The well-made and properly mounted plumbing system is odor-free. In most cases, odors come up from leaks in the waste or vent piping or from traps that have lost their hydraulic gate. In an improperly mounted system, there are, of course, a lot of chances for odors to arise resulting from faults in the system, especially if it is not appropriately vented.
In any case, atypical odors shouldn’t be ignored. These odors are usually a sign that sewer gas is there. Sewer gas is not always deadly; however it is poisonous and may cause headaches and other minor diseases. Sewer gas is polluted smelling air and it should be deterred from getting into the house.
If you suppose that sewer gas is coming through the leak in the piping, the plumbing system must undergo a test either using smoke, water or oil of peppermint. The test will point to the leak location.
In order to explicate how the sewer gas can get into the house through a plumbing fixture, it is essential to explain the function of traps and vents. Each plumbing fixture is the terminus of the city water supply system and the start of the city sewerage system.
The taps manage the water supply. The traps and vents manage the sewer air. They perform that by a very plain means. Sewer air won’t go through a water obstruction.
Thus, an appliance is used that keeps a few inches of water between the home air and the sewer air. That is the trap that is clearly observable under the plumbing fixtures, like sinks and toilets. It is usually built in water closets. When the bathtubs and shower cabinets are present, the trap is frequently hidden in the floor or basement.
Nevertheless, a trap might lose its hydraulic gate by siphon action each time a fixture is applied till the air on the sewer side is balanced with the home side air. That is the vent’s function. From time to time, because of the changes in atmospheric conditions, an efficiently vented trap will lose its seal.
As a rule, when a trap loses its seal, that is because of wrong vents design, absence of vents or evaporation of the trap water. Traps under fixtures, which are used only occasionally must be filled with water periodically to assure a sufficient trap seal.
| 
