Toilet traps drying out. How to prevent?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by carnutal, Jul 21, 2006.

  1. carnutal

    carnutal New Member

    Hi All,

    I have a home that sat unoccupied for 5 months and when I came back all my toilets had dry traps. I filled up all the traps in the sinks, laundry etc. but is there some trick or product to prevent this from happening over an extended period of time? I'm concerned about sewer gases. Thanks for any help. Alan
  2. Bob NH

    Bob NH In the Trades

    New Hampshire
    Put some propylene glycol (RV Antifreeze) in the traps. It is safe.

    Other things (ethylene glycol, motor oil) will work but may not be good for the system.
  3. Gary Swart

    Gary Swart In the Trades

    Yakima WA
    Water evaporates, so it's a natural occurence for traps to dry out over time. RV antifreeze is about the only thing you can put in that will last a long time. Do not put regular car anti freeze or petroleum product is a drain ever. If possible, you could occasionallly "recharge" the traps with water, but if you are in a cold climate and the house is unoccupied and unheated in the winter, then the RV anti freeze is best, but then you should also drain the pipes and toilet tanks for the entire house.
  4. Large sponge with a string tied to the sponge and the toilet seat. Lift the seat and the sponge comes out. No worries of anything to provide a seal.

    A handyman told me of that trick........I still tell people to use something out of their kitchen like vegetable or corn oil. Something that isn't harmful to the piping.
  5. prashster

    prashster New Member

    Vegetable oil = bad. It can promote bacteria growth. Although, since it sits on top of water, it acts like an effective lid in disabling evaporation. So, you only need a very little bit on the drain side to be effective. I've heard it can also coat pipes and hurt drainage (although my wife pours a decent amount down OUR trap at home to no as yet adverse consequence).

    PG or antifreeze is good bkz it's harmless to ground water, doesn't promote bacteria. It dissolves with water. If you just pour a little bit in there, the water may evaporate around it and you'll be left with a low-level - but not-empty trap. You have to pour enough pg in there to cover the whole bottom of the trap U.

    - p
  6. carnutal

    carnutal New Member

    Thanks guys for all the great ideas. The sponge idea sounds great as well as the other suggestions. This is a fantastic valuable site.
  7. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    New England
    I would think the sponge would act as a wick and dry it out faster...
  8. The water in the drain is in a trap or it would be running through and down the pipe.
  9. SteveW

    SteveW DIY Senior Member

    Omaha, NE
    Just to add a cautionary note -- ethylene glycol is HIGHLY toxic to house pets (propylene glycol is less so, but not completely safe) so take care if you have a dog who might be tempted to take a drink from the toilet.

  10. The way this handyman put water in the trap whatsoever. Just one of those large sponges stuck in the trapway with it dry.

    The string is to make sure that no one forgets that the sponge is in there if for some reason it gets pushed back too far.

    The sponge works like a cap of sorts.....keeps sewer gas and flies from entering the house.

    He said he does winterizations and too often people would come behind him......flush the toilet,turn it back off and take away any protection that was offered. Just urinating in the toilet a few times can cause a loss of protection as well.
  11. bobball

    bobball New Member

    Toilet traps drying out. How to prevent?

    I'm about to leave a condo in Tucson Arizona for the next 9-10 months. In past years, I've kept the plumbing going, asking neighbors to run water in sinks, tub, shower stall and toilets to keep traps filled, sewer gases and cockroaches out.
    That's worked for me. But the condo units are nearing 40 years old, and in other units there have been leaks in plumbing, some not caught for a few days, with serious damage.
    So I want the water shut off.
    Two choices:
    RV antifreeze, and from what I read here and elsewhere, the evaporation rate may be low enough to keep the traps filled with only occasional topping off.
    Or blocking the drains. My first thought is wadded plastic bags, the kind I take groceries home in. It seems like no problem for the small traps, and not much of a problem for the two toilets. I'd already thought of a string to keep the bags from disappearing and clogging the drains.
    I haven't found information on "summerizing" a winter home, only the opposite. Will these ideas work? Which is better?
    Last edited: Apr 27, 2009
  12. hj

    hj Moderator & Master Plumber Staff Member

    Cave Creek, Arizona

    The sponge does absolutely nothing for all the other traps in the house which will dry out faster than the toilet because they have less water in them.
  13. SewerRatz

    SewerRatz Illinois Licensed Plumber

    Chicago, IL
    This is from the Illinois Plumbing Code book. They say Vegetable oil can be used.

    Section 890.410 Fixture Traps/Continuous Waste

    f) Trap Seal. Each trap shall have a water seal of 2 inches except where a deeper seal is required to prevent the loss of the trap seal by evaporation. Where loss of the trap seal may occur due to evaporation, one of the following shall be used:

    1. Vegetable oil may be added to the trap.
    2. A deeper seal not to exceed 8 inches may be used.
    3. An automatic trap primer may be used.
  14. hj

    hj Moderator & Master Plumber Staff Member

    Cave Creek, Arizona

    1. Vegetable oil has to fill the trap, because the water underneath it will evaporate on the outlet side just as it will on the inlet.
    2. A deep seal trap just takes longer to evaporate, but it will if no water is used.
    3. A trap primer only works when water is used somewhere, depending on which type it is, so it would also be ineffective in a vacant house.
  15. iminaquagmire

    iminaquagmire DIY Senior Member

    I work for a company that does winterizing for insurance companies on foreclosed homes. Their requirements are to pressure drain the supplies, shut off all stops, fill all of the traps with RV antifreeze, then mark the points of use with warning stickers across the fixtures and at the front door.

    Houses that were done over a year ago still have full traps.
  16. Andrew P.

    Andrew P. Electrical Engineer

    Near San Jose, California
    Vegetable oil = bad

    The problem with vegetable oils is that they oxidize and become rancid. Rancid oils adhere to surfaces like glue and are very hard to remove, both from the toilet trap and the drain pipes.:mad: Moreover, oil and grease on the drain pipe walls can act like a magnet for toilet paper and other solids, which can quickly "snowball" into a complete clog of the drain line. (I got this bit of wisdom from talking to one of our public works crews as they were blasting out a clogged sewer main on my street with a high-pressure hose reeled out from a vacuum sewer cleaner-jetter truck. I asked if the grease came from people pouring it down their kitchen sinks, but the foreman didn't think so. He said it was more likely an accumulation of soap scum and body oils from baths and showers.)
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