In signing on as a supporter of a Democratic-sponsored $2.5 billion child care bill, Sen. Orrin Hatch apparently believes that even a flawed bill is better than no child-care legislation at all. And there is no question that more and better child care is desperately needed in America.

Certainly, it would be better if more women were staying home taking care of their families, but that simply isn't the case. A majority of situations involve single-parent families headed by women or families where the husband earns less than $15,000 a year. The economic realities must be faced and dealt with.By the end of 1987, more than 57 percent of all women with children under the age of 6 were in the work force. About half of all women with children under 3 were working. Yet for the 12 million youngsters whose mothers are employed, there are only 2.5 million licensed day care openings. In many cases, the cost is more than low-income families can afford.

In Utah, there are only 18,000 day care slots to handle a critical need of 100,000. For working women everywhere, child care is usually the biggest single problem they face.

The need for adequate, modestly-priced child care has become crucial, and it's going to get worse. Nearly everyone agrees on that, but the disagreements arise over how to provide that care.

If the federal government is going to get involved, Hatch would prefer that it do so at arms length. He would prefer federal funding be done in the form of block grants to states, which could then tailor programs to meet their own needs. Hatch's own version of child care support would have cost $250 million the first year.

Yet that modest approach has fallen by the wayside in favor of the so-called ABC bill - Act for Better Childcare - which will cost 10 times as much as Hatch's proposal in the first year alone and threatens to become one of those entitlement programs that are huge, open-ended drains on the federal budget.

Hatch's reluctant signing-on as an ABC supporter represents a choice between two unsatisfactory alternatives, namely, that the nation can't really afford the ABC legislation, but it can't afford to ignore critical child care needs, either.

As Congress grapples with budget deficits and new programs like ABC, it should make every effort to keep the lid on spending and approach child care with an eye toward a less-expensive trial period to iron out some of the inevitable problems that will surely crop up.