PERHAPS IT'S a sign of the times that so many homeowners and merchants feel the need to equip their homes and businesses with security alarm systems. But the growth in alarm systems may be outpaced by the increase in false alarms, and that development -- if allowed to run unchecked -- could prove costly for everyone. The Montgomery County police report that 97 percent of the alarm calls they receive are false. The District of Columbia police responded to 70,000 calls in 1989; 90 percent of them were false. Last year, Fairfax County police handled 37,400 false alarms.

These are more than mere nuisance calls. Fairfax estimates that false alarms cost county law enforcement $1.3 million. Montgomery County said $800,000 in vehicle costs and officer salaries alone was wasted last year on such calls. There are other costs, too, besides the drain on the limited financial resources of the police. Responding to a false alarm may mean that a real alarm elsewhere has to wait. Police officials also fear that repeated responses to false alarms can breed complacency in police officers, who then end up unprepared for the serious call.

The chief reasons for the rise in false alarms are easy to pin down; they are simple to correct, as well. They range from defective alarms systems and improper alarm installations to owners' unfamiliarity with the working of their alarms. Careful reading of the manual or competent repair work can solve two of these. The defective system that operates with a mind or nervous system of its own, however, is a manufacturer's problem that the consumer ought not bear. But another producer of false alarms is more symptomatic of why some people install alarms in the first place: the fear that leads homeowners deliberately and repeatedly to activate their alarms to check police response times.

Law enforcement agencies around the region are sagging under the burden of false alarms and are stepping up their efforts to eliminate the excesses. Montgomery County police announced on Tuesday that they will fine the errant homeowner $30 for each false alarm exceeding three a month or eight a year. Those who deliberately set off alarms to clock the police will get hit with misdemeanor charges. Fairfax will impose fines of $20 to $150 against homeowners and businesses beginning next January. The District police will join with the others later this year by imposing fines on repeat offenders -- ranging from $10 to $60 for more than eight false alarms a year. Where it is determined that false alarms are caused by defects inherent in the system, the manufacturer should be held responsible for making the corrections or at least bear the cost of the fines. Nonetheless, tough enforcement on a small number of repeat offenders is probably needed if police service is to be available where it's really needed.