Don't read this before you eat lunch!

For as long as we can remember, tourists heading for Mexico have been warned: ''Don't drink the water!''

Well, if you're planning to fill up a couple of jugs with tap water in Los Angeles or San Diego before you head to Tijuana, you might want to think twice.

According to a report in today's Wall Street Journal, L.A. is poised to announce plans to recycle 4.9 billion gallons of treated wastewater to ''drinking standards'' by 2019.

A number of other major metropolitan areas facing water shortages are moving in the same direction: San Diego recently approved a pilot project to pump treated wastewater into its local reservoir, and Miami-Dade County, Florida, is planning a system that will pump 23 million gallons of recycled wastewater into an aquifer that will feed wells in the area.

''Treated wastewater'' is a polite way of saying ''sewage.''

This euphemism probably was coined by the same guy who came up with ''certified pre-owned vehicle'' to describe a used car with 98,000 miles on the odometer and cigarette burns on the front seat, currently being offered by your local dealer for the highly discounted price of $12,500 (the warranty expires as soon as you pull off the lot).

Wastewater recycling initiatives have been put forward periodically in recent years, as major population centers have continued to expand while water resources remain, well, stagnant. These projects usually have been pushed off the agenda by what the Journal calls ''the yuck factor'' -- critics labeled them ''toilet to tap'' proposals.

Not any more. The rate at which demand is outpacing supply apparently has hit a tipping point that renders the ''yuck factor'' irrelevant.

Besides, even if ultra-hygienic types in L.A. and San Diego manage to pull together a movement to beat back the sewage recycling plans, they still will be ingesting treated wastewater: 400 million gallons of it is discharged into the Colorado River every day.

Of course, Angelenos always will have the option of jumping into their corn-powered vehicles and taking a four-hour excursion on the freeway to purchase a month's supply of bottled water at $5 per gallon jug.

Try not to notice the friendly convenience store clerk filling the jugs with a hose behind the Quik-Chek.