Mommy, Why Does the Basement Smell Like a Sewer?
Well, Dear, it’s like this: You haven’t been flushing the drain on a Bi-Monthly basis as I had instructed you. What part of “Flush Drain” don’t you understand? . . . . Uh, how do you know what a sewer smells like?
You may have noticed that all drains have a goose neck under the basin. Many people say the goose neck is to catch things that might plug up the sewer system. Often, these really don’t catch things that can escape the narrow openings of the drain nets. So what are they there for?
Because of the drop in the neck (thus creating a “goose neck”), water is trapped in that area. Why would we want to trap water in a goose neck? Well, water is an excellent insulation against smell. The place that drain pipes lead to is the sewer. If we didn’t trap water in goose necks, we would be continually getting the interesting smells of the sewer.
It doesn’t usually show, but basement drains also have goose necks buried in the concrete. A diagram of a basement drain is shown in Figure 1. Note how water is trapped in the bowl whose upper limit is the ridge under the concrete before it dips downward. This is to prevent the sewer aromas from getting into the basement rooms.
Many basement drains are seldom used. After a while, the water in the trapped bowl of unused basement drains evaporates. When the water drops below the inner elbow of the goose neck due to evaporation, then the sewer vapors begin to escape into the room. A person living in a house where odors gradually build up usually don’t notice the insidious arrival of those odors. Others who come to visit will recognize them, but won’t say anything, so as to not hurt any feelings. A good “basement drain flush” on occasion will keep the bowl full, and the basement won’t smell like a sewer. By doing this, you can cut down on your air freshener.
A toilet also has a gooseneck, hidden within the porcelain walls of its base (See Fig. 2). This is why we always see a little puddle of water at the bottom. The presence of the water is an ingenious contrivance to not only block sewer smells, but to provide an easily cleanable surface for anything that might tend to “discolor” the inner surface of the bowl.
Well, you are now armed with another answer to a “Mommy, why” question.