For every $25 that local governments in the Washington area spent last year, $1 of it went to Metro.

That may not sound like a big piece of the pie, particularly when compared to the costs of public schools or of police and fire protection, but it is infinitely more than what transit service cost taxpayers here in 1972, which was nothing.

What this says, like it or not, is that transit has become a tax-supported public service, just like schools and police, not only here but in cities across the nation.

In the midst of last week's wildcat transit strike, when motorists were steaming along with their engines overheating on Shirley Highway and when some people could not get to work or catch a cab, it was abundantly clear that transit helps more people than just those who use it.

"One thing this strike showed. I guess, was the value of public transit here," Metro General Manager Theodore C. Lutz said wryly as the strike continued last week.

"What about the public interest?" Federal District Judge Louis F. Oberdorfer demanded of an attorney arguing that striking Metro workers had some legal claims to relief. Later, Oberdorfer said, "This has tied up a whole city." And even later, he called the walkout a "national emergency."

The Metro system, therefore, is useful. It is also the only alternative to the automobile and area leaders have decided that, with the exception of Interstate Rte. 66, there will be no more freeways within the Beltway.

However, Metro's appetite for tax money to feed its operating deficit has grown much faster as a proportion of local budgets than any other category in the local budgets.

In Montgomery County, to pick one example, the public school budget increased 12.6 percent from fiscal 1976 to fiscal 1978, while the Metro budget increased 48 percent, due in part to the opening of the Silver Spring Metro line.

City and county budget officers across the area have estimated that Metro's costs will increase by about that much again in the next four or five years - a more rapid rate of expansion that they are projecting for their budgets as a whole in most cases.

That is the key reason that the Metro board, in an unusual move, decided to take the lead last year in pumping for some kind of regional tax dedicated to Metro that would relieve the burden on the property tax, the primary method area local governments have to rais money.

Alexandria City Council member Robert C. Calhoun, in recent testimony before Congress, said that Metro costs would mean as much as a 13-cent increase in the Alexandria property tax by 1981 unless a new revenue source is provided."

That would mean that the tax bill on a $75,000 home in Alexandria would increase from $1,275 today to $1,372.50 in 1981 just because of Metro. Other changes in the tax bill would presumably ensue because of future changes in the present tax rate of $1.70 per $100 of assessed valuation or because of other adjustments in the city budget.

Whil the regional average of Metro expenditures does not appear to be a high part of local budgets on average, a closer look at those budgets and at the outside aid available for transit to individual jurisdictions gives a different picture.

In Montgomery County, Metro's bus and subway operations constituted only 2.5 percent of the county's operating budget in fiscal 1978. That includes the subsidy for operating the buses, the subsidy for operating the subway and the annual interest and interest and principal payment on bonds the county sold in the past to raise money for subway construction. The total was $13 million. Montgomery County spent $275 million public schools and an additional $190 million on police and fire, for comparitive purposes.

In Alexandria, the smallest of Metro's major partners, the Metro subsidy and bond payments in 1978 consumed fully 10 percent - $1 out of every $10 - of the city's operating budget. That was by far the highest percentage in the metropolitan area.

Arlington County was second at 7.8 percent. Everybody else - the District of Columbia and Fairfax, Montgomery and Prince George's counties - contributed less than 5 percent each of their total operating budgets to Metro.

There are other inequities across the region in the way the Metro burden is shared. Understanding those inequities gives more clues as to why most Northern Virginia politicians are such hard-line advocates for high fares and low-cost labor contracts.

In fiscal 1978, both Montgomery and Prince George's counties actually had to pay only 58 percent of their Metro expenditures from their own pockets. The other 42 percent came from federal and state aid.

Virginia localities receive federal aid too. So do all major urban transit systems in the country. But there is no state aid in Virginia and no prospect of it happening.

In a recent statement to Congress, Virginia Gov. John N. Dalton said that "it has been consistently the policy of the commonwealth not to participate in the payment of operating deficits. Our reasons . . . are based primarily on our belief that those things which determine the level and quality of service provided by any mass transit system must be determined by those who operate the system . . ." In other words, operating costs are a local problem.

Thus, while Montgomery and Prince George's counties pay only 86 percent. Arlington pays 82 percent. Almost all of that pay 82 percent. Almost all of that money comes from the real estate property tax.

The District of Columbia also pays 86 percent of its Metro costs. But the District can apply that cost against a series of taxes, including income taxes and other state-like fees not available to the suburbs, as well as to the property tax.

Many polls have been conducted in recent months by various news organizations and politicians and all of them have shown a majority of the area's residents in favor of Metro, even if it costs them more in taxes.

That fact is clearly recognized, because the anti-Metro political rhetoric of 18 months ago has virtually disappeared - except in private conversations with local government budget offiders. They are looking at the long-term cost, not the latest poll.

For example, when Metro General Manager Lutz recommended the addition of weekend and week-night service for the subway, local budget officers almost to a man recommended against it on grounds of excess cost ($2 million in the first year) and low potential ridership (nobody really knows.)

The politicians, listening to their phone calls and reading their polls and mail, overruled the budgt officers. Metro will start nighttime and Saturday service Sept. 25.

Nonetheless, the long-term reliance on the property tax for Metro expenses is a long-term threat to the stability of the Metro organization.

The difficulty in setting fares and the interminable arguments over how much each of Metro's jurisdictions should be billed for fixed costs are exhausting the patience of Metro's most reasonable board members and tying up top management for hours on subjects that have nothing to do with the quality of service, labor relations, or improving on-time bus performance.

Furthermore, the formulas for deciding those issues are renegotiated on the bus system every three months. That means the Metro board is continually arguing over something that could easily be locked in place for a year or two - if it did not so dramatically affect local tax bills.

"When we look at urban transit systems around the country, we see three with big problems: Detroit, Philadelphia and Washington," said Richard S. Page, administrator of the federal Urban Mass Transportation Administration.

Those are the three that do have a dedicated, outside source of revenue apart from the property tax to support their operating costs.

"In some ways," Page said, "I'm impressed with the strength of the Metro board. Clearly, however, it would be a lot stranger if it had a regional tax source."

The Metro board decided, after studying the problem, that it was politically impractical to expect the Maryland and Virginia legislatures, Congress and the District of Columbia City Council to agree on a metropolitan-wide tax, imposed uniformly and dedicated to Metro.

It suggested that each of the three major jurisdictions - Maryland, Virginia and the District - decide which tax would be best for it.

Generally, a 1 percent sales tax would provide more than enough money for Metro's operating costs and capital needs, as would a payroll tax. Gasoline taxes, parking taxes and some other fees fall short of providing full operating deficit relief, but still reduce the burden on the property tax.

Furthermore, some jurisdictions understandably want the control of Metro's operations that they have by controlling the flow of revenue.

Northern Virginia politicians made a valiant effort to get a 1 per cent regional saels tax through the Virginia legislature last year and fell only one vote short in the House after winning in the Senate.

No serious effort was made in the Maryland legislature last session to win a approval for such a tax because this is an election year in Maryland.

It is also an election year in the District, which seems to be waiting to see what the suburbs will do.

For the short term, at least Metro is stuck with what it has - the property tax, levied unevenly and unequally across the region and doled back to transit in the form of voluntary contributions.

The Metro board's members are sent to that organization from elected local councils and boards and in the final analysis, have to represent their localities, not their region.

In a report last December, a task force of the influential Federal City Council said that "many of the difficult issues faced by the Metro board are not truly within that board's power to resolve. They depend, instead, upon decisions by a multitude of individual local jurisdictions . . ."

Joseph S. Wholey, the board chairman agrees. "Board members," he said, "don't see themselves as free to act."

Wholey does not favor some sort of super-regional body one step removed from local politics and holding taxig authority as the answer here. "I don't like regional governments," he said. "What's best for Virginia may not be best for the District of Columbia." As a practical matter, it would take a political revolution for one to occur in this region.

Furthermore, said Wholey, "I don't think Metro's problems are organizational. I think they are financial."