Waste water treatment services across the country "are far from acceptable" and "must be addressed as a matter of urgency", a department of water affairs report has revealed.

The Green Drop Report, a performance audit of the country's sewage plants, also reveals that of the 449 plants assessed, only 7% complied with national and international standards.

Releasing the report in Pretoria yesterday, Water Affairs Minister Buyelwa Sonjica said she was unhappy with the state of sewage plants across the country.

"I want to state clearly that we acknowledge the shortcomings in the management of waste water treatment works as revealed by this report. These assessments were done in order to help struggling local authorities to better manage their treatment works and to incentivise those who have done well," she said.

"Yes, the findings of the inaugural Green Drop Report are certainly not favorable, but all is not lost. The report confirms the need for improvement of waste water services, and requires pioneering initiatives that would result in sustainable turnaround."

Dr Mark Graham, a water scientist who has extensively tested pollution in South African rivers, said the Green Drop report and the state of the country's sewage systems was "critical".

He said the management of sewage was "intermediately linked" to the quality of the country's drinking water and that unless the situation was remedied, drinking water quality would ultimately be affected.

"Sewage effluent goes into the rivers and eventually the dams. Most dams receive the nutrients in excess and it ends up causing problems in the dam and effectively in the long run it can affect the quality of drinking water," he said.

"Excess nutrients feed the blue-green algae which can majorly effect drinking water because of the toxins it releases."

The report reveals that of the 449 treatment plants assessed, 7% were classified as excellently managed, and 38% scored between 50% and 89% when measured against the set criteria.

According to the report, only 449 of the 852 municipalities in the country were assessed because many did not "adhere to the call" for assessment, weren't "sufficiently confident" to be tested, or were unable to provide enough information.

Only 45% of the plants assessed scored above 50%.

One of the plants not assessed was that of the Madibeng Municipality in North West. Raw sewage is flowing into the Hartbeesport Dam, which falls under the municipality's jurisdiction.

The municipality's water and sanitation head, Lerato Sabidi, said the department "knows why we could not comply".

"They are aware of our challenges and we are currently attending workshops and in discussion with them about how we can improve the situation."

Rick van Rossum, a member of the Hartbeesport Water Action Group said: "Madibeng just can't cope, the department has appointed new administration, the mayor and the mayoral committee have been suspended, and municipal workers are constantly on strike."

Sonjica said yesterday the finding that 45% of the country's sewage plants performed within acceptable standards "implies that in spite of all the evident shortcomings, the sector is not in complete disrepair".

"I am, however, concerned about the remaining 55% of the assessed waste water treatment works that scored below 50%."

She said legal action against errant municipalities was one possible strategy her department could employ to address the problem.