Odors cause customers and staff to cringe. Odors can be very hard to find. With differing pressures of air and water moving through the drains and rooms odors can shift direction or become intermittent making it extremely hard to find.  So the question is “How is an odor located and resolved”?

Ptrap odor

To solve odor problems they first need to be identified, labeled and understood in order to be solved.  It takes experience to know the difference between sewage, grease, musty, stagnate, mildew, throw-up and other types of odors. If you are not familiar with each smells you can still locate and make repairs. The following are hints to recognize the most common odors and make repairs.

clean out odor

Sewage: Sewage is a bitter smell and can be confused with a grease trap smell, or vice versa. Once you have been around these two odors enough you will be able to distinguish between them. Sewage smells come from drain lines that release sewage gas into a restaurant or room. The following are areas to inspect to determine the source of a sewage leak:

studor vent odor
  • Inspect all floor sinks & drains making sure they have standing water in the P-Trap. P-traps are designed to hold water making a “water seal” which blocks odors and bugs from passing through. When a P-Trap is broken it will leak and lose its water in the trap allowing gases/odors and/or bugs to pass through. If this happens the P-trap will need to be replaced.  If a P-trap is not used for a long period of time the water seal will evaporate, the easy solution hear is to fill the p-trap back up with water.
  • Inspect all cleanouts. Cleanouts have service plug screwed into the drainage pipe under the clean out cover. The plug needs to be without flaw/holes preventing gases to exit. If the plug is damaged even the smallest blemish will cause a significant odor
  • Inspect wax rings on all toilets as they can emit odors when not seated properly.
  • Inspect above ceiling line for any opened/abandon vent pipes. Vent pipes or cracked drainage pipes will cause odors to escape.
  • Validate vents lines on roof are higher than the parapet wall to allow odors to be swept away with the breeze/wind. HVAC units near vent pipes can pull odors into the building. A solution for this will be to install a charcoal filters on the roof vent pipe.

If you are having a hard time locating a sewage odor a plumber can perform a smoke test to locate any breaks in plumbing and/or vent line system. Make sure when doing a smoke test the plumber uses a high powered smoke machine and not a smoke bomb (large amount of smoke is needed). It is also best to perform a smoke test at night or early morning with low light & flashlights. The lower the light the better to see the white smoke emerge. A laser light/beam can be very helpful reflecting and identifying smoke

Grease Trap Odor: Many confuse a grease trap odor with sewage even though they are 2 different odors: The following are hints to locate a grease trap odor and stop it.

smoke test plumbing odor
  • Inspect the cleanouts on the inlet and outlet of the in ground grease trap. A cleanout will have a service plug screwed into the drainage pipe below the finished cover. Validate the service plugs are without flaw/holes and are secured in place preventing odors from exiting. If the plug is damaged even the smallest blemish will cause a significant odor
  • Inspect grease trap covers validating they have no holes in the metal trap lid that can let odors out. The trap lid should say “interceptor”. If the trap lid still emits gas applying a thin coat of silicone around the trap lid helps stop gases from exiting through the perimeter. Another option would be to install a “trap Hat”. A “Trap Hat” is a giant disk that slips under the trap lid, like an oversized clean out service plug, to keep odors from rising.
  • Validate that the grease trap rings that hold the trap lids in place are securely mounted to the grease trap basin with not cracks or breaks. Grease traps that are located in the planters/dirt sometimes are set in a hurry and not sealed tightly to the trap basin allowing odors to seep out.

Indoor Odors: In door orders can be a mixture of grease trap gas, sewage gas, mildew, throw-up, stagnant water smell or more: While already addressed how to locate grease and sewage odors, let’s look at some other nuisance odors:

vent outdoors.jpg
  • Throw-up Odor: A throw up odor can be coming from damaged syrup lines that have leaked and dried up. The solution is to fix the leak and clean up the syrup, which typically found in the underground soda chase.
  • Stagnant Odor:  Stagnant odor can be from
  1. Water sitting under damaged and delaminated tile,
  2. Between the cove base tile and wall,
  3. Plumbing line leaking within a wall or cabinet,
  4. Soda/beer chase line filled with water
  • Mildew Odor: Mildew odor is relatively easy to find as it is also visual at the area the odor is smelled. Mildew can be caused by mold developing in a wall or cabinet where water can slowly collect.

Outdoor Odors: Outdoor orders can be grease line gas, natural gas or stagnant odors. While we already addressed how to locate grease odors, let’s look at some other nuisance odors:

  • Natural Gas: Natural gas can be from in ground patio heaters that have rusted and allowing natural gas to escape. This will require immediate repair by a plumber.
  • Stagnant Odor: Patio drains typically do not have p-traps. This is due to the risk of having water freeze in the trap causing the P-trap to break leading to costly repairs.  With the patio drains not having p-traps debris and sludge can get caught in the pipe causing the odor to escape into the patio. In addition the drain line will be tied to a mainline and that odor can also escape into the patio. A solution for patio drains is to install a one-way valve plug. Be careful when using these as they can be pushed further into the drain causing future blockage and problems. It is not recommended using the one way valves in a floor sink or drain for this exact reason; however, use in a patio drain is low risk.

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