Americans are used to drinking water from the kitchen tap, though water utilities may be vulnerable to terrorist attacks or natural contaminants.

Now, thanks to CANARY Event Detection Software, an open-source software developed by Sandia National Laboratories and the Environmental Protection Agency (EPA), public water systems can be protected through enhanced detection of such threats.

"People are excited about it because it's free and because we've shown it works really well. We would love to have more utilities using it," said Regan Murray, acting associate division director, EPA's Water Infrastructure Protection Division at the National Homeland Security Research Center.

The software tells utility operators whether or not something

is wrong with their water within minutes. The mechanism is also improving water quality by giving utility managers more comprehensive real-time data about changes in their water.

CANARY is currently being used in Cincinnati and Singapore, while Philadelphia is testing the software system.

A number of other US utilities are also evaluating the use of CANARY. Sean McKenna, the Sandia researcher who led the team that developed CANARY, said people began to pay attention to the security of the nation's water systems after 9/11.

The software, which runs on a desktop computer, can be customised for individual water utilities, working with existing sensors and software, McKenna said.

While some utilities monitor their water using real-time sensors, many still send operators out once a week to take samples, said David Hart, a Sandia software developer for CANARY.