Reuben's Home Inspection Blog


Illegal Plumbing Products in Minnesota

Home inspectors might find more hack repairs when it comes to plumbing projects than anything else - mostly because it's easy to  do a plumbing project wrong, but still have the drains work.   Sort of.

Drum Trap repaired with a coffee can bottom, tape, paint, string, and other stuff

I have about a million photos of hack plumbing repairs, but that's not the point of this post.  Today I'm going to give a list of some common plumbing products sold at home improvement stores and hardware stores in Minnesota that probably shouldn't be purchased.  Whatever you plan to do with these products is most likely going to be a violation of the Minnesota State Plumbing Code.


First and foremost comes my favorite; the drain tube meant for an S-trap or washing machine drain.  I love the photo below because the packaging encourages you to be your own plumber... which is exactly what the ambitious-looking square on the cover has decided to be, unfortunately.  He's installing an S-trap, which is illegal in Minnesota (4715.0960), and as far as I know, everywhere else in the country.  While the packaging also says that this 1-1/2" drain tube can be used for a washing machine drain, the minimum size allowed for a washing machine drain, also known as a standpipe, is 2" (4715.2300).

Be your own plumber
bottom note: what's with the suggestion to be your own plumber? Has this clever marketing piece ever actually encouraged someone to 'be their own plumber' ? By the time you've wandered in to the plumbing repair aisle at the home improvement store, there's a good chance that you've already made the decision to be your own plumber.

S-traps are usually found at sinks, and are often accompanied by several other plumbing defects.


There is no simple solution to an "S" trap, but they're usually not a major problem.

Bottle Traps

Another illegal plumbing trap is any type that relies on concealed partitions to create a trap - such as a bottle trap (4715.0960).  They come in several varieties.

Bottle Trap at store

Bottle trap in the wild

The proper and prudent product to purchase in these particular cases is a P-trap.

Corrugated / flexible traps

Corrugated drains have to be one of the most common 'handyman' plumbing repairs that home inspectors find.

Corrugated drain

Corrugated drain

These things violate a basic plumbing principal of the Minnesota State Plumbing Code - section F, which states

"F. The drainage system shall be designed, constructed, and maintained to conduct the waste water with velocities which will prevent fouling, deposition of solids, and clogging."  (4715.0200)

All of those little corrugations allow for fouling, deposition of solids, and clogging.  When changes in direction need to happen, it should be done with proper fittings that have smooth interiors.

Needle valves / saddle valves

Saddle valves are usually used for whole house humidifiers, which I'm not a fan of to start with, and ice-makers.  They work by piercing a hole in your water pipe, and they're prone to leaking.  They're also not allowed in Minnesota.

 Saddle Valve exploded

Instead of using a saddle valve, have a proper valve installed.

Clamshell toilet fill valves

Toilet fill valves are supposed to be installed with the critical level line at least 1" above the top of the overflow tube in the toilet tank.  One of the more common types of fill valves are the ones made by Fluidmaster.  The diagram below comes from their installation instructions, and it shows what a fill valve should look like.

The toilet fill valves that sit in the bottom of your toilet tank are often referred to as 'clamshell' fill valves, and they're not allowed in Minnesota, because they create a potential cross-connection between the water in the toilet tank and the potable water supply. Don't put these in.  See 4715.2150 - flush tanks.

Clamshell toilet fill valve

Instead of buying a 'clamshell' style fill valve, get the adjustable 400A valve made by Fluidmaster.  These are sold everywhere.

Rubber fittings

Rubber fittings used on drains or vents like the one shown below can sag or collapse.  They're always a no-no.

Rubber Elbow

If you can't figure out how to make your drains work without the use of rubber fittings, call a plumber.

The one exception to this for above-ground drain and vent piping is a rubber coupler with a stainless steel metal band or sleave surrounding it.  The stainless steel band gives it rigidity, which prevents what's happening to the un-banded connector in the photo below.

Collapsed rubber coupling

These un-banded couplers are sometimes allowed or even required on high-efficiency furnace vents, and they're allowed to be installed on their side when buried in dirt, but the other 99% of the ones you'll see are wrong.  The photo below shows a proper steel-banded connector.  Check out the fine print that says "2" CI, PL, or ST to 2" CI, PL, or ST".  This tells you the different materials that this connector is designed for.  These types of connectors are usually the right ones to buy.

Steel banded rubber coupling

Slang terms: Note the brand on the coupler shown above - "Fernco".  When you hear people refer to "Fernco" couplings, they're usually referring to couplings without metal bands, but Fernco obviously makes both.  When you hear people mention "Mission" couplings, they're usually referring to banded couplings... but Mission makes both as well.  For quick proof of this, do a google image search for "mission coupling", and do another for "fernco coupling".

Flexible connectors

Flexible connectors aren't allowed at water heaters or water softeners in Minnesota.  I've heard that these are actually a good thing to use in parts of the country that are subject to earthquakes, but not here.  The state plumbing code doesn't allow these flexible connectors, because they reduce the water pipe diameter - the minimum allowable pipe diameter is 3/4".  I know of one manufacturer that offers a connector with a .72" inside diameter, but they're still not allowed in Minnesota.

Water heater connector

Flexible water heater connectors

I have these connectors installed at my own water heater because that's what was there when I bought my house.  I could personally care less if they're there or not, because I've never noticed any difference in water flow at homes that have these... but they're still a plumbing code violation in Minnesota.

If you have a Truth-In-Sale of Housing Evaluation performed at your home in Minneapolis and the water heater is less than three years old, these flexible connectors would be a required repair item.

Mechanical vents

Mechanical vents are not allowed in Minnesota.  These are often referred to as cheater vents, and they come in two varieties - an air admittance valve and a check vent.  A discussion of the different types is a moot point for Minnesota, because neither is allowed.  If you're curious though, check out this post by Seattle Home Inspector Charles Buell on check vents vs. air admittance valves.

The photo below shows a check valve installed on a lav vent inside a cabinet.  On a proper installation, the vent would have been run inside the wall, connected to other vents for the bathroom, and eventually terminated above the roof.

Cheater Vent

The purpose of a mechanical vent is to allow drains to suck air without admitting sewer gas in to the home.  I've heard that air admittance valves actually work quite well, but they're still a code violation here in Minnesota.


Just because they sell it doesn't mean it's legal.  I often hear homeowners say "If these things aren't allowed in Minnesota, why'd the guy at the store sell it to me?"  The answer is usually that they didn't know any better.  You shouldn't expect the person working in the plumbing department at a home improvement store to be up-to-date on the latest plumbing codes.  Plumbers need a lot of training and experience - that's why they charge what they do.

Now go hug your plumber.

Reuben Saltzman, Structure Tech Home Inspections


Comment balloon 21 commentsReuben Saltzman • November 21 2012 02:34AM


First of all, that's the fabled Slanted S trap, invented on a ranch out west. 

Second, isn't a bottle trap okay when the compression fitting is behind the drywall?

Third, without corrugated plastic drains could not bend around things.  First things first.

Fourth, I've had a saddle valve serve my under-sink water filter arrangement for 14 years (really) and while I expect it to leak it is still there!

Fifth, the water in the toilet tank is still clean.  Taste it!

Sixth, rubber hoses make it possible to use Auto Radiator Leak to stop plumbing drains from leaking.  It is a cross-industry product.

Seventh, the metal band bladder allows for expansion and contraction.  Duh buddy.

Eighth, I thought the term "mission coupling" referred to something else entirely, but hey, the word Pro in Proflex says it all anyway and that's all you need to know.

Ninth, I am seeing flexible connectors more and more and there has to be a good reason for it.  You might want to back off on this one.

Tenth, you people are amazing.  What better place to hide the AAV but behind the towels?

Eleventh, I don't hug my plumber.  The guy never washes his hands.  His immune system must be kick butt.


Great post, as usual, Reubs.  Suggested, as usual, Reubs.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 6 years ago

By the way, Billy Jays is eyeing a couple of these products for future release.  Just thought you should know...

The guy is a predator.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 6 years ago

Ha!  Oh course, you're right on all counts.  As for those flexible connectors, I'm pretty sure the reason they're not allowed here might have something to do with a strong plumber's union ;).  Same thing with the AAVs.  

I always tell people to leave their saddle valves alone; as long as you don't touch 'em, they'll probably be fine.

Water in the toilet tank?  I just took you up on your suggestion... man, were you wrong.

I look forward to Billy Jays features :)

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) over 6 years ago

Billy has a product out just today!  And as to the toilet tank water, well, sometimes discretion is the better part of valor.

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 6 years ago

Jay - about the toilet tank water... you tell me now.

Valerie - you're certainly right about that.

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) over 6 years ago

So many issues, how can a homebuyer ever know that these things are a problem??? Oh, I remember, call a home inspector before he buys the house. nice post.

Posted by Scott Seaton Jr. Bourbonnais Kankakee IL Home Inspector, The Home Inspector With a Heart! (SLS Home Inspections-Bradley Bourbonnais Kankakee Manteno) over 6 years ago

Very interesting information for non-plumbers!  I love the first picture with the coffee can and string.  MacGyver was there?

As for tasting toilet tank water, Ewwwwww. 

Posted by Kat Palmiotti, The House Kat (Grand Lux Realty, Monroe NY, 914-419-0270, over 6 years ago

I was hoping he'd save that water for Thanksgiving Kat.  Honestly, I don't know why he tasted it today...

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 6 years ago

Reuben, Love the drum trap by Folgers. We allow both the Flex line and AAV out here.

Have a very Happy T-day

Posted by Donald Hester, NCW Home Inspections, LLC (NCW Home Inspections, LLC) over 6 years ago

Boy you guys are tough in Minnesota. Love the "S" trap. 

Posted by James Quarello, Connecticut Home Inspector (JRV Home Inspection Services, LLC) over 6 years ago

Scott - bingo!

Kat - that was definitely a MacGyver style drum trap repair.  Hey, at least it wasn't toilet bowl water ;-)

Jay - I'm never listening to you again.

Donald - the Folgers drum trap.  Ha!  We should allow those flex lines and AAVs out here as well...

James - the worst, aren't we?  That's what you get with a homegrown plumbing code.

Posted by Reuben Saltzman, Delivering the Unbiased Truth. (Structure Tech Home Inspections) over 6 years ago

And people wonder why they have issues at times.  I understand cost, but that is also why many people should not own a house!

Posted by William Feela, Realtor, Whispering Pines Realty 651-674-5999 No. (WHISPERING PINES REALTY) over 6 years ago

Do a good turn daily, help old ladies across the street, be prepared and think to be physically strong, mentally awake and morally straight.

And avoid toilet water of any ilk, except perhaps when your wife is wearing some.  She will appreciate the compliment.

Go ahead and defy any of that!

Posted by Jay Markanich, Home Inspector - servicing all Northern Virginia (Jay Markanich Real Estate Inspections, LLC) over 6 years ago

Reuben- I guess this is an example of just because it's sold at a hardware store doesn't necessarily mean it's ok to use it.  

Posted by Kathy Streib, Home Stager - Palm Beach County,FL -561-914-6224 (Room Service Home Staging) over 6 years ago

I saw your featured post from kathy and had to stop by....glad I did! Enjoy your day :)

Posted by Kristin Johnston - REALTOR®, Giving Back With Each Home Sold! (RE/MAX Realty Center ) over 6 years ago

Good morning Reuben,

I missed this post but picked it up in Kathy's post his morning on her Ah-ha moments for the week. She was definitely right about your post! Wow just because it isw sold doesn't make it right!! I just can't imagine some of these working..excellent post as always!


Posted by Dorie Dillard CRS GRI ABR, Serving Buyers & Sellers in NW Austin Real Estate (Coldwell Banker United Realtors® ~ 512.750.6899) over 6 years ago

Wow, Reuben, I've been in construction forever and I havent even seen some of those things.  A few looked a little scary.  I can only see water everywhere. 

Posted by Mike Cooper, GRI, Your Neighborhood Real Estate Sales Pro (Cornerstone Business Group Inc) over 6 years ago

Posted by Kathy Streib, Home Stager - Palm Beach County,FL -561-914-6224 (Room Service Home Staging) over 6 years ago

You have really found some doozies! I can't believe my eyes on some of the hack jobs here.

Posted by Nan Jester, Realtor, Exit Real Estate Gallery (Exit Real Estate Gallery Jacksonville Beach, FL ) over 6 years ago


Wow.  How can so many incorrect types of repair devices be available for sale?  My advice, call a plumber, I sure would.

Posted by Evelyn Kennedy, Alameda, Real Estate, Alameda, CA (Alain Pinel Realtors) over 6 years ago

Thank you, Ruben.  Sounds as if, with the strict and prolific rules there in Minnesota, the consumers are quite lucky to have someone so thoroughly knowledgeable as you.  I certainly learned a lot.  You could write a book!  (Oh, wait.  You did.)

Posted by Lee Alley, DIY Your Own Expert Smartphone Photography (Pro Mobile Photo) over 6 years ago