Photos of sewer gas sulphur odor leak discovery, cause, & repairs
Cast iron drain pipes in buildings
Diagnosing & repairing cast iron drain connection & leak problems
Diagnosing sewer gas odors traced to cast iron drain deterioration
Types of leaks occurring in cast iron drain piping
Life expectancy of cast iron drain piping
InspectAPedia offers impartial, unbiased advice without conflicts of interest.
We will block advertisements which we discover or readers inform us are associated with bad business practices,
false-advertising, or junk science. Our contact info is at
InspectAPedia.com/Contact.htm.
This article describes Conrad's experience in tracking down a sewer gas odor that appeared in the building's (transite) heating ducts, finding a leaky sewer pipe under the basement floor, and repairing cast iron plumbing drain waste vent piping, piping materials.
The articles at this website will answer most questions about water supply & drain piping, wells, & water tanks as well as many other building plumbing system inspection or defect topics. Reproduction of this web page electronically at other websites is prohibited.
Cast Iron Drain Pipe Leak & Repair Case - Odors Lead to Discovery of Under-Floor Drain Leaks
Cast Iron Drains Receiving Roof Gutter Drainage May Burst Basement Floor Slabs
Often on city lots that are flat and poorly drained, builders or building owners were pressed to decide how to get rid of rainwater spilling off of building roofs and through the gutter and downspout system.
The best approach is to route these drains to a nearby city storm drain, pumping if necessary but best by gravity. This avoids overloading the city sewer system during periods of heavy rainfall. Our photograph (left) shows a New York City storm drain overflow station (officially, a: New York State Wet Weather Discharge Point) where excess drainage is dumped into the Hudson River when more water or wastewater enters the city sewer system than can be handled. The green sign atop this drain warns
If you see a discharge during dry weather, please call 311 - DEP (Department of Environmental Protection).
Overloading a city's sewer often means that raw sewage is simply overflowed or dumped into local rivers or streams.
But It was common in previous generations for builders to rout (usually cast iron) drain pipes from ground-level outside of a building into the building, under the basement floor slab, and out to the municipal sewer system. These drains were used to receive roof gutter drainage and dispose of it into the city sewers.
Our photo (left) shows an in-basement cast iron drain line that originally received outside gutter/downspout drain water. At the time of our inspection that system had been changed and downspouts were routed to above-ground drains (unfortunately still too close to the building to assure a dry basement).
A problem with the in-building, under-floor piping disposal of roof runoff, besides overloading the city sewers in wet weather, is that eventually the under-floor drain may become clogged, perhaps with leaves washing into the drain from the building's gutters. The best result of that problem is that the drain stops draining and gutters spill outdoors along the foundation, perhaps leading to basement water entry, rot, mold, and insect damage.
Still more troubling, a blocked under-floor drain in a building left with no heat sometimes led to frozen drain pipes and burst, heaved piping and floor damage in the building, followed by an in-building flood when freezing weather changed to a thaw.
If you have roof gutters connected to drains that enter the building and are routed to the sewers, (a step still permitted and even required in a few communities), reconnecting the drains from outside ground-level to a nearby storm drain may be a better approach.
Leaky Cast Iron Drain Pipes Under a Floor Slab Send Sewer Gases into HVAC Ducts
A reader (Conrad) provided us with the photographs and case history of the successful track-down of sewer gas odors in a building (SEWER GAS ODORS). The case began with a complaint of sewer gas odors in the building's heating duct work system. As you can see from the "before" and "after" photos, this case involved the following combination of circumstances:
A transite heating duct was buried in a basement floor (below the slab) and located parallel to and immediately above a cast iron sewer pipe (photo below left)
The sewer pipe deteriorated and developed leaks (photo below right)
Sewer gases leaked out of the cast iron waste line and into the heating duct line.
The repair required breaking up the concrete floor slab and replacing the leaky sewer line. We recommended replacement of the transite heating duct as well.
The photo at below left shows the basement floor slab cut open to permit replacement of the leaky cast iron drain line. At below right our final photograph shows
the new white PVC drain piping installed in the floor.
Below we show the Sewer Line Break Repairs and floor re-tiled kindly sent along by reader Conrad.
Other water supply and drain piping and water pressure articles:
Pressure/Temperature Relief Valves, proper inspection methods, issues and hazards (article due in 2007)
Clearances Required for Wells Distance Between Well & Septic System and other water pollution sources, Online Table of Well Distances
FREEZE-PROOF PIPES: how to freeze-proof plumbing in a building, how to avoid freezing pipes, how to thaw frozen pipes: how to winterize a building against freezing and frost damage.
HOT WATER HEATERS - a detailed guide to all types of hot water sources, problems, inspection, repair
Tank Types Encyclopedia an encyclopedia of tanks in buildings, water tanks, fuel tanks, gas tanks, heating system expansion tanks, oil tanks, water cisterns, water pressure tanks, pressure booster tanks, antique, modern
Water Tanks - how to diagnose problems with water tanks, such as the need for air, how to add air, stop water pump short cycling to avoid damage - water storage water pressure tank safety.
Water Testing for contaminants in drinking water - what test are available, what tests to ask for, what they cost, how people cheat on water tests
Wells, Cisterns,& Springs types of sources of drinking water, what they look like, what goes wrong, what to do about it
WINTERIZE A BUILDING: how to freeze-proof plumbing in a building, how to avoid freezing pipes, how to thaw frozen pipes: how to winterize a building against freezing and frost damage.
Critique, contributions wanted: Contact Us to suggest corrections or additions to articles at this website, and if you wish, to receive online listing and credit as a contributor. Particular thanks are due to the many experts and also consumers who read and critique technical articles at InspectAPedia.com.
Additional technical contributors & reference sources for this article are listed below.
Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.
Thanks to reader Conrad for discussing an under-slab sewer gas odor source traced to a combination of transite heating ducts in the floor slab and leaky cast iron drain piping - January 2010
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.
The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 2010, $69.00 U.S., is available from Carson Dunlop. The Home Reference Book is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. InspectAPedia.com ® author/editor Daniel Friedman is a contributing author. Field inspection worksheets are included at the back of the volume.
Cheating on water tests: Testing Water for Real Estate Transactions - make sure your water test is valid
Mobile View
