Water level in Sungai Selangor's dam is reaching critical point due to the  prolonged heat wave and lack of rain, The Star Online reports.

Quoting data from the Selangor Water Management Authority (Luas) website, the news portal said the state's largest dam recorded a mere 40.53 percent capacity as of 8am today.

This is compared with 40.99 percent at the same time yesterday.

Unofficially, sources told The Star Online that water levels at dams would be deemed critical if they were below 40 percent.

However, Luas director Md Khairi Selamat disagreed with this figure, saying that the dam's critical capacity level would be at 30 percent.

"If it continues like this, that is if it doesn't rain at all, we have about 30 days before it (the Sungai Selangor dam) reaches the critical level," he is quoted as saying.

Water levels were also lower than usual at other dams:  Batu (90.72 percent), Langat (61.53 percent), Semenyih (77.49 percent), Sungai Tinggi (71.22 percent) and Tasik Subang (91.63 percent).

More than 60 percent of the Klang Valley and Selangor's 7.1 million users are supplied with water from the Sungai Selangor dam.

Selangor's depleting water resources have led the state to implement water rationing measures in a number of areas for the whole of March.