Mr Seah Yam Meng said Singapore should focus on desalination plants for its water needs (Focus on desalination as main tap, Feb 8).

We need to be able to produce more potable water to meet our growing needs and reduce the dependency on neighbouring countries for freshwater sources.

I agree that the advantages of desalination are abundant. The reverse osmosis technology is proven beyond any doubt. It is stable, modular and scalable.

However, we also need to look at the flip side.

First, it is expensive. Approximately 2 kilowatt hours of energy is used to produce 1 cubic m of desalinated water. The membranes that are used to sustain the osmotic pressure are costly both in terms of production and maintenance.

And the process also removes certain vital minerals. Remineralisation has to be done after desalination, which adds to the cost.

Though Mr Seah said that Singaporeans are ready to pay more for water, I think it is not just about the maths.

Desalination has its own overheads to manage. The highly concentrated brine waste generated needs to be disposed of safely. It cannot just be dumped back into the sea. The marine ecosystem surrounding Singapore is delicate and fragile, and it warrants the utmost care.

It is true that desalination plants are running successfully in many Middle Eastern countries, which have very minimal or no freshwater sources.

Singapore has tried every possible technology, source and means to produce potable water. Apart from drawing freshwater from Malaysia, we have wastewater recycling plants and four desalination plants - the largest of which opened last week.

I think Singapore is carefully weighing its options and treading carefully, one step at a time, with its future needs in focus.

Whatever technologies we implement and however many plants we install, people need to play their part by using water wisely and be mindful of not wasting it.

Ramamurthy Mahesh Kumar