A typical District of Columbia household faces a water and sewer bill that will be $40 higher during the 12-month period starting Oct. 1, the head of the city's Department of Environmental Services said yesterday.

Departmental director William B. Johnson said the higher fees are necessary to pay for higher operating costs and a long-deferred program of replacing ancient water mains that regularly burst, and to provide funds so the agency can respond faster to complaints of clogged sewer pipes that often spill their nauseous contents back into peoples' homes.

For a typical four-person Washington household, Johnson told the House D.C. appropriations subcommittee, the annual combined water and sewer cost will rise about 30 percent, or from about $120 to $160. Bills are sent for half the amount twice a year.

Compared with recent higher water- and sewer-rate increases in the suburbs, "we believe that 30 percent is a modest increase," Johnson testified. s

The subcommittee is holding hearings on the city's budget for the 1982 fiscal year, which starts Oct. 1, the date Johnson said he plans to put the new water and sewer rates into effect. He said no further action by the D.C. City Council is needed.

The city currently charges 46 cents for each 100 cubic feet of water -- about 748 gallons -- delivered to customers, and 67.7 cents for each 100 cubic feet of sewage collected and treated, a combined total of just under $1.14. A 30 percent rise would push the total to nearly $1.48 for each 200 cubic feet.

The water- and sewer-rate increases were included in the budget proposed last fall by Mayor Marion Barry. For homeowners, they will come on top of a typical $165 increase in real estate tax bills that are expected to result from an average 21 percent increase in property assessments, assuming continuation of the current residential tax rate of $1.22 per $100 assessed valuation.

Johnson testified that his department has collected $5.5 million of the $10 million in water bills that were delinquent in the spring of 1980. The collections are a result of an accelerated drive that included the resumption of service that was cut off for seriously overdue customers.

Johnson asked the congressional panel to approve nearly $10 million in spending that, among other things, would permit the replacement of old water mains throughout the city, one-third of which were installed between 1850 and 1900. He blamed these pipes for many of the well-publicized water line breaks in the city in recent years, including one on Jan. 27 that routed residents of a Southeast Washington apartment complex in the middle of the night. His proposed budget also would permit crews to work on an overtime-pay basis to repair sewer lines that break at night and on weekends.

Johnson told the congressional subcommittee that the budget will require him to abolish his department's separate noise-control program, but that two employes now assigned to that program will be available to deal with specific public complaints about violations of the city noise law.