NHS Highland has confirmed that low levels of Legionella were detected in water supplies at Invergordon County Hospital in January.
Following the discovery the health authority said it immediately put safety measures in place to "prevent harm to patients and staff".
An NHS Highland spokesperson said: "As part of our regular and routine testing for the presence of bacterial in water supplies within NHS Highland facilities, a limited number of samples tested positive at Invergordon County Hospital in December. Legionella was not detected at that time. Measures were put in place in December to ensure that patients and staff were provided with safe water, including bottled water."