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Discussion Forum

Sewer Back Flow Preventer

Paul_Z | Posted in General Discussion on June 7, 2009 10:57am

A customer of mine had a sewer back up last week.  The water came up through the basement shower drain and flooded the basement.  The flood happened during a rain storm where we got 5 inches of rain over night.

The house is in Washington DC and the sewer system is very old and is in desperate need of replacement to keep up with the present volume of sewage.  The sewer system also processes a lot of unwanted storm water.  Most of the houses in this area are very old and they have exterior drains that connect to the sewer system.

The sewer utility company (WASA) says that they will not take any responsibility for the resulting flood damage or flood clean up.  Wasa’s response was “it has been written into law that they are not responsible for any property damage to residences due to flooding from their sewer system if they (WASA) did not know of the problem prior to problem occurring.”  Sounds like a blanket no fault law for WASA if this is indeed true.  My local sewer utility (WSSC) does pay for sewer back up problems that are the result of a failure of their sewer system.  Anyone know if there is any action that can be taken against WASA?

My customer would like to know if there are any preventive measures they can take to ensure that this problem will not occur again.

I have heard of sewer back flow preventers that are mounted inline on the sewer main as it exits the house.  I believe that the main sewer line exits the house under a newly remodeled bathroom.  I will confirm this with a pipe locator.  If I am correct this type of sewer back flow preventer would require tearing up a lot of the new bathroom.  There would also be a back flow preventer access cap somewhere in the middle of the bathroom floor.

Are there sewer back flow preventers that can be installed in the front yard and still be accessible for service?  I am sure that the main sewer line in the front yard is at least 8 feet deep.

I am looking for options and available products to remedy this problem.

Thanks

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Replies

  1. User avater
    shelternerd | Jun 07, 2009 11:04pm | #1

    they do make flap check valves for ejector pumps that would proably work for this. I use them in PVC and you would just insert it in the line where the sewage leaves the basement. You could also put in a stop valve to get a more positive shut-off than a flapper. Of course once you shut it down you have to be sure to stop flushing anything inside the house.

    ------------------

    "You cannot work hard enough to make up for a sloppy estimate."

  2. plumbbill | Jun 08, 2009 12:01am | #2

    What they need is a "backwater valve" & if the downstream manhole cover is above their lowest fixture a backwater valve is required under the UPC code.

    Here is a link to one the big names in the business.

    http://www.jrsmith.com/products/backw/7012_7022.htm

     

  3. jimk | Jun 08, 2009 01:24am | #3

    First off, not a plumber... was talking to a guy who works for a drain cleaning service who had at one time lived in a basement apt. that had a gate valve installed in the main as it left the apt. He said he would never live in a basement apt. again without one (considering what he sees on a daily basis)

     

    As I see it, the obvious drawbacks are you have to be at home and aware of the problem to be able to close the valve,and secondly, as someone else said,you can't use any water until the problem outside is taken care of.(but it beats a house full of poo)

     

     

  4. MDFContracting | Jun 08, 2009 07:51am | #4

    Plumbing code in my town states that a backwater valve on a main line must be a "Full Port" backwater valve meaning that the door must be open to sewer gas moving in the direction of the main stack so it can vent out of the roof. This is accomplished with a floating door that will rise up and shut in the event of a backup. Check Plumbing suppliers, this is not something you will find at HD.

  5. MikeHennessy | Jun 08, 2009 03:46pm | #5

    How about one of these in the shower floor drain:

    http://tinyurl.com/m6gfdk

    (I'd post a pic, but my pie runneth over.)

    Mike Hennessy
    Pittsburgh, PA
    Everything fits, until you put glue on it.

    1. rez | Jun 08, 2009 03:58pm | #6

      Mike, you can click on click here to find your old attachments found at the bottom of the attachment page when trying to attach pics. 

      When your attachment listing opens click on Click here if you think that we have counted your attachment space incorrectly found at the bottom of the page.

      That will reset your 1000KB limit even if the pie chart doesn't register it. You can do this over and over if needed. 

      Edited 6/8/2009 9:02 am ET by rez

      1. MikeHennessy | Jun 08, 2009 04:17pm | #7

        Yeah, but I'm in a civil disobedience mode.

        I figure if we don't let the number-crunchers at Prospero have their way without a fight, they'll reconsider their posting limits. Keep the pressure on Taunton so they'll keep the pressure on Prospero.

        If we just exploit workarounds, the Prospero "improvements" will likely stick. Don't want that!Mike HennessyPittsburgh, PAEverything fits, until you put glue on it.

        1. rez | Jun 09, 2009 07:06am | #11

          heh ya, but you know as well as I that nothing's going to change

          and after a time of squawking we'll all just deal with it and move on as always.

          We're just posters on their website that helps them sell magazines

          managed by a small assigned taskforce of mods as labor for hire working to keep a ship afloat by necessity. 

          1. MikeHennessy | Jun 09, 2009 03:10pm | #12

            Yeah, but in this case, I think Taunton's just as pixed as we are. They're a paying customer who can take their money and run. If we roll over, there's no incentive for 'em to grouse to the Mzingavites.Mike HennessyPittsburgh, PAEverything fits, until you put glue on it.

          2. rez | Jun 09, 2009 06:02pm | #13

            Point. 

  6. rdesigns | Jun 08, 2009 06:44pm | #8

    The best option, if they're up for the cost, is to install a backwater valve on the drain line(s) that serves the basement fixtures only, since these are the only ones lower than the next upstream manhole, and thus not subject to flooding from a backed-up sewer main.

    A backwater valve is just on one-way check valve  that is installed in a horizontal drain line. The working part is a hinged flapper that requires only light pressure to open in the direction of flow. A backflow from the sewer system closes the flapper against a seat. Access to the flapper is provided by by an o-ring gasketed screw-in top, access to which is down thru a tube that covers the access lid; the top of the tube can be cut off flush with the floor. A thin lid covers the top on the access tube.

    If you just install a backflow device on the shower, there is the risk that the level of the backed-up sewer will rise enough to spill out the next lowest basement fixture. (Toilet or whatever.)

    If you are allowed to install a BWV on the whole house drain, this should prevent main sewer backups from entering the house, but there is a small risk that the flapper could get hung up and begin flooding the basement without anybody knowing it if the upstairs fixtures continue to get used without anybody going down in the basement to see the flooding--at least the sewage would be their own, and not the neighbors'.

    Sioux Chief Manufacturing makes ABS and PVC BWV's that are much cheaper than cast iron ones, and they are more trouble-free, since they work with a very light action on the plastic flapper. They don't corrode, either. They make them in 2, 3, and 4 inch sizes, and the access tube/cover are included.

  7. ravz | Jun 08, 2009 07:37pm | #9

    http://www.backwatervalve.com/

  8. pixburd | Jun 08, 2009 08:39pm | #10

    Paul,

    The same thing happened to me during 8/07 storm. First advice -- you have 24 hrs to clean up or mold with start. I doubt your insurance will help either. I canceled State Farm after my flood -- they didn't even answer my call. Your sewer authority may have liability on the 2nd backup -- my neighbor presently is in litigation over this, they won arbitration with 3 judges, but the authority is appealing which means it goes to a jury trial -- how stupid -- instead of paying $10-20k in damages to the neighbor, they will shell out $100k in legal fees. I think they will fight this one to the death.

    My sewer authority did install a backflow preventer outside my house just after the vent and the trap. It has a tube within a tube connected to a flapper which I can pull out for cleaning. Yuck! But w/o cleaning, the flapper may not close. During the last storm I had fountains of water coming up the bsmt drains.

    Another option is to place float valves in the bsmt drains like the other poster MikeHennessy from Pixburd said. I tried to do this also, but I only found float valves sized for plastic pipe, and would not work on my cast iron drains.

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