The most direct associations are to do with feelings of repulsion or disgust. The sewer is also an indication of what you have let go of as worn out, without life, or not needed in your living process of mind and body. It might also be associated with decay, disease or death. However, in modern mythology – films – the sewers are often shown as hidden ways to enter places or to escape, so might be used to suggest such in your dream.
In some powerful dreams the sewers are expressions of the wonder and strangeness of the subterranean world that is your unconscious. In this sense, the internal unconscious sewers were built by humans thousands of years ago. They are the level of awareness that at one time was mankind’s waking awareness. But as with the surface of the earth, further levels of growth covered and buried the old. Because these sewers are our psychological and spiritual history, you may find in them much that explains humanity’s, or your own, present condition. Some of what you find will be things you yourself left there in the far past. Exposing them and bringing what they reveal to awareness is a task many people are engaged in today. Some dreamer’s believe that the reason this level of the unconscious is shown as sewers, is because in the past humans acted as the means for tremendous cosmic forces to flow down into the earth. This faculty was desecrated and now what is represented as the sewers acts in man as the means by which, through which, destructive thoughts, energies, are released, lest they destroy humanity.
The strength you will find in exploring the sewers is that of being able to face the worst in human beings, and also to see within it what was once holy and divine. See Toilet.