MR FRANCIS Cheng ("Why water costs more despite unchanging prices"; June 22) and Mr Jeffrey Law Lee Beng ("Don't be complacent about water sufficiency"; Forum Online, June 27) both extolled the fact that water is not only a precious resource but also a basic necessity that needs to be conserved and used judiciously and not wasted.

The water conservation tax, at 30 per cent on the amount consumed, is to discourage excessive use and deter wastage.

To be more effective, the tax should be tweaked to encourage more consumers to use the least possible amount of water.

For instance, those who consume at or below a pre-determined subsistence level could earn an exemption from the water conservation tax.

As for high-volume consumers, the water conservation tax can be tiered progressively, according to various levels of usage above the subsistence level.

This is a more equitable arrangement, in which those who use water for the bare necessities are not burdened with the levy, while the affluent - who may need to wash cars, fill up pools, water gardens and so on - will have to pay more.

Another solution could be for the authorities to carry out research and trials to see if tweaks to the plumbing system have an effect on reducing water consumption.

Chin Kee Thou