But there is no escape. The officers can wait - even up to 12 hours if necessary - for these suspects' bodies to do what comes naturally. Suspects are counselled into cooperating and encouraged to help themselves at the water dispenser.

They are allowed to drink only 'Singapore tap water' and nothing else, to shield officers from allegations that the drinks of those who fail the test were spiked. The officers can fall back on the law if coaxing fails: Under the Misuse of Drugs Act, failure to provide a urine sample can land one in jail for up to 10 years and a fine of $20,000.

As long waits stretch out the turnaround time before officers can return to the field, it is important that the tests can be done even with small amounts of urine, the officer added.

Technology has helped. Regardless of the number of drugs the sample is tested for, officers now need just three small bottles of urine, which can be filled up during a single trip to the toilet. In the past, two bottles were required for each drug type.

The results of the instant test have more than 90 per cent accuracy. The remaining samples are sent to the Health Sciences Authority for a conclusive analysis.

The tests do not lie even when suspects guzzle lots of fluids to dilute the concentration of drugs. The officer said: 'They can drink a lot of water and pee and pee and pee before they come for the test, but we can still detect, because you are basically what you eat.'

joolin@sph.com.sg

This story was first published in The Straits Times on Oct 27, 2008.

For more The Straits Times stories, click here.

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