Everything in this chapter, applied to one problem: a small island that cannot store all the water it needs.
Water is essential to life — our cells, tissues and organs use it to regulate temperature and keep working. Industries need it to fabricate, process, wash, dilute, cool and transport products. Homes need it for cooking, washing and cleaning, and activities such as swimming and canoeing need it too.
But as a small country, Singapore does not have enough space to collect and store all the water we need. In 2015 the World Resources Institute ranked Singapore among the most water-stressed countries in the world, and one of eight countries most likely to face disruptions in water supply by 2040.
The answer is not one solution but four.
The three steps of NEWater
Rainwater is collected through a network of drains, canals and rivers and channelled to 17 reservoirs. Singapore also imports water from Johor, Malaysia.
Both are piped to the waterworks, where the water is chemically treated, filtered and disinfected. This removes harmful bacteria and makes the water clear, odourless and safe. It is then supplied as tap water, well within World Health Organisation guidelines for potable water — safe to drink straight from the tap.
NEWater is ultra-clean, high-grade recycled water, made from treated used water. Used water from homes and industries is collected through sewers and sent to water reclamation plants; the treated used water then goes to NEWater plants for further purification in three steps:
NEWater has passed more than 150 000 scientific tests and is well within WHO guidelines. It is mainly supplied to industries, and during dry weather it is also added to our reservoirs.
Desalination obtains pure drinking water from seawater. It can be done by distillation or by reverse osmosis.
Singapore therefore desalinates using reverse osmosis instead. This is the clearest example in the chapter of the point from Lesson 1: physical properties tell you what could work, but cost, reliability and environmental impact decide what is actually used.
In reverse osmosis, pre-treated seawater is pumped through partially permeable membranes at high pressure. Each membrane is a thin material with very small pores that allow water particles through but not salt particles — and which also stop microorganisms such as bacteria, and chemical contaminants. Pure water is obtained on the far side.
Water is readily available here but remains a scarce resource, so conservation matters — we conserve by reducing wastage and reusing water.
| Reduce | Reuse |
| Turn the tap off while brushing your teeth · turn the shower off while soaping · wash vegetables in a container · use half-flush · wash the car with a pail rather than a hose · use a water-efficient washing machine on a full load | Water plants with the water used to wash vegetables or fruit · reuse washing-machine water to flush the toilet or wash the floor |
We can also protect our water resources by not throwing litter or releasing animals into waterways or reservoirs.