Millions of Americans will suddenly become eligible for drug and alcohol treatment coverage in January, threatening to overwhelm the system.

As elements of the Affordable Health Care Expansion Act of 2011 take effect, some three to five million people — from homeless heroin addicts to suburban wine enthusiasts — would gain some sort of coverage as part of an expansion of the federal-state Medicaid program.

As the federal government presses more states to help expand Medicaid, the new law would also provide subsidies to help many people buy private coverage, with the new law mandating such treatment as an "essential health benefit" for most commercial health care plans.

"This is probably the most profound change we've had in drug policy ever," said Michael Botticelli, deputy director of the Office of National Drug Control Policy. "We know one of the most significant reasons for the treatment gap is folks who don't have insurance or who have an inadequate coverage package for substance use disorders."

Some 23 million Americans today suffer from clinical-level addiction to drugs and alcohol but only 10 percent receive treatment. Aside from the lingering social stigma of behavioral health treatment, one-quarter of addicts lack health insurance coverage, compared to a rate of 16 percent for the rest of the population, according to the National Survey on Drug Use and Health.

Moreover, many lower- and middle-income Americans presently lack the money to receive treatment given that employer-based schemes cover only half of the population with the rest often making too much money to qualify for Medicaid programs intended for the working poor. With the new law, 20 states now plan to expand their programs, placing an additional 3.8 million addicts into the system, according to the AP.

With nearly all state jurisdictions in the mix, as administration officials predict, the number of newly eligible addicts would rise to approximately 5.5 million, exciting advocates and some addicts alike.

"There is no illness currently being treated that will be more affected by the Affordable Care Act than addiction," said Tom McLellan, CEO of the nonprofit Treatment Research Institute and President Barack Obama's former deputy drug czar. "That's because we have a system of treatment that was built for a time when they didn't understand that addiction was an illness."

Ashley Lore, a 30-year-old mother in Portsmouth, OH, lost custody of her 4-year-old daughter when she was jailed as a result of her heroin addiction. "It's the chance to clean up and not use anymore, so I could live a stable life," she said. "If I get into treatment, I get visitation to my daughter back. And I get her back after I complete treatment."

However, Josh Archambault of the Pioneer Institute, a nonpartisan public policy research center in Boston, warns of the crunch ahead. "Advocates just get so excited, but at some point, reality is going to hit and they'll find it's not all it was cracked up to be."

The rush for limited resources by newly eligible beneficiaries may mean months-long waiting lists for many, exactly the kind of horror stories cited by opponents of the new health care law. And naturally the experience would be different from state to state, with dramatic differences in resources.

In Illinois, for example, 92,000 people presently receive treatment with nearly 235,000 uninsured people to be newly eligible. Dan Lustig, vice president of addiction facility Haymarket Center in Chicago, says the state cut funding last year. "We had clients literally pleading for services" after they cut the number of beds. "Some were sleeping on our front steps."

However, Maryland is home to some of the highest income Americans in the country, with seven of the top 10 richest counties located in the Washington, DC, area. The state last year spent $100 million in addition to federal help for their drug addicts and alcoholics, compared to poorer states that spend nearly nothing more than the federal contribution.

As Maryland joins the Medicaid expansion next year, the number of addicts eligible for state-sponsored coverage would double to some 41,000. Dr. Joshua Sharfste, the state health secretary, told the AP that the state would prefer more residents seeking treatment, given their level of resources. "We want people to get substance abuse treatment," he said. "It allows them to gain independence and transform their lives, and it leads to less criminal behavior, more employment and better outcomes for individuals and their families."

Maryland increased addiction treatment spending, in combination with the federal contribution, by 165 percent from 2009 to 2011.

At the moment, 15 states plan to not join the expansion; an addition three leaning towards joining and five remain undecided.