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 Galvanized Iron Water Supply Piping, & Galvanized Drain Piping
- Galvanized iron pipe inspection, diagnosis, repair
- Diagnosing & repairing clogged galvanized iron water supply pipes
- Diagnosing & repairing clogged galvanized iron drain pipes
- Black iron water piping
- Dielectric fittings to connect copper to galvanized iron piping - avoid corrosion
- Life expectancy of galvanized iron or galvanized steel water piping
- PIPE FREEZE-BURST PATTERNS - separate article
- Questions & Answers about galvanized iron pipes in buildings: clogs, leaks, repair, replacement of galvanized iron supply pipes or galvanized drain pipes
- References
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InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.
Galvanized supply or drain pipe troubleshooting: galvanized iron pipes in buildings: clogs, leaks, repair, replacement advice. Our page top photo illustrates galvanized iron (or some say "galvanized steel") water supply piping in home. This article lists in-depth references on inspecting, testing, and repairing problems with galvanized iron building plumbing: water supply and drain waste vent piping, piping materials, clogged or noisy pipes, and types of pipe hazards or product defects.
Green links show where you are. © Copyright 2013 InspectAPedia.com, All Rights Reserved. Author Daniel Friedman.
Galvanized Steel Water Supply Piping in buildings
 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. New York State License # 16000005303 (inception to 2008).
Galvanized steel (iron) is not commonly used as a water entry service pipe, although galvanized steel fittings may be found at the point of entry into the house.
Where galvanized service piping is used, it is typically at least 1 1/4-inch diameter. The word galvanized means zinc-coated. The coating helps prevent the steel from rusting.
Galvanized steel (iron) piping was common until roughly 1950. This piping typically lasts 40 to
60 years. Some lower-quality pipes do not last as long and there are some oversized pipes still in use after 60 years. Where it is found today in single-family homes, it is usually near the end of its life.
"Galvanized" refers to a metal plating process that coated iron or steel water pipe surfaces with a corrosion-resistant zinc surface.
Life expectancy of galvanized steel piping: Galvanized steel supply pipes
are typically 1/2-inch diameter. The connections are threaded. When the pipe corrodes, the rust accumulation inside the pipe chokes down the diameter of the pipe, resulting in poor water pressure.
Rust also attacks the pipe walls, making the walls thinner. Eventually, the pipe will rust through, usually at the joints first, resulting in leakage.
Galvanized iron water supply pipe can also burst from freezing, and may split at seams depending on how the pipe was manufactured.
Galvanized iron water supply (or drains) are more likely to burst by splitting or fracturing if pipe sections are corroded from an external cause such as corrosive water or by contact with materials or surfaces that increase the pipe corrosion rate.
Our photo (above left) illustrates a galvanized iron pipe failure (and replacement) at a spa in Lourdes, Mexico. |
Black Iron Piping in buildings
Uncommon for water supply piping but found as gas piping, oil piping, and some other uses, is black iron pipe - essentially the same material as galvanized iron piping, but without the protective galvanized zinc coating.
Diagnosing rusty galvanized steel piping
 As rust builds up inside the pipe, a brownish color is often noted in the water when a faucet is turned on, especially after several days of inactivity. This rust in the water usually dissipates after a few seconds.
As we mentioned in our discussion of lead water entry mains piping, many of the old lead service lines were connected to a galvanized nipple – a short piece of steel
pipe that was often in contact with the soil. This pipe rusts on the outside and inside, and may be close to the end of its life. It is often wise to replace this as a precautionary measure.
Galvanized steel piping will often leak first at the joints. Steel pipe has threads cut into it where
it joins a fitting. The pipe wall is thinner at the threaded connections. As the piping rusts from the inside, the pipe rusts through first at the threaded connections, where the pipe wall is thinner.
- Home Reference Book, used with permission.
Our photo (above-left) shows silver-colored water supply piping that is probably galvanized iron. But this pipe looks a little too good. We suspect from the photo that the pipe has been painted.
Watch out: because it's easy to spray-paint silver or aluminum paint on metal pipes in buildings, you may need to check closely or use a magnet to be sure that the silver-colored water supply piping you are examining is really galvanized iron (magnetic) and not painted brass (not magnetic) or painted black iron pipe (magnetic, paint scrapes off). Also, as our photo above demonstrates, don't miss nearby visually obvious safety hazards like the missing discharge tube on the pressure relief valve on that water heater! If someone spray painted brass water supply piping with aluminum paint you could be fooled. See BRASS WATER PIPES.
Galvanized to Copper Pipe Connections - Use a Dieelectric Fitting to Avoid Corrosion
 When connecting iron or galvanized iron pipes to copper in buildings, often corrosion and leaks will occur at the meeting of these two dissimilar metals.
Using a brass fitting to connect these two metals, or more commonly, using plastic or bronze fittings at the joint between these two metals will avoid future corrosion and leaks.
The photo (left) shows a galvanized iron union used to connect copper to galvanized iron. In the upper image you can just make out the black bronze ring built into this plumbing connector to avoid corrosion where the copper presses against the galvanized iron.
How do we explain that in some buildings we see direct copper-to-iron pipe connections with no corrosion? Luck? Maybe. But the corrosivity of the water is probably a factor in how rapidly copper-to-galvanized pipe connections will corrode and leak. Spelling note that may help some searches: it's not dialectic pipe fittings, but dielectric pipe fittings.
More about the galvanic scale and corrosion between dissimilar metals is at GALVANIC SCALE & METAL CORROSION.
Galvanized Steel Drain Piping in buildings
Our photographs (below) show galvanized drain piping in use in buildings. At below left, the cleanout in a galvanized drain line has been lost, plugged with who-knows-what, and is an odor and leak source. At below-right, the rope trying to secure the galvanized drain line to the cast iron sewer piping confirm a history of leak troubles and improper plumbing connections.
Clogged Galvanized Steel Plumbing Drains
When diagnosing clogged drain piping in a building (CLOGGED DRAIN DIAGNOSIS & REPAIR), an important distinction is between a specific point of clogging and piping that really needs total replacement. If a point-clog exists it can generally be cleared successfully. When mineral deposits or rust have decreased the interior diameter of galvanized iron pipe drains so that drainage is poor, plumbers use two methods to try to clear the lines:
- Snaking the galvanized drain pipe, sometimes euphemistically "running a wire" through the drains. We paid Plass the Plumber a stiff fee to provide this ineffective service in Poughkeepsie, leading to a big bill and no improvement in the piping. Eventually we opened the walls and cut open the drain line to see that only a very tiny internal diameter of drainage was left in a rust and mineral-clogged pipe.
- Using acid drain cleaners. This process might work if the drain pipes are not too badly clogged and if the steel or iron is otherwise in good condition. Beware of running acid into septic systems. (WHAT CAN GO INTO TOILETS & DRAINS?)
Other water supply and drain piping and water pressure articles:
- RELIEF VALVES - TP Valves on Boilers and RELIEF VALVES - Water Heaters and RELIEF VALVES - Water Tanks: proper inspection methods, issues and hazards of pressure & temperature relief valves
- Clearances Required for Wells Distance Between Well & Septic System and other water pollution sources, Online Table of Well Distances
- Clearances Required for Septic Systems Between Septic System & Wells, Streams, Trees, property boundaries, Online Tables of Septic Distances
- Clogged Drain Diagnosis: Is it a blocked drain or the septic system? - A First Step for Homeowners
- CROSS CONNECTIONS, PLUMBING - bacterial contamination of building piping - sources
- PLUMBING DRAIN NOISE DIAGNOSIS: may indicate defective or clogged plumbing: how to diagnose and cure drain sounds
- 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
- Life Expectancy of Water Pumps - Well Pumps: how long should a water pump last? What affects pump life?
- Life Expectancy of Wells & Water Tanks how long should a water well and its components last?
- Plastic Water Supply & Drain Piping Failures, Leaks, Repairs, Lawsuits: Water Supply Piping Defects and Plastic or polybutylene
- 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
- TANKLESS COILS for making domestic hot water
- Transite Pipe Water Supply Piping - what are the health hazards and other risks from cement asbestos (transite) water pipes?
- WATER HEATERS - a detailed guide to all types of hot water sources, problems, inspection, repair
- Water Pressure Adjustment how to adjust the water pressure in a building
- Water Pressure Loss - Diagnosis how to determine why water pressure has been lost or why there is no water at all in a building
- Water Pressure Tanks what they are for, how they work, what goes wrong, how to fix them
- Water Pump Pressure Control how to adjust the pump cut-on and cut-off pressures
- WATER PUMP SHORT CYCLING what to do if the water pump keeps turning on and off too rapidly
- Water Pump and Pressure Tank Diagnosis & Costs an specific case offers an example of diagnosis of loss of water pressure, loss of water, and analyzes the actual repair cost
- Water Requirements, Home & Outdoor Living
- WATER SHUTOFF VALVE LOCATION, USE how to find the main water shutoff and how to turn off the water in buildings
- Water Tank Air Charge how to fix a water tank that has lost its air charge
- 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
- WATER PRESSURE LOSS how to diagnose the cause of bad water pressure
- WATER PRESSURE BOOSTING how to install a system to increase water pressure at a building
- WATER TANK TYPES what are the types of water pressure tanks, how are they tested, maintained, repaired
- WELL CLEARANCE DISTANCES how far should the well be from the septic, road, property borders, buildings
- WELL, PUMP, TANK LIFE EXPECTANCY how long should a typical well, water pump, or water tank last?
- WELL PUMP PRIMING GUIDE how do we re-prime the well pump ?
- 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.
- Plumbing Links our big list of links to plastic piping and other plumbing defects
Frequently Asked Questions (FAQs) about galvanized iron plumbing pipes
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Technical Reviewers & References
Related Topics, found near the top of this page suggest articles closely related to this one.
- John Cranor is an ASHI member and a home inspector (The House Whisperer) is located in Glen Allen, VA 23060. He is also a contributor to InspectApedia.com in several technical areas such as plumbing and appliances (dryer vents). Contact Mr. Cranor at 804-747-7747 or by Email: johncranor@verizon.net
 Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. (416) 964-9415 1-800-268-7070 info@carsondunlop.com. The firm provides professional home inspection services & home inspection education & publications. Alan Carson is a past president of ASHI, the American Society of Home Inspectors. Thanks to Alan Carson and Bob Dunlop, for permission for InspectAPedia to use text excerpts from The Home Reference Book & illustrations from The Illustrated Home. Carson Dunlop Associates' provides:
- Commercial Building Inspection Courses - protocol ASTM Standard E 2018-08 for Property Condition Assessments
- Home Inspection Education Courses including home study & live classes at eleven colleges & universities.
- Home Inspection Education Home Study Courses - ASHI@Home Training 10-course program.
Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on these courses: Enter INSPECTAHITP in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
- The Home Reference Book, a reference & inspection report product for building owners & inspectors.
Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
- The Home Reference eBook, an electronic version for PCs, the iPad, iPhone, & Android smart phones.
Special Offer: For a 5% discount on any number of copies of the Home Reference eBook purchased as a single order. Enter inspectaehrb in the order payment page "Promo/Redemption" space.
- The Illustrated Home illustrates construction details and building components, a reference for owners & inspectors.
Special Offer: For a 5% discount on any number of copies of the Illustrated Home purchased as a single order Enter INSPECTAILL in the order payment page "Promo/Redemption" space.
- The Horizon Software System manages business operations,scheduling, & inspection report writing using Carson Dunlop's knowledge base & color images. The Horizon system runs on always-available cloud-based software for office computers, laptops, tablets, iPad, Android, & other smartphones.
- Mark Cramer Inspection Services Mark Cramer, Tampa Florida, Mr. Cramer is a past president of ASHI, the American Society of Home Inspectors and is a Florida home inspector and home inspection educator. Contact Mark Cramer at: 727-595-4211 mark@BestTampaInspector.com 11/06
- Roger Hankey is principal of Hankey and Brown home inspectors, Eden Prairie, MN. Mr. Hankey is a past chairman of the ASHI Standards Committee. Mr. Hankey has served in other ASHI professional and leadership roles. Contact Roger Hankey at: 952 829-0044 - rhankey@hankeyandbrown.com. Mr. Hankey is a frequent contributor to InspectAPedia.com.
- Arlene Puentes, an ASHI member and a licensed home inspector in Kingston, NY, and has served on ASHI national committees as well as HVASHI Chapter President. Ms. Puentes can be contacted at ap@octoberhome.com
- "The Fight Against Corrosion - A Study of the Nature of Corrosion and its Problems in Water Services and Heating Systems", Daniel Davies, Research and Development Services, Stansted Mountfichet, Essex, England, World Plumbing Conference-IV, "Plumbing and the World Environment, Compendium of Workshop Papers, October 3-6, 1996, Hyatt Regency Chicago, Chicago, IL", [personal correspondence, DJF - Author, July 2011]
- Water Pressure Loss - Diagnosis how to determine why water pressure has been lost or why there is no water at all in a building
- ...
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
 The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, 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. Field inspection worksheets are included at the back of the volume. Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
Or choose the The Home Reference eBook for PCs, Macs, Kindle, iPad, iPhone, or Android Smart Phones. Special Offer: For a 5% discount on any number of copies of the Home Reference eBook purchased as a single order. Enter INSPECTAEHRB in the order payment page "Promo/Redemption" space.
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