The SA Municipal Workers Union (Samwu) and its allies were preparing to strike after wage negotiations between them and their employer body failed, the union said on Friday.

The union was waiting for completion of the processes that make the strike legal after negotiations failed on Thursday, spokesperson Tahir Sema said.

Smaller unions, the United Association of South Africa and the National Education, Health and Allied Workers' Union could also be taking part in the strike, depending on whether their workers accept the employer's offer, they said.

Employer body the SA Association of Water Utilities (Saawu) refused the unions' request of a 13.5% increase for the lowest paid workers and an 11% increase for the highest paid workers.

Its last offer was a 9% increase, across the board.

Sema said a strike could leave many consumers without water.

Wage negotiations were taking place under the auspices of the Amanzi Statutory Council, which covered 6 000 workers in the water provision sector.

Through the council, big water boards like Rand Water and Umgeni Water were brought together with smaller water boards like Overberg in the southern Cape, and Namakwa in the Northern Cape.

Samwu would be having further discussions with affected communities and other public sector unions who were considering their own industrial action in support of their wage demands.

  - Sapa