Ways to boost water sufficiency

I read with interest various articles about Singapore's water sufficiency, especially with regard to creating reservoirs underground in our rock caverns ("PUB going underground to store water", June 29; and "Digging deep in Singapore for space solutions", ST Online, June 17).

I would like to know how much storage capacity we can achieve by doing so.

Perhaps we could also consider the following ways to boost our water sufficiency:

- Build two land bunds from each end of Pulau Ubin to link to our mainland, and create a huge reservoir.

- We could also consider digging much deeper into our existing reservoirs. This could increase our water holding capacities many times.

Ng Tsorng Chinn