Seattle Home Inspector's Blog


Dead Legs---illness waiting to happen?

dead legsA dead leg is any part of your house water supply where water cannot circulate. They are most common in extensions to the plumbing system for future use. For example when the house is built, plumbing is installed for a future bar sink in the basement. Over the life of the home, as those pipes sit full of water—not circulating with the rest of the house water supply—there is a risk of bacteria growing in the pipes. The same can happen with bathrooms that are not used very often.

Circulating loops, especially on the hot water supply side is one way to avoid this stagnation of water in the pipes but honestly there is no real easy answer to the problem. When you consider that a dead leg is considered anything more than 2 pipe diameters away from the flow of water, it does not take very much to create a pocket of water where water can stagnate. Contaminated watering holes come to mind.

There are increasing numbers of Legionella cases being blamed on Dead Legs and the number of actual illnesses is likely much higher, with many cases of flu-like symptoms going unreported or undiagnosed.

Recommendations for how homeowners should deal with water in seldom used sections of piping is evolving, but certainly any sections that are intended for future use should be properly isolated from the house system until such time as the installation can be completed.

For further information: Promoting Water Quality and Hygiene


By Charles Buell, Real Estate Inspections in Seattle

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Comment balloon 8 commentsCharles Buell • July 05 2015 01:20PM


never even thought about that before. We rarely use our second bath now that the kids are gone. I guess I should do that more often.

Posted by Tammy Lankford,, Broker GA Lake Sinclair/Eatonton/Milledgeville (Lane Realty Eatonton, GA Lake Sinclair, Milledgeville, 706-485-9668) over 2 years ago

Thank you CHarles -  I never realized this existed, but makes perfect sense.

Posted by Gay E. Rosen, As Real as Real Estate Gets! (Julia B. Fee Sotheby's International Realty) over 2 years ago

Not to mention corrosion and the possibility of future leakage.

They have really decorated up those pipes in the pic 

Posted by Fred Hernden, Albuquerque area Home Inspector (Superior Home Inspections - Greater Albuquerque Area) over 2 years ago

So can a homeowner just put a cap on the pipe so that any toxicity coming from the line can't escape in to the home?

Posted by Nicole Doty - Gilbert Real Estate Expert, Broker/Owner of Zion Realty (Zion Realty) over 2 years ago

Interesting.  I need to check out a couple of old piping sites I have and change this.

Posted by William Feela, Realtor, Whispering Pines Realty 651-674-5999 No. (WHISPERING PINES REALTY) over 2 years ago

Charlie, Nice article. You old dead legger you ;)

Posted by Donald Hester, NCW Home Inspections, LLC (NCW Home Inspections, LLC) over 2 years ago

Tammy, I wish I knew what the answer was but I do think that frequent circulation of the water is a good idea

Gay, while it makes sense, it is something that will be hard to fix entirely in the average house

Fred, yes---a little excess wire for future use---that too should be properly terminated

Nicole, the risk is that bacteria growing in the unused pipeing will migrate to the piping that is being used so capping will not help but disconnecting the piping from the system will.

William, let us know how you do with it.

Don, from dead head to dead leg I guess.

Posted by Charles Buell, Seattle Home Inspector (Charles Buell Inspections Inc.) over 2 years ago

I have never heard these referred to as dead legs before.

But your point is taken.  One of the things they did to me in Houston was to remove my LAA (Lateral Atrial Appendage).  That is a dead leg on the heart where blood collects, does not flow out so easily, and where 90+% of clots occur that cause strokes.  They staple it off and remove it.  I have a photo of mine!  Want to see it? 

Removing the dead leg reduces my chance of ever having a stroke by more than 90%.

So my plumbing will not have any of the dead leg problems you refer to in your post.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 2 years ago