The president of a Beltsville firm involved in allegations of bid rigging and price fixing on contracts to build sewer and water lines in the Maryland suburbs was sentenced to 30 days in jail yesterday for filing false information on a state income-tax return.

Marvin Bosley, president of Suburban Utility Contractors Inc., had pleaded guilty and was sentenced to one year in jail, but Prince George's County Circuit Court Judge Robert K. Woods suspended all but 30 days, ruling that Bosley would serve his terms on a work-release basis.

Bosley also was ordered to perform 200 hours of community service, correct his income tax returns from 1977 through 1980, pay interest and penalties due as a result of filing the incorrect information, and pay $50 in court costs. Woods also placed Bosley on probation for three years.

The charge against Bosley came after an investigation by the attorney general's office, sparked by a series of articles in The Washington Post in August 1980. The Post reported that five local contractors, including Bosley's company, had cooperated in bidding on Washington Suburban Sanitary Commission contracts for connecting new homes to existing sewer and water lines.

After the stories appeared, the WSSC, which builds and maintains water and sewer lines in Prince George's and Montgomery counties, revamped its contract-letting procedures.