THE mother of an Allora girl who contracted cryptosporidiosis says she's at a loss to explain how her daughter fell ill after Southern Downs Regional Council's water supplies tested clear of any contamination.

Test results received from Queensland Health have cleared the Warwick and Allora water supplies of any cryptosporidiosis infection.

Letesha Scotney, whose 18-month-old daughter Alani contracted the virus last month, remains adamant the water is to blame.

"I have read multiple stories stating there is nothing in the water but my question is how did Alani get it then?" she said.

"I have spoken to a few people and they have said it must be something all the people infected have come in contact with."

Ms Scotney said there was "no room for another explanation" and wanted to find out what was responsible.

"I want someone to be held responsible for the long and stressful two and a half weeks that has affected Alani both mentally and physically," she said.

"She (Alani) is still short of energy and still trying to put back on the weight she lost and I myself am still trying to recover from the exhaustion and weight loss caused dealing with it all," she said.

The council took water samples from Ms Scotney's home, as well as the Allora reservoir, Allora water supply trunk main at Willowvale and the Allora swimming pools.

Mayor Peter Blundell said council staff responded quickly to Ms Scotney's concerns, doing extra e.coli water tests and taking samples for cryptosporidiosis and giardia.

"Nine samples were obtained over two sample periods and sent to Queensland Health for analysis, and I'm pleased to confirm that all test results have been returned negative, clearing the water supplies of both cryptosporidiosis and giardia," he said.

"Given the negative result, no further specific tests will be conducted for cryptosporidiosis and giardia.

"However, we will continue to carry out our regular water quality testing in accordance with the Australian Drinking Water Guidelines."

Samples were also taken from the Warwick water treatment plant and Mel Gibson Park, at Cinema Heights.

Cryptosporidiosis can be spread by faecal-oral transmission including person to person, animal to person, waterborne and food borne transmission.

Control methods include practising good personal hygiene, taking care when disposing of human or animal faeces, and ensuring careful hand washing after handling animals.