National water agency PUB has, at Johor's request, supplied additional treated water to Malaysia after production there was disrupted due to pollution.

In response to media queries, PUB said yesterday that an additional six million gallons per day (mgd) of treated water was supplied between Jan 2 and Jan 4.

PUB said production at Johor's water plants was disrupted recently by pollution in the river catchment. PUB's Johor River Waterworks was not affected by the incident.

"At Johor's request, PUB helped to tide Johor residents over the water supply disruption by turning on PUB's Pasir Gudang offtake and supplying an additional six million gallons per day of treated water between Jan 2 and Jan 4, 2019," a spokesman said.

The 6 mgd was on top of the 16 mgd that Singapore usually supplies Johor.

Under the 1962 Water Agreement, Singapore is required to supply Johor with 5 mgd of treated water.

In practice, the Republic has been supplying 16 mgd of treated water to Johor at its request.

Last year, Singapore also supplied additional water in excess of the usual 16 mgd for 20 days at the request of Johor, PUB said.

PUB added that it has supplied all the additional treated water above 5 mgd on "a goodwill basis" at the same price as under the 1962 Water Agreement, that is, 50 sen per 1,000 gallons.

This is a fraction of the cost of treating the water, and "has been done without prejudice to our rights under the 1962 Water Agreement".

The agency said there has been longstanding cooperation between the water agencies of the two countries.

"PUB has thus far been responsive in assisting Johor residents to reduce the impact of their water disruptions, in the spirit of good neighbourliness."

According to recent reports in Malaysian daily The Star, a sand-mining company caused river pollution which disrupted water treatment at the Semangar plant in Johor on Jan 1.

The disruption affected 3,000 houses in Taman Desa Tebrau and surrounding areas.

Water was restored after more than 30 hours of the taps running dry.