| All fixtures in the home need to have a trap on them tubs and showers all have a trap Kitchen sinks have a trap and toilet bowls are traps, that's right toilet bowls are traps, the water in the toilet bowl works as a trap, that's why you don't need to install a trap under a toilet bowl, if you do install a trap under a toilet bowl, the toilet will not flush right, this is called having a double trap.
What is a P trap? Your basic trap that is shaped like a U or a J and goes into a wall is a P Trap, If you held it vertically with the part that goes in the wall on the bottom it would look like a P. (never understood that myself)
What is a S trap? A S trap is a trap that goes through the floor, This type of trap is not approved by the plumbing code because it is prone to siphoning it's self dry allowing sewer gasses to get past the trap.
I have a trap under my sink or tub or other and I still get a sewer smell in the fixture, why?
Something may be causing the trap to siphon dry, like a S trap or a clogged vent on the roof, The auto vents that you find under sinks or other places are not approved by code and do not allow enough air into the line for a drain to drain properly, causing a vacuum against the water in the trap, sucking the water out of it. If the vent on the roof is clogged (with birds or bees nests or leaves) and you flush a toilet, either the water in the toilet will just spin and not flush or it will siphon a trap dry, causing the sewer gasses to get into your home.
Many people think a plumbing vent is to vent the sewer odor from the sewer or septic tank,
This is not what a vent is for, A plumbing vent system is installed to balance the air pressure in the drainage and vent system, when water goes down a drain it pulls air down with it, the vents allow the air in to the system, so that the water can drain. with out the vents the drains can not work, and with improperly installed vents, traps will be sucked dry and cause an unsafe situation. |