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Anyone knowledgeable on septic tanks?

  • 30-09-2021 10:32pm
    Registered Users Posts: 29,386 ✭✭✭✭ NIMAN

    Wondering if anyone knows much about domestic septic tanks?

    Mine, and most of the ones I see around here, have 2 x 4.5in pipes extending above the ground.

    Can anyone tell me what each pipe is for? The last time I got my tank emptied I was told that the 1st pipe served no purpose and could be capped, but I'm not sure if I should do this? It would be the one nearest the house.

    Anyone any idea?


  • Registered Users Posts: 4,706 ✭✭✭ Doctors room ghost

    The pipes above the ground are usually vents on the perculation pipes out near the soak pits.

  • Moderators, Regional North West Moderators Posts: 43,417 Mod ✭✭✭✭ muffler

  • Registered Users Posts: 29,386 ✭✭✭✭ NIMAN

    Thanks for replies.

    Thing is, my 1st pipe, the one nearest the house, doesn't go down into the tank itself like in the diagram. If you put a pole down it, it hits something more or less straight away, like it's a t-junction or something. You can actually see the bottom of it. And recently it has been filling with water and then clearing again. Also, for reference, the lid to my tank is between the 2 vent pipes. Not sure if that's relevant or not.

    When I last had the chamber opened to get empty, I had a guy who knows his drains say he couldn't see what the purpose of the vent was. So he must have seen something that was linked to that pipe that made him think the venting of it wasn't needed.

    Recently it has been vented a bad smell and that's why I'm curious as to whether it could be capped or not.

    I'll not cap it for now.

    Might try to get him back again to explain what his thoughts were.

  • Moderators, Social & Fun Moderators, Society & Culture Moderators Posts: 25,527 Mod ✭✭✭✭ looksee

    Someone who was checking our our treatment system (aka septic tank) said that the first vent was not needed 'because we had an aeration pump' (that he had just put in). I was not sure I understood the logic, but I understood that the central tank had a vent and since there was a through-gap between the two it didn't seem to matter. For different reasons I had a new lid put on the tank, a galvanised one that does not have a vent and there have not been any problems.

    I am not saying that this was a correct approach, but it does seem to be something that is being told to people. I would not be all that confident of the tank guy's abilities, judging by the way aspects of the job were done, but it does seem to be working ok. There does seem to be some expensive cowboy types dealing with septic tanks going on the various people who have given me 'expert' advice and done work for me.

    One thing we did do at an earlier stage was drop a small plastic plant pot into the end of the pipe so it just sat inside it and filled it up with wood chip as a kind of filter, which seemed to help.

  • Moderators, Regional North West Moderators Posts: 43,417 Mod ✭✭✭✭ muffler

    It may well be the inlet chamber and if that was the case it wouldnt really be needed. However the more you ventilate the tank the better.

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  • Registered Users Posts: 4,426 ✭✭✭ maestroamado

    The inlet pipe will be s few centimeters higher than the out which makes sense for function. Both pipe going down goes just under the full waterline in the tank...

    My understand the reason is when matter entering tank it will not be churning around mattter already in tank. The idea being that the undisturbed water will create a kindof protective film on top of this therefore reducing smells... It kinda makes sense i think....

  • Moderators, Social & Fun Moderators, Society & Culture Moderators Posts: 25,527 Mod ✭✭✭✭ looksee

    How can there be undisturbed water when there is an aerator creating bubbles and breaking any surface film?

  • Registered Users Posts: 29,386 ✭✭✭✭ NIMAN

    Unfortunately there is sometimes smell coming from my 1st pipe.

    And when I looked into it the other day, I could see 'matter' lying there!! A few days before there was maybe a couple of inches of water in the pipe, which has since receded. To be fair, there has been torrential rain a lot recently up here.

    Not sure whats going on.

    Post edited by NIMAN on