U're missing something here... u're assuming that rainwater is
directly potable, which it is not...
Indeed, if rainwater has indeed increased as u say, I would be
concerned about the quality of the reservoirs because storm
run-offs that feeds into such catchment areas go through some of
the filthiest urban features on the island... building exteriors,
streets, storm drains, etc etc...
Water recycling is basically an extension of water treatment. At
the end of the day, to ensure safe, consistent water quality, u
still need to filter and chlorinate the stuff.
Water recycling is just going one step further to ensure that
should it be necessary, alternative sources of water can be tapped
to ensure consistent supply through reverse osmosis. It is
foresight.
Its quite dangerous to trust our national survival to the whims and
fancy of mother nature.