Old Floor Drain No Trap

In the short term try 5 10 bleach solution in water not just water.

Old floor drain no trap.

The main problem. The drain pipe dips down in a u that is always filled with water whether flowing or still. The traps used in floor drains are like those used under kitchen and bathroom fixtures. The shaded portion shows the trap where water will always sit which prevents sewer gas from coming in.

The drain trap is an important part of the floor drain. That would allow sewer gas to come up through the drain into the room. Many older houses in minneapolis and saint paul have an old style of plumbing trap called a drum trap which is no longer allowed in minnesota except in special circumstances. As water drains down the steep slope at the wye it can create a siphon effect such that water will be sucked out of the trap.

Solve that problem just by dumping a pitcherful of water into the drain to restore the trap water. A cup of bleach to a gallon of water 1 15 or about 6 7 it may be a floor drain to soakaway rather than connected to septic sewer but those can still get quite nasty especially if something crawls down there and dies. Water in any trap under unused drains will eventually evaporate. Floor drains are most often installed during original construction often in the utility area to drain away excess water in the basement.

Floor drains are no exception. Many basement floor drains tie directly to the home s sewer system but in some communities local building codes require floor drains to run to a sump pit where a pump lifts the water to the exterior surface of the house. You have a water trap under a floor drain laundry tub or wash basin that has dried out from lack of use. The photo at right shows a floor drain as viewed from the side.

Connecting a trap to a vertical drain with a wye fitting and a 45 degree elbow seems like a good idea. The water filled trap prevents noxious sewer gases from backing up into the home.