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Thread: Septic system questions...

  1. #1

    Default Septic system questions...

    Hello, I'm new to this forum and have a few septic system questions. The septic tank at my parents house has been working just fine until a few years ago. First of all it hasn't been pumped in probably over 20 years (I know...). The tank appears to be a single tank with a divider and an overflow tube from one side to the other. Several years ago they replaced a length of lateral line and it seemed to be working until just recently. In January of this year we had it pumped and the guy said the second side was full of sludge so he pumped that also. We started having some more problems and had another guy come out and pump it again and install a new lateral line. I looked in the tank recently and saw that the second side was full of sludge. I took the first guys word that he fully pumped it out but didn't verify how much he left in it and I also don't know to what extent the second guy pumped. My questions is will this sludge compromise the new lateral line? Do we need to have it pumped again to get ride of all of the sludge. Any suggestions?


  2. #2
    Join Date
    Dec 2003
    Kent, WA


    It is normal for there to be sunken sludge and floating scum in a septic system. In a 2 stage tank (either 2 tanks, or one with a divider), the second tank should have much less scum and sludge than the first side. The output pipe should have a baffle at the top to keep floating scum from exiting the tank. The bottom of the output tee should take water from the middle of the tank so the sunken sludge doesn't obscure it.

    The purpose of pumping is to remove that sunken and floating stuff when the layers have become too thick. When too think the tank volume is reduced and you risk the items exiting the tank which will clog your field.

    Examining the tank should be done on a 3 year cycle. You need to measure the floating scum and sunken sludge thickness. If you don't want to do this, just call a pumper and have it all pumped out, but ask how thick those layers were and if the tank really needed pumped. If it could have gone longer, repeat in 4 years. I don't think I'd ever go more than 5 years without pumping unless you are one person living in a house designed for 10.

    If your laterals are clogged or slow, the tank will overflow with water and you may see wet spots in the yard at the tank (or worse, you'll get a backup in the house usually in the lowest bathtub or shower). Overflows can also allow the floating scum to get into the second half of the tank or out into the field (which will clog it). Usually, when a pumper pumps the tank, he'll look to see if water is flowing into the tank from the field. That would be a sign that the field is saturated and not keeping up. If you don't have a gravity tank (i.e. there is a pump in it that pumps water up to a field), then you can't look for this backflow and need other ways to assess field vitality. Fields usually last about 40 to 50 years. When they fail, you need to put in a new one. Replacing a line or two is just borrowing time. The rules will be more stringent now than they were 40 years ago, and that can cause issues and increased cost when replacing the field.
    Kent, WA

  3. #3


    Thanks for the information. I plan on having another company come out in about a year or so to asses the tanks. So far so good.

  4. #4

    Default SEp

    Unfortunately, between the age of the septic tank and the problems you are describing, you might want to consider to have it replaced. It is very expensive option, but with the neglect of tank and the problems you are describing you might have to do it.

    Please check out <link removed> for more information on how often a septic tank last and how often it needs pumped out to keep it up and running.
    Last edited by suemarkp; April 26th, 2017 at 11:30 AM.

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