THE article ("Dry spell ahead may see water rationing"; last Saturday) reported that Singapore may have to take measures to conserve water during a predicted dry spell over the coming weeks.
One strategy is to make water supply intermittent, such as shutting the main water supply to all or parts of the network at certain hours of the day.
Such a measure, however, comes with problems.
It may trigger negative pressure, which carries the risk of water contamination when sediment within the distribution network is churned up and carried in water when the supply resumes.
Air may also be drawn into the system, causing air locks or water hammer (pressure surge).
Also, water rationing may not result in significant water conservation.
Consumers would fill up bathtubs, basins and containers in anticipation of water rationing. They also tend to leave taps in the "open" position so they will know when supply resumes.
A great deal of water may be wasted through these open taps after the supply is restored, and when excess stored water is disposed of.
Chia Wai Chon
Operations Manager
Singapore Plumbing Society
One strategy is to make water supply intermittent, such as shutting the main water supply to all or parts of the network at certain hours of the day.
Such a measure, however, comes with problems.
It may trigger negative pressure, which carries the risk of water contamination when sediment within the distribution network is churned up and carried in water when the supply resumes.
Air may also be drawn into the system, causing air locks or water hammer (pressure surge).
Also, water rationing may not result in significant water conservation.
Consumers would fill up bathtubs, basins and containers in anticipation of water rationing. They also tend to leave taps in the "open" position so they will know when supply resumes.
A great deal of water may be wasted through these open taps after the supply is restored, and when excess stored water is disposed of.
Chia Wai Chon
Operations Manager
Singapore Plumbing Society
