At Admiralty West Prison, some 250kg of rice has to be cooked for every meal.
It used to take six washes before each 25kg batch of rice was fit for consumption, but a filter fashioned out of discarded materials has reduced water use. The same amount of water that washed one batch of rice can now wash three or four, saving the Singapore Prison Service (SPS) more than $4,300 a year.
The man behind this filter is Deputy Superintendent of Prisons 2 (DSP2) Kalaivanan Visvalingam, 44. Known as "Mr Innovation" among his superiors, he has won more than 20 awards over 18 years in the prison service.
"There are many ways to do things. If we keep doing things the same way, we are not going to improve," said the operations officer at Admiralty West Prison.
"For everything that we do, I want to simplify the processes, of course not forgetting security and safety issues," he said.
The master of materials has a long list of inventions to his name, including brooms made of old straw mats and mops made of "good morning towels", which the inmates leave behind when they are released.
Although no longer in use, these mops wore out slower than traditional mops on rough cement floors and saved the prison service hundreds of mops a year.
He also came up with the fish-tank shaver kit in 1999 to simplify the process of accounting for shaver blades distributed by assigning a "bubble" to each inmate's shaver. It is still in use today, saving the SPS around $25,000 in man-hours a year.
His latest project, the rice filter, won him a Home Team Innovation Champion Award (Platinum) at the Ministry of Home Affairs' biennial Excel Fest earlier this year.
But his background was not in design or engineering. Instead, he studied banking and finance at the University of Central Oklahoma in the United States.
After returning to Singapore, he was unable to find a job in a bank.
He did a teaching stint but was unable to settle into the job. It was a friend's suggestion that led him to apply for a position at SPS, and he got the job.
Almost immediately he was asked to be part of a group under the Work Improvement Teams (Wits) scheme at the now-defunct Khalsa Crescent Drug Rehabilitation Centre, where he discovered his interest in innovation.
"I joined because of the pay," he admitted. "But now I stay because I like the job."
His first innovation was a flexible kitchen trolley with multi-directional wheels - something that seems commonplace now.
"In those days, nobody came up with new things. After that, trolleys with wheels became nothing," he said with a laugh.