When to use Grinder vs Sewage Ejector Pump?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by TomWS, May 5, 2011.

  1. TomWS

    TomWS New Member

    Messages:
    12
    Location:
    27312
    I am building a workshop with a half bath about 75-100 feet from my main house. The workshop is on the same side of the house as the septic tank (approximately 50-75ft away from the tank inlet) but the problem is, with the grade of the property, the workshop is not high enough above the level of the septic tank to get proper gravity drainage.

    I think I need to install a pump of some sort. Should it be a Grinder Pump or Sewage Ejector?

    I've looked at both and while it's clear that an ejector would be lower cost, I want to install the correct pump for the job.

    Also, I've read (on a Composting Toilet website) that output from a Grinder pump shouldn't be pumped into a septic tank because the solids are TOO mascerated and will flow out the drain side before settling... Any truth to this?

    If I do install an ejector, where should the well/ejector be located? I don't want an above ground (AKA visible) Sewage Line and think that I'd need to place the well further downgrade (or deeper into the ground) so that the well is gravity fed and has some back pressure on the line to the septic tank.

    Thanks in advance,
    Tom
  2. Redwood

    Redwood Master Plumber

    Messages:
    7,450
    Location:
    Connecticut
    I would go with an ejector pit.
    Where are you located Tom, is freezing an issue?
  3. TomWS

    TomWS New Member

    Messages:
    12
    Location:
    27312
    Pittsboro, NC. Keeping below 12" would be sufficient. I was looking at Liberty's 370/380 simplex enclosures and possibly including the 18" riser so that I have some lift to the Septic Tank inlet. The small 4/10 HP pump looks sufficient for a half bath and 75 ft of run to the Septic system using a 2" line but I'm just not familiar where these types of systems are used/approved...

    Tom
  4. Redwood

    Redwood Master Plumber

    Messages:
    7,450
    Location:
    Connecticut
    They are approved wherever a gravity line cannot be attained.

    You may also want to consider a macerating toilet but I'm not a big fan of them.
  5. Smooky

    Smooky Member

    Messages:
    628
    Location:
    NC
    I'd go with a 2 inch solids handling pump if I was pumping to my existing septic tank.
  6. Smooky

    Smooky Member

    Messages:
    628
    Location:
    NC
    I would still go with the solids handling pump but I think it would be all right to go with a grinder pump. In NC if you are in a new house and the septic system is new, the tank should have a baffle between the first and second compartment and a tee on the outlet. Some counties require a filter on the outlet I'm not sure about Chatham. The tank is designed to allow heavy things to sink to the bottom and grease, oils and other floaters to come to the top. The baffle keeps most these things in the first compartment and the tee is to prevent any floaters that surface in the second compartment from going into the drain-lines. The volume of the tank compared to the daily flow gives some settling time for this to happen. The type system you mentioned is similar to what I see. I like the Zoeller Simplex Sewage Package System or something similar. Myers may also make something similar.... Because it is located inside the building it is considered "plumbing" and would fall under the building inspectors jurisdiction and not the county health inspector.
  7. TomWS

    TomWS New Member

    Messages:
    12
    Location:
    27312
    Thanks! I apologize for not replying sooner - the forum didn't notify me of the update...
  8. ballvalve

    ballvalve General Engineering Contractor

    Messages:
    3,261
    Location:
    northfork, california
    Here is all you might need to know about a great US made pump and its many variations. try i-r-a- w-oods - its blocked here for a link

    http://www.zoellerpumps.com/Home

    you dont need a grinder....
    Last edited: May 22, 2011
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