Dewatering a toilet with a shop vac

Discussion in 'Toilet Forum discussions' started by alternety, Jan 22, 2012.

  1. alternety

    alternety Like an engineer

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    I am removing a toilet and have noted in a number of posts that you should use a shop vac to get the water out of the trap.

    I am probably being overly cautious, but that seems like a bad idea. Many motors have brushes and make sparks. This process will be drawing methane through the shop vac and over the motor (they do this for cooling). It could go bang.

    I will use the blow side of the shop vac to force water out.

    Just a thought.
  2. Terry

    Terry Administrator Staff Member

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    What!?!

    We use wet vacs every day to "suck" water out.

    And we're still here. Methane gas being a danger during a toilet replacement? That's a new one.

    stinger_wet_vac.jpg
    Last edited: Jan 22, 2012
  3. cacher_chick

    cacher_chick Test, Don't Guess!

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    Blow into the bowl?

    If you want a toilet water shower, I highly recommend it. :D
  4. Terry

    Terry Administrator Staff Member

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    I hadn't even though of that. Good point.
  5. Hackney plumbing

    Hackney plumbing Homeowner

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    You will not get water in the shower if you blow water out the bowl if the toilets vented.
  6. BobL43

    BobL43 DIY Senior Member

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    no, but you may get in your face blowing out of the toilet bowl. yummy: NOT!
  7. johnjh2o1

    johnjh2o1 Plumbing Contractor for 49 years

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  8. alternety

    alternety Like an engineer

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    I am assuming people using the exhaust to empty the trap will be astute enough to pack around the air hose. If it is a properly vented system, nothing else is going to happen. I will let you know.

    I did effectively say it is a low probability that you will be blown out of the bathroom riddled with shrapnel. This sort of thing has happened in surgery when bowels are opened. In a worst case situation (probably septic systems), it is functionally equivalent to defeating the pilot/ignition and turning on the gas to a burner and then using a shop vac to clean off the burner. You will live or die based on factors such as the type of motor in the vac and how long you do it. And perhaps random chance. I have been trained to examine failure modes and avoid them rather than rolling the dice. It is an engineering thing. Which is similar to saying it is a paranoid thing.
  9. Terry

    Terry Administrator Staff Member

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    Remember that these are "Wet Vac's"

    They engineer these things to be used for sucking up water. And we believe them. It's been working for years perfectly that way.
    If there was a rash of people dying from using "wet vacs" to vacuum water, I'm sure it would have made the news.
  10. dlarrivee

    dlarrivee New Member

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    You're crazy OP.

    Why would they call it a "wet-vac" if it was going to electrocute you when sucking up water?

    I use a plunger to push as much down the drain as possible, then I use this guy:

    [​IMG]

    Cheap like borsch, fits on a 5gallon bucket, and sucks water just as well as a $200+ shop-vac.
  11. DonL

    DonL Jack of all trades Master of one

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    Nice.

    Also don't forget the Ground Fault Interrupt.
  12. alternety

    alternety Like an engineer

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    Sorry, not crazy. You have simply suddenly focused on the wrong aspect of this. Electrocution has nothing to do with this. Not related to post.

    The potential problem is this:

    - Sewage systems generate methane (see "energy from manure [pig, cow, sewage systems, etc.] and land fills")
    - methane in the proper air/gas ratio is explosive
    - see lighting farts (a college dorm thing I think)
    - methane is a major component of natural gas
    - sparks ignite methane (see spark ignition of stoves, furnaces, gas grills, propane delivery truck accidents, etc.)
    - putting a mixture of air and methane into a closed container and applying a spark is seriously contraindicated (see air/fuel bombs, houses exploding because of natural gas leak, etc.)
    - people dieing because they entered a septic tank or various sewage/fermentation related spaces because of methane displacing oxygen (could also be carbon dioxide - different reaction)

    + spark from motor

    That is what I am talking about. It would not happen often; based on readily available published events. But it can.
    Last edited: Jan 22, 2012
  13. dlarrivee

    dlarrivee New Member

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    I'll put my tin foil hat on before I use a vacuum around my open sewer line next time...

    Yes, crazy.

    Google LEL (lower explosive limit), you act like popping a toilet off the flange is the same as opening up a live gas line.

    Since you mentioned air/fuel, how much PURE methane do you honestly think is coming out of your NON-PRESSURIZED sewer line?
  14. Hackney plumbing

    Hackney plumbing Homeowner

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    I would be more concerend with breathing the sewer gas than my shop vac igniting the gas while shopvacing a toilets water out. Usually when all the waters gone I turn my vac off and stuff a rag into the bowl. Yank the toilet up and stuff the same rag into the flange. I haven't blown up yet and I do several a week for the past 20 somthing years. Lucky? I think not.
  15. alternety

    alternety Like an engineer

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    As I noted in the initial post, the odds are probably low for causing a problem. I am just not taking that approach. My call.

    I just tried blowing out the water. I used a normal vacuum cleaner because of various irrelevant issues with my shop vacs. Not successful. Probably not enough air volume. Maybe it just does not work.

    The same towel I used to pick up the remaining water in the tank seems to have taken care of the water in the trap. If this was not successful, after I have removed the unit, I will share the experience.
  16. Terry

    Terry Administrator Staff Member

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    Well, you can always use low tech methods. A sponge will work to soak up water.

    Of course, they can carry disease too. That's the scary part about using a sponge.

    But again, for some reason, plumbers don't get sick. So that's not a worry either. Yahoo!
  17. dlarrivee

    dlarrivee New Member

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    Everything can be made difficult for no reason.

    A+ for coming up with a problem that doesn't exist and doing something the hard way to avoid said problem.
  18. alternety

    alternety Like an engineer

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    For some reason I was thinking of methane as heavier than air. It is not, so a vented system would not accumulate it to any real extent. Wrong basic premise.

    Regarding sick plumbers, I actually seem to have a reaction to sewer gases in the air. But I am overly sensitive. I was having problems in the house and finally realized there were two drains that had no water in the trap. Put water in and my reaction to indoor air stopped.

    Thanks for all the responses; sorry about my misguided thinking.
  19. Terry

    Terry Administrator Staff Member

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    Years ago I did some plumbing revisions in the Michigan Street neighborhood; cut the pipes in the basement and wow! It was the worst I had ever seen, I mean smelled.
    Most of the time, the vents through the roof do a good job of venting away whatever is in the waste pipes. So I understand that some homes have more to deal with then others.
    It has always made me wonder about that neighborhood in Seattle though. Like maybe there was something industrial going on.
  20. hj

    hj Moderator & Master Plumber Staff Member

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    quote; Usually when all the waters gone I turn my vac off and stuff a rag into the bowl. Yank the toilet up and stuff the same rag into the flange.

    Then do you remove it and stick it back into the toilet before you reinstall the bowl or its replacement? You may have a compulsive disorder, to worry about any errant odors to that extent. I drain the toilet, remove it, install the new one, then discard the old one.
    Methane, or any other gas, can only "explode" when it has the proper air/fuel mix, and your sewer does not come close to having that mixture. I use a soldering torch by open drains all the time, and in the old days we used oxy/acetylene cutting torches on the drain lines and NEVER blew one up, or even start a fire. The "hazard" is grossly over sensationalized.
    Last edited: Jan 23, 2012
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