A flood of illegal drugs, primarily heroin and cocaine, has fueled a nationwide crime wave that is causing many Americans to lose faith in the ability of government to protect them, federal officials and law enforcement experts told a conference here this week.

"It is the inundation of drugs--some of which are grown here--that is eroding public confidence and corrupting public officials," FBI Director William Webster said at the three-day conference, which was sponsored by the Washington Journalism Center.

The result of that erosion of confidence has been the burgeoning of private anticrime efforts, including security guards, guard dogs, bars and alarm systems, self-defense classes and handgun sales. Officials estimated the private security industry already does

0 billion in business a year--and is growing.

"I think we're on a continuum where every day, public confidence diminishes in the ability of the government to deal with their public safety," said Sen. Joseph Biden Jr. (D-Del.), ranking minority member of the Senate Judiciary Committee.

"The longer we wait, the more likely Americans will feel they need to go to a store and get a gun for their car or bedroom or kitchen," Biden said. "I think we're reaching the breaking point."

According to Francis M. Mullen, acting administrator of the federal Drug Enforcement Administration, there are about 492,000 known heroin addicts in the United States and about 4.4 metric tons of heroin were smuggled into this country in l981. He said that there are about 15 million cocaine users and that about 60 metric tons of cocaine, mostly from Colombia, made it to the United States that year.

More than 90 percent of the supply of drugs, he said, was imported through organized crime networks. When asked if there had ever been an organized crime figure working as a "mole" within the DEA, Mullen said "yes," but did not elaborate.

Between 40 percent and 60 percent of all serious crimes that occurred in the United States in l981 were drug-related, according to estimates by law enforcement officials at the conference.

Crime was also related to such diverse factors as warm weather and the nation's demographics. Crime trends showed, officials said, that there are more crimes committed during summer months than winter months and that persons between the ages of 14 and 25 are more likely to commit crimes than persons in any other age group.

That demographic trend led Newman Flanagan, president of the National District Attorneys Association, to predict that the crime wave would bottom out by the end of the decade, as the current young generation, which represents a miniature "baby boom," grows older.

Fear of crime, experts noted, has given rise to increases in public appeals for stiffer anticrime legislation, including the abolition of parole, imposition of mandatory sentencing and the death penalty--none of which has been proved to reduce crime.

Analysis of the nation's criminal justice system, reveals that emphasis on the "system" is misdirected because there is no system, just a "habit of bad practices that hasn't changed for 50 years," said Sam Dash, former Watergate commmittee chief counsel and currently a law professor at Georgetown University.

Citing the results of two presidential commissions on crime, from l957 and l967, both of which showed that most crimes go unreported and that many of those that are reported go unsolved--including 48 percent of all reported rapes--Dash concluded:

"The system has very little impact on crime. What we're talking about in terms of what police do, what prosecutors do, what courts and prisons do is simply retouching a tiny part of the crime problem that comes to our attention. The rest of it is all outside the system."

Dash added, "If you look at who gets caught up in the system--the jails and prisons--it's basically your poor, black amateur, the losers in the crime game. However, they are not costing society nearly as much as white-collar criminals or organized crime."

Following a steady reduction in police officers since l960, fewer streets are being patrolled. Thus, many neighborhoods have turned to watch groups, which experts generally applaud. However, they point out, the key to a successful neighborhood watch group is a close-knit neigborhood, based on tight families, where youth are disciplined and watched by adults, not necessarily their parents.

Yet, according to Lynn A. Curtis, president of the Eisenhower Foundation for the Prevention of Violence, it is the deterioration of neighborhoods, with their educational and support systems, that is the root cause of crime. With unemployment reaching ll percent, maintenance of neighborhoods will prove even more difficult in the years ahead, Curtis said.

Nonetheless, according to Webster, statistics released by the FBI show that crime in America reached an all-time high in l980, began leveling off in l981 and showed a five percent decline during the first six months of last year. "That's encouraging," Webster said. "But we still must ask ourselves: encourgaging compared to what?"