Mr Francis Cheng ("Why water costs more despite unchanging price"; June 22) may have misunderstood our commentary on June 16 ("Time to tighten the tap on cheap water").
We are, of course, aware of how electricity and gas prices are calculated.
Even after all these calculations, if the prices were simply indexed to inflation for 2000-2014, the difference with the current tariffs and inflation-adjusted prices for electricity and gas would be less than 4 per cent after 14 years.
Mr Cheng also assumed that the water conservation tax was not included in our calculation.
In fact, it was.
This tax was last adjusted in 2000.
Our commentary discussed national averages.
For all such averages, there would be wide variations for individual households, depending upon numerous social and economic factors and household conditions.
Mr Ong Yoke Fei said that water price increases will be futile to reduce water consumption ("Go for hearts and minds, not the wallet"; June 22).
Experience from all over the world categorically shows that pricing and economic incentives are the main drivers of per capita water use.
This should be supplemented by public education and awareness. They are not either/or solutions.
Asit K. Biswas (Professor)
Cecilia Tortajada (Dr)
Lee Kuan Yew School of Public Policy