Plumbing in the Home/Air Vent on Sewage Line.


We have an Italian style house (11" concrete walls) with a tile roof built in 1927 2 1/2 program.  We lived here from 1980 to 2007 with no plumbing issues.

In 2007, we had a plumbing leak in a 1/2 bath on 1st floor, and while fixing that leak, we were told one of the fittings on that line "was in wrong (upside down) and needed to be reversed".

After that change, all of our drains, sinks, toilets "bubble" whenever one toilet is flushed and whenever the upstairs washing machine empties.  Additionally, from that point on, we continuously have noticed sewage smell from over the kitchen drain and in other sinks 1st floor sinks.   

Yesterday, a plumber here for an unrelated problem told us that the cause is that there is no fresh air vent on the sewer line.

1.  Is this possible?  
We didn't notice any issue until 2007.  All the plumbing systems passed a building inspection in 1985 when we did a major addition and renovated all bathrooms and kitchen plumbing and moved the laundry upstairs. Wouldn't something that critical (one of your posts said this is the most critical issue with plumbing systems) have been part of the inspections/permits?

2. If there originally was a fresh air intake, what would cause these types of problems to appear only after 2007?
We noticed this issue immediately when the plumber left so it didn't develop over time.  Since the problems only appeared relatively recently, is it possible that the change made in 2007 might have disconnected that line an existing fresh air intake?

We noticed that we have two pipes coming out through our existing tile roof and they are 5 feet away from chimney/heater exhaust stacks.  Because we have no forced air heat systems - all radiators), might those be air intakes for the sewer line?   

3.  Because we are dealing with concrete walls and Spanish tile roofing, putting any new vent or piping through the outside walls  is a major issue for structural as well as aesthetic reasons.

a.  Would you recommend tracing those roof stacks through the house to see they were fresh air intakes that have been disconnected?

b.  If that is not possible, is venting into the house through a filter made for indoor air intact safe, e.g., venting into the basement?  Or Does it have to be vented through the highest point in the house?

Susan, First of all, who ever told you that the venting of a plumbing system is the most crucial aspect of a system, is ABSOLUTELY correct. I can not stress enough the fact that venting makes it all work.
Whatever the person did in 2007 either plugged the vent or disconnected it or rendered it inoperable somehow. I would definitely recommend tracing the lines if possible, but most are usually inside the walls. Yours may be different due to the concrete construction.

All the localities that require a plumbing code be followed, use the ASPE(American Society of Plumbing Engineers) standards. These standards call out, among hundreds of other requirements, the size of piping required for drains vents and stacks. Almost always, a minimum 3" vent pipe is required for all systems that have at least one toilet on it. And it must be vented to the outside above the highest window  or opening. Almost always above the roof eve.
It would be very rare and impossible for you to not have trouble from the day the house was built if there was no vent. If you can positively identify the vent on the roof, you could have rod the line from the roof to see if there is an obstruction. Sometime a garden hose is used but if the line is disconnected, you may have water in the house and cause a new problem.
I would call a reputable plumber, explain the issue and have them investigate. This is not a job for a"handyman"
Lastly, under no  circumstances can sewer gas be vented indoors. Sewer gas contains methane gas, it is highly flammable and toxic. It must be vented to the atmosphere, no filtering or exceptions.

Plumbing in the Home

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Jay Nicholas


Plumbing & Heating (warm air, hot water & steam heat)


40 years in the business, 35 years as a lic. master plumber in NY State. Retired

Graduated Magna cum laude at the School of Hard Knocks

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Commercial, residential and light industrial. You name it ...I have probably worked on it

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