It is important to save water ("Use less water, PM reminds as reservoir dries up"; Sunday). But increasing water prices to curb usage may not be an equitable solution ("Timely call to save water"; Thursday).

Increasing water prices across the board will see those with low usage subsidising those with high usage.

As people become more affluent, they tend to use more water. Those in the lower-income group tend to use less water. So if prices increase, the poor will also pay a higher price per cubic metre, regardless of their efforts to save water.

Unlike health insurance premiums, which depend on risk pooling, water usage and pricing depend on how much each household consumes - a reflection also of the effort put in to save water.

A better solution is to have a tiered pricing system.

If a household's water consumption is below the national average, the rate chargeable should be lower, together with a lower waterborne fee and water conservation tax, as a reward for conserving water.

Another solution is to follow the model of tradable carbon credits used in efforts to lower carbon emissions: Allocate the water supply for each household and company; those which use less than the allocation can trade their excess credits for money or vouchers, or keep them as surplus for future emergency use.

It is also important for the public to look out for water wastage in public areas. For example, it is not uncommon to find leaking taps or water pipes in community centres, hawker centres, shopping malls and void decks.

National water agency PUB can also work with other government agencies, such as the National Environment Agency and the Meteorological Service Singapore, to more accurately predict likely shortages during hot weather or dry spells due to climate change.

This water risk management will help Singapore build the appropriate water storage or generation infrastructure, without the country having to depend on external sources such as Johor's Linggiu Reservoir.

Francis Cheng