POORLY disinfected drinking water is being sent around southeast Queensland’s troubled water grid, in one case resulting in E coli bacteria finding its way to a Brisbane reservoir, an internal government document has revealed.

The memo, produced by officers in a state-owned water agency, details several serious water quality incidents since local councils lost control of water management in southeast Queensland last July.

It also says authorities are reluctant to promptly report incidents.

The document follows a series of blunders involving the fluoridation of the drinking supply, including a fluoride overdose in April, delays in discovering the overdose and the persistent failure to get the dosage to meet health regulations, all of which have severely embarrassed the State Government.

It reveals that in March there was a so-called level-three incident, classified as involving an impact on water customers, where hazardous E coli bacteria was detected at Karawatha reservoir in Brisbane’s south.

The five million litre reservoir services southside suburbs such as Acacia Ridge, Eight Mile Plains and Calamvale. Acting water grid manager Barry Dennien yesterday confirmed the incident, but said it was “not unusual” when benchmarked against the performance of other metropolitan water authorities.

He said the Brisbane City Council reservoir was “spot-dosed” after a second test found the bacteria.

Residents were not informed.

Government agency LinkWater, which is responsible for the pipeline network feeding the reservoirs, detected no E coli in March, Mr Dennien said.

Asked if he was satisfied with the way the E coli and other incidents were communicated, Mr Dennien said all communications were done in “an honest and transparent way”.

– the release in August of drinking water containing elevated chlorine levels in a Linkwater pipe servicing Ipswich;

– turbidity and manganese in drinking water that took nearly a week for local councils to be notified;

– another Level Three incident in December 2008 involving the chemical substance geosmin, a byproduct of algal growth, which gave drinking water a foul taste and odour.

He said the December incident, which drew hundreds of complaints from Brisbane and Ipswich residents and was reported widely at the time, was caused by severe storms in the region’s catchments.

“All authorities involved in the water grid have actively communicated in an open and transparent way with the Water Grid Manager on these incidents,” he said.

This week, Premier Anna Bligh was forced to admit that initial information she was given on a fluoride overdose at the North Pine water treatment plant was wrong.

Ms Bligh has appointed independent expert Mark Pascoe to investigate the fluoride overdose, which the Government initially believed could have affected 4000 homes in the Pine Rivers area.

However, in the latest version of events reported by Ms Bligh, the incident may have affected a YMCA camp and about 400 homes at Joyner.