWRB’s Mr. Estioko, however, said they saw no need to revise planned water allocation cuts.

"We have not seen anything yet which will force us to revise set reductions," he said. "Our forecasts are being met ... so the allocation will remain as planned."

Maynilad, in a statement, said the reduction in water allocation would mean reduced pressure and shortened supply in some areas.

"With the recent 250 MLD reduction and the historically high water consumption levels during summer, Maynilad is estimating 156 barangays or around 8% of customer base will experience the impact of the raw water supply cutback," the company said.

Vulnerable areas in its service area include North Caloocan, South Manila, Tondo, Novaliches, Fairview and Pasay, the company said.

To mitigate the effects of the dry season, Maynilad said it would optimize the use of pumping stations, reservoirs, and mini-boosters.

Manila Water, for its part, said its services had not been reduced by the supply cut.

"Although the NWRB has further cut back allocation ... starting April, we still manage to supply the water requirements of our customers," company president Rene Almendras said in a separate statement.

Manila Water has a water loss level of 16.4% while Maynilad, which has a larger customer base and an older pipe system, has a much higher 59%.