An independent laboratory investigation has found hazardous industrial substances in the bright green liquid that leaked from the Chinese-owned CATL battery plant in Debrecen earlier this month, contradicting earlier claims by the company that the incident involved harmless coloured water.

Weird green liquid leaked from the CATL battery plant in Debrecen

The alarming incident took place on 5 May outside Gate 2 of the factory, where green liquid bubbled up from a drainage system and flowed onto the road. Videos of the incident quickly spread online, prompting concern among local residents and environmental groups. At the time, CATL stated that the liquid came from a pressure test during which water coloured with food dye had been used to identify possible leaks in the plant’s pipe system.

According to the company, the water posed no environmental risk and surfaced only because of a blockage in the drainage network. However, a sample collected by the environmental organisation Mothers of Mikepércs for the Environment and analysed by an independent laboratory paints a different picture, reports 444.

Battery-production chemicals detected

The laboratory reportedly detected several substances commonly associated with lithium-ion battery manufacturing, including manganese, lithium, nickel, cobalt and NMP (N-methyl-2-pyrrolidone), a toxic solvent used in battery production. NMP is considered particularly dangerous because of its harmful effects on unborn children and should not enter public drainage systems under any circumstances.

According to the test results, the liquid that leaked from the battery plant had manganese levels at 160 micrograms per litre, more than three times Hungary’s drinking water health limit of 50 micrograms per litre and roughly fifteen times higher than typical levels found in tap water. The environmental group said the composition of the sample closely matches the raw materials used in NMC-type lithium-ion batteries, which contain nickel, manganese and cobalt.

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Authorities call for transparency

The organisation argues that the findings indicate a physical connection or leakage between the factory’s supposedly closed internal technological system and the external rainwater drainage network. “This toxic industrial cocktail containing heavy metals and solvent escaped uncontrollably into the open ditch outside the factory, posing a direct environmental threat,” the group said in a statement.

The group also noted that official authorities carried out their own sampling on the day of the incident and called on the government to release the results publicly. Enikő Tompa, an MP representing the Hajdú-Bihar region, has also demanded immediate clarification from the county government office and urged officials to publish the findings of the official investigation without delay.

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