More than half of the country's sewerage works are performing poorly or are in a "critical state".

This was revealed yesterday when the Department of Water and Environmental Affairs released its 2011 Green Drop Report in Cape Town.

The report details an assessment of municipal waste water management systems, and credits well-run systems with a Green Drop Award for "excellence in achievement".

Six provinces received a Green Drop Award, with the Western Cape leading the pack with 19 awards.

A total of 156 municipalities and 821 waste systems were assessed - in 2009 only 98 municipalities and 444 systems were assessed.

Of the 821, 40 were found to be in excellent condition, 78 were in good condition, 243 were average, and 143 performed very poorly.

It said 317 plants are in critical condition.

The picture in Eastern Cape was grim: 64% of the province's sewerage works posedhealth and environmental risks.

"Renewed efforts must be dedicated to compel plants into medium and low-risk positions," the report said.

None of the water-treatment plants in Limpopo won an award, indicating that the performance of the entire province was weak.

At the province's Leyenye works, the report said, "Poor effluent quality is being discharged as a result of inadequate treatment during upgrading of the plant, presenting a significant risk to public health and the environment, given that the receiving resource is the sensitive Letaba River, which flows into the Kruger National Park."

Minister of Water and Environmental Affairs Edna Molewa, who presented the report, said the situation was unacceptable.

"I am concerned ... that we still have, especially given the disparities of our provinces and our municipalities, a situation where some of the municipalities are still struggling to get their level of accounting on the quality of water to the extent as it is reflected in Eastern Cape, as well as in Limpopo and poorer provinces."

She said monitoring of water-treatment systems in Eastern Cape and Limpopo would be prioritised because of the high risk they posed.

The minister also unveiled the 2011 Blue Drop Report - which looks at drinking water quality and management.

A total of 66 systems won Blue Drop Awards during the 2010-2011 assessment period for excellent compliance and standards, and for "good management practice in drinking water quality management", among other criteria.

The top five performers were Johannesburg, Cape Town, Ekurhuleni, Witzenberg local municipality and West Coast district municipality.