The Washington Suburban Sanitary Commission is considering putting locks on sewer vents and pipes in order to prevent a recurrence of last week's accident in Takoma Park in which a delivery man accidentally pumped 2,000 gallons of gasoline into the city sewerage system, causing 12 explosions and forcing the evacuation of a 15-block area.

Locks are one of several measures the commission members will consider in January, according to commission spokeswoman Marjorie Johnson.

The commission is particularly concerned, she said, because a similar error occurred last summer, damaging nothing except several manhole covers.

A new system of marking sewer outlets "would not totally preclude" dangerous substances entering the sewerage system, Johnson said. Somebody could accidentally flush flammable liquids down a toilet, she noted. But signs or locks could prevent large-scale errors like the one that, according to city fire officials, led a transport company employe to mistakenly identify sewer pipes for an underground gasoline storage tank.

The commission and Takoma Park officials are still figuring the costs of cleaning up the accident. City officials said yesterday they have not decided whether to recover costs through legal action.

The American Red Cross is still looking after four families displaced by Thursday's explosions.The families are in motels and looking for homes to rent, according to Red Cross officials.