Johor data centres turn to recycled water

Currently, Ranhill SAJ runs 47 treatment plants capable of producing 2,352 million litres of water per day. Late last year, Johor announced they will no longer approve less-efficient Tier 1 and Tier 2 data centres. It also highly recommends the use of alternative water sources to cool data centres.

Furthermore, on July 16, the Dewan Rakyat was told that new data centres will only be approved if energy and water supplies are sufficient. Deputy Investment, Trade and Industry Minister Sim Tze Tzin also said that domestic consumers would remain the first priority for water supply.

In September 2025, SPAN published guidelines for data centres to use alternative sources of water. The guidelines prioritise using reclaimed water for cooling if it is available, or installing air-cooled systems with zero discharge.

“The issue of reclaimed water is something that’s important, given that most of our data centres are using potable drinking water for the cooling of their servers,” said Santiago.

The data centres in Johor are now building their own water treatment plants to siphon clean water into their facilities.

Two of them – BDC and ZData/Computility Technology – use water from Malaysia’s wastewater and sanitation company Indah Water Konsortium (IWK).

The BDC water treatment plant, using patented membrane-tech similar to NEWater, and reverse osmosis, opened in Ulu Tiram in August last year. The ZData/Computility Technology data centre’s water treatment plant opened in March 2026 in Gelang Patah. Both are connected to the same network of effluent water.

A third data centre, DayOne, is drawing and treating raw water from Sungai Tebrau for its facility in Kempas under an agreement with state government-owned company Johor Special Water (JSW), while a fourth data centre AirTrunk’s water treatment plant has not started operations.

How it works

Bernama recently went for a site visit at the BDC water treatment plant in Ulu Tiram, which prohibits recordings of the plant or technology used.

At this treatment plant, wastewater is funnelled from the IWK sewage treatment tank, located about six kilometres away. It goes through the equalisation tank, which, the BDC treatment plant manager told Bernama, is to ensure all incoming wastewater has the same standards, such as temperature, pH and oxygen levels.

Later, the wastewater goes through the anoxic tank, then the oxidation tank, before going through the membrane bioreactor, where the wastewater is refined and filtered several times before going through reverse osmosis.

The leftover waste produced during the refining and filtering process, called sludge, is funnelled into the sludge concentration tank, where staff analyse the content for disposal.

BDC uses the expertise of Suntar International, a Singaporean membrane technology company, to filter the water and reduce contaminants.

“The membrane bioreactor is a globally accepted system and is an upgrade to the conventional activated sludge system, which relies on gravity and time (and a large land footprint) to allow sludge to settle. This improves the water quality,” commented water engineer Datuk Nor Hisham Mohd Ghazali, former chairman of Malaysian Water Partnership, a non-governmental organisation. Nor Hisham is not involved with BDC.

In the reverse osmosis room, the treated water is clean enough for washing hands, which Bernama did, and to take a shower, which Bernama did not. The BDC manager said the water, however, is not for drinking, adding that he would not risk it even if it is boiled.

After reverse osmosis, the water flows into a permeate tank before being piped to the data centre. After use, the water – which is still clean – is flushed into the river. (Sections 21, 24, 25 and 51 of the Environmental Quality Act 1974 require any industrial water discharged into rivers to meet certain quality standards and the temperature to be under 40 degrees Celsius to ensure the health of the river and aquatic life.)

In an email response to Bernama, BDC said before discharging the water into the river, “the water is cooled through the cooling tower process itself” and released at room temperature”.

“An online water quality monitoring device is installed at the equipment discharge outlet to ensure the water quality remains within discharge standards at all times,” it added.

Possible risks

Data centres in Malaysia are not the first to use reclaimed water to cool their system. While this method is more sustainable, it has not always been smooth sailing.

In January this year, a data centre attached to Meta introduced a rare bacterium to the sewage discharge in Cheyenne, Wyoming, in the United States, when the centre flushed its water system. Nor Hisham acknowledged that a similar incident could happen in Malaysia.

“Bacteria are all around us … It can happen in Malaysia, so you need protocols for DOE (Department of Environment) testing of data centre water cooling systems to reduce that risk,” said Nor Hisham, adding that current guidelines on effluents discharged into rivers are applicable to all industries and not specific to data centres.

In its email to Bernama, BDC said its staff conducts routine water sampling tests to confirm that the water being released into the river meets local environmental laws and guidelines.

As for ZData, it said in a statement to Bernama that they operate an “in-house water quality laboratory that conducts regular testing of discharged water”.

The wastewater from IWK is only for BDC’s Ulu Tiram site, as its data centre in Sedenak Tech Park has a freshwater source, according to BDC staff. According to a news report by Water and Waste Water Asia [https://waterwastewaterasia.com/higher-costs-tighter-rules-johors-data-centres-turn-to-reclaimed-water/], BDC’s water treatment plant currently processes five million litres daily, with plans to expand to 20 million litres as demand grows.

Bernama also visited the Computility Technology data centre in Gelang Patah, which uses a more conventional water treatment method by Ocned Water Technology.

Computility Technology director Yeo Yong Hwang told Bernama that they were planning to have four water treatment plants. The current treatment plant processes four million litres of water per day for the data center.

He added that using reclaimed water was part of the company’s green goals.

“We don’t need to compete with each other to use the potable water,” he said. “We use 100% reclaimed water.”

No longer worried about water, Ramli now hopes that local residents will be given priority for job opportunities.

“I’ve talked to him (Yeo). I told him, ‘If possible, Mr Yeo, short-term or long-term, please consider giving a chance to our youths here’,” he said. – Bernama