CULIACAN, Mexico — The colossal water cistern set in a clearing in a hilly, heavily forested area can hold 25,000 liters of water — enough to irrigate a major food farm.

But follow the pipes down and there, beneath a corrugated iron roof and resting on hay bales, and its real, more sinister purpose is revealed.

Here in the heat of northern Mexico, the factory churned out record amounts of methamphetamine — known on the American streets as crystal meth, or ice — a drug that has torn through the United States and become the biggest growth area for cartels south of the border.

U.S. police have known for several years that the cartels were gaining strength in the meth trade, taking over a business that used to be run by American biker gangs that cooked up crystal in buckets and bath tubs.

But a recent series of raids by the Mexican military revealed that the cartel meth factories have become even bigger and more sophisticated than previously thought.

Busted in June, the factory in the clearing near this unwieldy Mexican city is estimated to have produced 40 metric tons of meth, worth some $1.4 billion on American streets, in just two months before it was shut down — making it the largest operation of its kind to be exposed in the continent.

Huge barrels with the precursor chemical pseudoephedrine also fill the factory, unleashing a foul smell throughout the clearing.

Next to the vats and barrels stand rows of towering mobile gas tanks and a tangle of electric cables sprawling from a large generator.

“Mexico now has some massive and very sophisticated operations. We call them super labs,” said the Drug Enforcement Agency’s Elizabeth Kempshall, special agent in charge of the Phoenix Division.

Kempshall follows the meth production in Mexico because tons of the produce are trafficked through her jurisdiction in Arizona.

This vast supply has helped boost consumption of the drug — which looks like a white flaky crystal and can be smoked in pipes as well as injected or snorted.

Meth is now the most popular hard drug in America’s Midwest and West, ahead of cocaine and heroin, according to the DEA.

This surge has come about as gangsters have developed new, concentrated forms of meth that are more potent than any other drugs on the market.

“You smoke meth and it can give you a high twice as long as crack cocaine,” Kempshall said. “While crack cocaine focused on the inner cities, meth has swept the whole nation, especially the suburbs.”

The euphoric effect of crystal can allow people to work for days without rest, fuel hectic parties and give users unstoppable libidos.

But addicts soon fall foul of the drug’s longer lasting effects, suffering chronic paranoia, violent tendencies and tooth loss — known as meth mouth.

“Meth can make you rob and fight without thinking about it. It just amplifies the real evil side of people,” said Craig Stuart, a stocky 25-year old addict, recovering in a rehab center in Phoenix.

The dollars spent by junkies such as Stuart provide immense wealth south of the border.

In 2007, police swept on a Mexico City mansion to find $207 million piled up in huge mountains of notes in what the DEA said was the biggest cash bust in world history.

The homeowner Zhenli Ye Gon, a Chinese national, was later arrested in the United States, where he is now standing trial for selling raw chemicals to cartels for the production of meth.

Such immense profits lead to bloody turf battles in a country where the minumum wage is just $5 a day.

Nearly 4,000 people have been killed in drug-related violence in Mexico this year despite the army patrolling the streets to keep order.

The meth trade has also helped spawn new ultra-violent gangs such as La Familia Michoacana, a crime syndicate based in the lush highlands of western Mexico.

Emerging in 2006, La Familia is alleged to have produced hundreds of tons of crystal in its rolling hills and used the money to finance an army of killers to protect its trade.

After the federal police this year busted 39 meth labs belonging to La Familia and nabbed some of its kingpins, the group hit back hard, its gunmen attacked police bases across the region with grenades and assault rifles.

They then kidnapped 12 police off-duty officers, tortured and shot them, and lined up their corpses on a road.

“Try and arrest another one of us,” said a note in scrawling handwriting next to the bodies. “We are waiting for you here.”

More GlobalPost dispatches on the Mexican drug war:

Putting the 'war' back into drug war

Mexican cartels go global

Obama's other surge

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