The Washington Post and a union representing its printers have reached tentative agreement on a new, five-year contract after almost two years of negotiations, Post and union officials said last night.

Leaders of the Columbia Typographical Union No. 101 agreed to recommend the package to members for ratification at a meeting Sunday, according to William Boarman, the union's president. The printers' old contract expired in September 1979.

Boarman declined to comment on the draft contract's terms until he had briefed union members.

But Larry Wallace, The Post's vice president for industrial relations, said the proposal would provide a retroactive raise of $30 a week for each of the two years since the expiration date of the old agreement. This raise would be paid in a lump sum. Then, Wallace said, each printer would receive an additional $35-a-week raise for each of the next three years and $33 for each of the final two years of the contract.

The Post's approximately 480 fulltime printers would be guaranteed jobs for life, a guarantee also included in the old agreement. But any printer who elected to resign would receive a payment of $25,000 to $35,000, depending on age, Wallace said.

Full-time printers would receive special bonuses of $500 each within one week of a contract being signed, Wallace said. This bonus would be in addition to all other monies.

"Productivity leave," a provision under which a printer took off three weeks a year in addition to four weeks' vacation, would be phased out altogether over a three-year period, according to Wallace.

Language concerning jurisdiction has been altered so as to give The Post "more flexibility" in processing editorial and advertising copy, Wallace said. "

"We feel the settlement, the proposed contract, is a good one," Wallace said last night. Agreement was reached on Wednesday night.

The tentative settlement was reached a week after The Post informed the union that it was canceling terms of the expired contract, under which the printers had been working while negotiations proceeded. That step opened the way for The Post to declare an impasse in the talks and enforce terms of employment based on its final offer, an option that the newspaper never invoked.