A proposal to raise D.C. water and sewer rates by 35 percent drew fire from the chairman of the City Council's finance committee yesterday, who scolded officials for not being able to collect water and sewer charges already outstanding.

The measure, proposed by Mayor Marion Barry, would raise the average consumer's yearly water and sewer payment from $135 to $168.

During a poorly attended public hearing on the proposed increase, Council member John A. Wilson (D-Ward 2) told William F. Johnson, acting director of the Department of Environmental Services, that the agency should concentrate on its past billing and collection problems instead of seeking to increase rates.

Wilson said the department had failed to collect at least $10 million owed the city in overdue water and sewer charges. In addition, the agency must collect another $21 million in current charges by Sept. 30, the end of the fiscal year.

Johnson said the agency had begun a stepped-up drive to collect the outstanding money, and had even shut off water service at least temporarily to around 70 customers. "We believe we can collect most of the overdue money" he said.

But Wilson pointed at Johnson and retorted: "You've been saying that for the last three years.The fact of the matter is that you haven't collected it. If it's uncollectible, then say it's uncollectible and be through with it."

Johnson said that around one-fourth of the delinquent funds -- amounting to $2.5 million -- may never be collected. But he insisted that the rest of the delinquencies and all the current charges would be brought in.

The proposed increases, if approved by the Council, would go into effect when the 1981 fiscal year begins on Oct. 1. They are designed to bring in an additional $13.6 million, which would be spent primarily on improved sewage treatment at the Blue Plains facility, according to Edward M. Scott, chief of the revenue office of the environmental services agency.

Only five persons, including Johnson, testified at the hearing yesterday and just a handful of other residents came to listen. Wilson complained that residents would not show concern about the increases until "after the fact -- after they're already in place."

Although Wilson sharply questioned the increases, he predicted that his committee and the full council would eventually pass them. An increase would be the first in water and sewer rates since 1976.

They would raise water rates by 17 percent, from 39.4 cents per 100 cubic feet of water to 46 cents, and increase sewer rates by 51 percent, from 44.8 cents per 100 cubic feet of water to 67.7 cents. Taken together, the increases add up to 35 percent.

John T. O'Neill, executive vice president of the Apartment and Office Building Association, noted that by law, money from increased rates must be applied to water and sewer service and not to any other city programs. He said his group opposes the increases unless an audit is conducted and demonstrates that the funds are needed.

Estelle E. Sims, a Northeast Washington resident, said the proposed increases would create "a hardship for all." She complained about the department's erratic billing practices, which in recent years have meant that some customers have gone months or years without receiving a bill, and have then been forced to pay a large accumulated charge.