Sink to Sewer 1/2" to 1-1/2" Drain Conversion Mod (Large Photos & Video)

Discussion in 'Plumbing Systems (The Fresh, The Blue, The Grey, &' started by Dubbya, Jul 6, 2012.

  1. Dubbya

    Dubbya Wherever you go, there you are...

    6,138
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    Aug 2, 2011
    Steinbach, MB
    Most (if not all) pups by Viking, Coachmen, Jayco, Dutchmen, Forest River and Rockwood, come with the standard sink drain and flexible hose that lead to a 3/4" fitting which sticks out of the exterior wall. It works, but if you actually use the sink and fill it up, it seems to take forever to drain, especially through 20 feet of 1/2" or 5/8" garden hose.

    It's not too big a deal for most folks but, since we seldom book a campsite that doesn't have full services, I despise having to use totes and aquatainers to collect gray water. The time wasted while waiting in a lineup at the dump station to empty them adds to the annoyance.

    Having seen a number of 1-1/2" drain mods, all of them seem to cover the exterior gray water plumbing. Unable to find even one tutorial or mod that clearly showed how to convert the sink itself and maintain a true 1-1/2" drain from the sink strainer to the sewer, I decided to make my own and thought I'd share with anyone else who might be interested in doing the same thing.

    I'm not going to provide all the costs or list all of the materials, as what's required is pretty self-evident as you review the photos I've provided. Other than the 1-1/2"x4" ABS threaded nipple and threaded ABS 1-1/2" pipe cap, anything you need is readily available and can be picked up at your local RV Dealer, online RV retailer and/or hardware store.

    Here are the tools you'll need:

    [​IMG]

    One of the critical and difficult to find components I needed was a waste overflow drain elbow. It fits the stock sink strainer which I already had. While the "Plug & Chain" waste overflow kit contained a few parts I wouldn't be using, it did have several of the parts I'd need anyway and it only cost $17.00.

    [​IMG]

    In addition, I picked up a 1-1/2"x 24' Sump Pump Drainage Hose Kit for $9.00. This kit contains the flexible hose, a hose clamp and threaded hose barb, all of which are required.

    [​IMG]

    Let's get started:

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    I was not able to find a 1-1/2"x4" threaded nipple at any of the local hardware stores but they can be ordered online through several plumbing supply websites.

    A 90 degree elbow fitting that came with 4" of thread and a threaded flange was perfect for this project and I picked it up for a ridiculous amount of money ($17) at a local RV dealer. A chop saw made short work of cutting off the threaded portion of the elbow. The same could be done with a hacksaw. Once the threaded section was cut, I removed the burrs and sanded the edges of the thread so they'd screw right into a female hub fitting.

    There are several options to making up this piece but I wanted to be sure I'd have plenty of thread sticking out the wall after I'd put the 1-1/2" electrical conduit locknuts and threaded flange in place.

    [​IMG]

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    The Automatic (Auto or Cheater) Vent performs the same task as the venting pipes included in other gray water drain mods, but this vent was actually made specifically for this application and I really like the nice clean hookup on the outside of the wall.

    You can pick up an Auto Vent in the plumbing dept at your local hardware store or online for between $6.00 and $8.00. Most are sold as carded items and assembly instructions are included.

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    The preceding hose end assembly is used at either end of the flexible sink drain hose and on the hose ends for the gray water drain hose. Hose sections can be added or removed as required.

    Although 1-1/2" ABS threaded pipe caps are available online, I was not able to find one at any of the local hardware stores. In the event that I have to use another aquatainer *Grrr!* I picked up a Valterra T01-0091V swivel drain fitting for $5.00 and added a 3/4" hose cap I had laying around to finish it off.

    When I was done, I rolled up my exterior gray water hose and stashed in a spiffy green bag I scavenged from the trunk in the DW's car.

    [​IMG]

    With that done, I ran a quick test without hooking up the exterior gray water hose as the pup was on my slanted driveway and I was only going to be expelling fresh water anyway.

    With the 1-1/2" drain installed, a full sink now drains in about 30 seconds.
    http://youtu.be/7XNhlO-zyt0
     
  2. cpd1343

    cpd1343 New Member

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    Oct 14, 2011
    Thanks so much for the EXCELLENT and well documented mod article. I already have a trap and have been looking for a way to get rid of it but could never find the 4" all thread plastic nipple needed! It never occurred to me to just cut off the existing one and reuse it.

    Thanks Again!
     
  3. Yellowkayak

    Yellowkayak Popups.....when sleeping on the ground gets to you

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    Mar 13, 2007
    Outstanding presentation on your mod...maybe RV manufacturers could learn a thing or two from you!

    JJ
     
  4. Dubbya

    Dubbya Wherever you go, there you are...

    6,138
    33
    Aug 2, 2011
    Steinbach, MB
    Those threaded nipples are indeed hard to locate and it's difficult to motivate a hardware store employee to order them in small quantities as well.

    That's why I paid dearly for that fancy threaded elbow they aold me at the RV dealership. They know too well that nobody else in town carries anything like that in ABS.

    Glad you found the post helpful!
     
  5. raymonk

    raymonk New Member

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    May 13, 2011
    Thanks, this is something that I need to do to my Viking pop up. Great information, presented well.
     
  6. Dubbya

    Dubbya Wherever you go, there you are...

    6,138
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    Aug 2, 2011
    Steinbach, MB
    Hah! Thanks, but I just snagged a few ideas from other drain mods, expanded on them and shared the information.

    Like so many members here, I'm all too happy if the ideas and information provided is of help to someone else, saves them some time, money and frustration.

    So many folks get overwhelmed and quit before even starting these projects. It's really a shame too, because all some of them need is a little help and encouragement to get started.

    I'm amazed at the number of simple, inexpensive and clever mods done by everyday folks and grateful for their willingness to share them with us here at the portal. The RV manufacturers could learn a lot from all of them! [PU] [MOD] [:D]
     
  7. PDieter

    PDieter Member

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    Aug 16, 2011
    nice job and great presentation for all of us.

    One thing...Paint that ABS. UV can destroy ABS pipe in almost no time at all.
     
  8. Dubbya

    Dubbya Wherever you go, there you are...

    6,138
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    Aug 2, 2011
    Steinbach, MB
    I did some research and according to a response from an ABS manufacturer that I read, UV damage is limited to between .001" and .003" from the exposed surface.

    That's the equivalent of surface oxidization in auto paint. Hardly seems worth worrying about, especially considering that the only exterior parts that would receive long term exposure would be the flange collar and the 90 degree swivel.
     
  9. PDieter

    PDieter Member

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    Aug 16, 2011
    It's just the feedback I get from my plumbing inspector. The crossed perception maybe between "UV Damage" and "if you don't paint that stuff it's going to get really brittle and shatter at the slightest impact"

    Untouched ABS exposed to UV may not suffer actual damage per se but become extremely susceptible to it. However I don't even play a product engineer on television so...
     
  10. Dubbya

    Dubbya Wherever you go, there you are...

    6,138
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    Aug 2, 2011
    Steinbach, MB
    Wonder if yours is another inspector with no actual experience who relies solely on the information provided in a typical field manual. They seem primarily interested ininsulating their @55e5 from litigation in the event that something they've inspected fails and is found to be the cause of personal injury or property damage.

    They're the reason the term "cost overrun" was invented.

    Seriously LOL'd @ "don't even play a Product Engineer on television"
     
  11. PDieter

    PDieter Member

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    Aug 16, 2011
    I really don't want to belabor the discussion but no he isn't and I don't think this is in a manual but gained from his experiences with broken pipes.

    I've seen pvc degrade by don't have experience with abs and uv. I searched pvc and confirmed my experience and then did a little abs.





    I'd paint it
     
  12. shelmily

    shelmily Well-Known Member

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    Jun 7, 2012
    Northeast Pennsylvania
    Hey Dubbya, In photo #30, is that just a piece of sch 40 pipe coming out of the elbow, and with a compression ring and nut? If not what did you use. I am going to attempt this mod this weekend. Man am I having a hard time finding ABS locally.
     
  13. rjniles

    rjniles Member

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    Aug 7, 2009
    Georgetown SC
    If ABS is not avaiable locally use PVC. They make the same fittings in both materials. The only problem I see is no trap. You can get sewer gas if connected to a sewer hookup.
     
  14. Dubbya

    Dubbya Wherever you go, there you are...

    6,138
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    Aug 2, 2011
    Steinbach, MB
    Photo #30?


    Painstakingly typed with very large fingers from my teenie, tiny iPhone.
     
  15. Dubbya

    Dubbya Wherever you go, there you are...

    6,138
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    Aug 2, 2011
    Steinbach, MB
    The beauty of using the hose as the trap is that it drains when you fold the galley over.

    It's just long enough to loop at the bottom when the galley is in place so there's no odor coming back from the sewer.


    Painstakingly typed with very large fingers from my teenie, tiny iPhone.
     
  16. Halford

    Halford Well-Known Member

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    Sep 28, 2011
    Santa Clarita, California
    I did a external mod on drainage. I will take pics of what it next time I go camping. It never slowed draining. Cost me around $15 dollars and only need a saw and measuring tape.
     
  17. shelmily

    shelmily Well-Known Member

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    Jun 7, 2012
    Northeast Pennsylvania
    Yes, the picture with the "30" in the circle in the upper left hand corner. It's the one where you are showing the end of the drain hose assembly where it attaches to the outside of the PUP. Don't tell me I am seeing things again. [LOL]
     
  18. Dubbya

    Dubbya Wherever you go, there you are...

    6,138
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    Aug 2, 2011
    Steinbach, MB
    Had to use Safari to see the photo as Tapatalk was hiding a bunch of images for some reason. Anyway,

    Sump hose to hose barb to threaded female hub to elbow to threaded swivel adapter which screws onto the threaded nipple sticking out the wall.

    There are several different ways to get there but this is what I did with the fittings that were available.


    Painstakingly typed with very large fingers from my teenie, tiny iPhone.
     
  19. shelmily

    shelmily Well-Known Member

    3,032
    99
    Jun 7, 2012
    Northeast Pennsylvania
    Thank you sir, that is exactly what I was wondering. A quick google search, and I have it and some other parts on the way.
     
  20. Dubbya

    Dubbya Wherever you go, there you are...

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    Aug 2, 2011
    Steinbach, MB
    Fantastic! Let us know how it turns out! Any other questions, just ask!


    Painstakingly typed with very large fingers from my teenie, tiny iPhone.
     

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