Action must be taken against the "arrogant" management of the eThekwini municipality, Cosatu said on Monday.
The union in KwaZulu-Natal planned to engage with the South African Municipal Workers' Union (Samwu) to consider the stalemate between the municipality and its workers.
In a statement, Cosatu provincial secretary Edwin Mkhize said the situation was worsening because the city's management showed an "I don't care attitude" towards workers.
"The situation in eThekwini municipality is worrisome and becoming more disastrous. Most distressing is the failure by the municipality, as an employer, to be innovative in resolving the stalemate. But this is not shocking to us because it displays the very barrenness the municipality has showed in handling the matter in question leading to this havoc," he said.
Parts of Durban have been without water for at least a week after workers employed by the city's waste and sanitation department went on a strike over discrepancies between their salaries and the pay of those employed from the ANC's former military wing.
The workers are demanding to be elevated to grade 10 salary level, which they claimed the Umkhonto weSizwe Military Veterans' Association workers were receiving.
According to the workers, the MK veterans, who were employed by the city in 2016, were upgraded from grade 4.