Selangor often faces sudden water cuts as a result of river contamination.
Rivers are an important water source to millions of households in the state and when these waterways are contaminated with toxic pollutants, nearby water treatment plants are forced to close until the contamination is cleared.
This disrupts water supply to households in Petaling, Hulu Langat, Kuala Langat and Sepang districts for days with notice issued often at the last minute.
The rivers that are most commonly polluted are Sungai Semenyih and Sungai Selangor.
One of the worst incidents was in 2013, when an illegal factory in Rawang was reported to be responsible for an oil pollution in Sungai Selangor.
Oil from the factory was dumped into one of Sungai Gong’s tributaries which flows into Sungai Selangor, leading to the forced closure of four treatment plants which produces 2.67 billion litres of water daily.
The water cut affected over one million users in Petaling Jaya, Kuala Lumpur, Klang, Shah Alam, Gombak, Hulu Selangor, Kuala Langat and Kuala Selangor.
In 2014, rivers were repeatedly polluted, causing treatment plants in the state to shut down 42 times, affecting consumers for about 2,838 hours in total.
Water treatment plants in Sungai Semenyih and Bukit Tampoi were also shut down about six times last year as a result of contamination.
One of the incidents was when Sungai Semenyih was contaminated with ammonia and manganese.
As a result of this, water supply to almost 400,000 households were cut without notice.
Recently, water treatment plants near Sungai Semenyih had to be shut down twice in the span of two weeks, because of odour pollution, affecting over 330,000 households.
This was followed by dry taps at 420,000 households in Kuala Lumpur, Petaling and Hulu Langat after the abrupt halt of operations at the Langat and Sungai Cheras Batu 11 water treatment plants as a result of odour pollution in Sungai Semantan, Pahang.