THE HOUSE last week wisely defeated a proposal to finance expansion of the Superfund in part through a small value-added tax. The first resort to such a sales tax by the federal government would be a momentous step, and this one had been put forward almost by default. There is still a VAT in the Senate version of the bill, but the Senate also agreed by voice vote to a nonbinding amendment by Jesse Helms urging its conferees to bring back a financing mechanism "which does not contain the value-added tax." The conferees, when they meet next year, should follow that instruction.

The Superfund program is the effort to mop up and prevent leaks from industrial dumps, of which there are thousands across the country. Virtually everyone favors its expansion. The administration has proposed $5.3 billion for the next five years, the Senate $7.5 billion, the House $10 billion. But no one wants the program to add appreciably to the deficit, and there has also been uneasiness about laying too much of the additional burden on the oil and petrochemical industries, which (because so many chemicals derive from oil, and it was thought these companies could pass along the costs) were specially taxed to finance the smaller program in the past.

A baby VAT seemed to answer all of these concerns -- a tax so diffuse no one would feel it, of only a few hundredths of 1 percent, on only the products of large manufacturers. Chairman Bob Packwood of the Senate Finance Committee explained last summer how the panel backed into the provision. "This . . . tax was added because we turned and turned and turned to dozens and said: 'Where else do you want to get the money?'" he said. "This administration that claims to be adamant against the deficit says 'Get half of it out of the general fund.' They could not find any other tax. We go to everyone who opposes the . . . tax and say, 'Do you want to increase the feedstock tax?' 'No.' 'Petroleum tax?' 'No.' 'Special manufacturers' corporate surtax?' 'No.' 'Where?' 'Oh, I don't know. But don't tax me.'"

But in the House, Ways and Means Chairman Dan Rostenkowski, opposing a bill from his own committee, took the position that "taxation should be based on ability to pay and not consumer spending. . . . We should not let the camel's nose under the tent just because the proposed tax rate is low and the spending objective is noble."

The administration also is opposed to a VAT to finance Superfund, and has threatened a veto. The House has provided the conferees with an alternative. The amendment by Rep. Tom Downey, approved 220 to 206, would spread out the cleanup cost by taxing crude oil, petrochemical feedstocks and waste producers, and by dipping into general revenues as well. There has been a lot of talk about a larger VAT as an answer to the deficit; there will be more such talk next year. The House vote was by no means a decisive repudiation of the idea. But as Mr. Rostenkowski noted, "any VAT is regressive," in that it will fall hardest on the poor, and "any VAT-like tax is a money machine." You don't turn on one of those without an urgent reason, and without thinking much more carefully about it.