Septic Tank on a multifamily property? Yes or No go?

Septic Tank on a multifamily property? Yes or No go?

San Francisco Bay Area · Member since 2018 · 33 posts · 31 votes

What are your opinions on having a septic tank for a multi-family property? I'm evaluating a deal and the sewer doesn't go to the city, it's a septic tank property. Owner said they just replaced it with a brand new septic tank. Does it last long? Do you stay away from it due to maintenance? Or is it ok? 

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Morris County, NJ · Member since 2020 · 5k+ posts · 2k+ votes
3y

@David Liu

Did they also install the leach field?  Or just the tank?  The tank and the system can last 30, 40+ years.  While they are expensive to install, its a one time cost.  You just need to pump out the tank every few years normally.  Overall, it CAN be much cheaper than sewer...

The issue lies in what your tenants may send down the drain.  The big no-no is oils, e.g. cooking oils and grease.  In a septic system, the "water" drains from the tank into the leach field, i.e. usually some grassy section of your lawn.  If the oil gets out there, it plugs up the soil and it can no longer drain.  Then, the solution is digging it up and getting a new leach field.. $$$

I normally would stay away from septic, but thats tough since most of the property around me is septic.  If its common for your area, then people will know how use it.  Its the "city-folk" get "shocked" --- although, you aren't supposed to pour grease down a sewer either since it can/will harden and plug up the sewer lines.

How many units are you talking about for your multi-family?

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  • Bjorn AhlbladPro Member
    Investor · Shelton, WA · Member since 2017 · 6k+ posts · 6k+ votes
    3y

    Septic tanks last a very long time if they are properly sized. The ones I have had were for a single family home, and another on which is 2 houses on the same septic system. Yes they are expensive to install but your water/sewer bill is expensive too. 

    My current septic system was installed in 1992 and it is still going strong. What do you mean by 'multi family' and is there a well too?

  • Morris County, NJ · Member since 2020 · 5k+ posts · 2k+ votes
    3y

    @David Liu

    Did they also install the leach field?  Or just the tank?  The tank and the system can last 30, 40+ years.  While they are expensive to install, its a one time cost.  You just need to pump out the tank every few years normally.  Overall, it CAN be much cheaper than sewer...

    The issue lies in what your tenants may send down the drain.  The big no-no is oils, e.g. cooking oils and grease.  In a septic system, the "water" drains from the tank into the leach field, i.e. usually some grassy section of your lawn.  If the oil gets out there, it plugs up the soil and it can no longer drain.  Then, the solution is digging it up and getting a new leach field.. $$$

    I normally would stay away from septic, but thats tough since most of the property around me is septic.  If its common for your area, then people will know how use it.  Its the "city-folk" get "shocked" --- although, you aren't supposed to pour grease down a sewer either since it can/will harden and plug up the sewer lines.

    How many units are you talking about for your multi-family?

  • San Francisco Bay Area · Member since 2018 · 33 posts · 31 votes
    3y
    Quote from @Bjorn Ahlblad:

    Septic tanks last a very long time if they are properly sized. The ones I have had were for a single family home, and another on which is 2 houses on the same septic system. Yes they are expensive to install but your water/sewer bill is expensive too. 

    My current septic system was installed in 1992 and it is still going strong. What do you mean by 'multi family' and is there a well too?

    It's an 8 unit. Not sure if they also installed a leach field. That's good to know. Thank you Bjron and David for answering. 
  • Alecia LovelessPro Member
    Member since 2019 · 3k+ posts · 2k+ votes
    3y

    I have two properties with septic systems, one has two houses with three units and the second is an 8 unit apartment with 2 septic systems. On ALL of the properties I put under contract with septic systems I get a separate septic inspection from an independent septic inspector. The inspection runs about $600, I paid $1200 on the 8 unit with the two systems, and the inspector will tell you how the tank looks, how the plumbing looks coming from the building, should tell you how the lines are under ground, and then dig up small sections of the leech field to tell you the current condition of the field and how much life it has left in it so you will know approximately how long it will be before you might need to think about replacing the system. My inspector does not want the tank pumped before the inspection he wants it in it’s current condition. 

    I’ve had inspections done 4 times, and ended up not buying 2 of the buildings. Each time the inspection played a vital part in the due diligence process. I highly suggest getting one even if it means getting a contract extension. I would recommend the independent inspector as opposed to the septic company doing it because they will be trying to sell you a new system and not be impartial. 

  • Morris County, NJ · Member since 2020 · 5k+ posts · 2k+ votes
    3y

    @David Liu

    Not sure about your market, but septic inspections here normally will snake the tank and leach field with a fiber optic line / camera.  So, you'll have photo evidence of the inside of the tank (never pretty) and of the leach field.

    Definitely find an inspection company that only does inspections.  Companies that do inspection and remediation just have a perceived conflict of interest, while I am not saying that they are all crooked.

    Look up your municipal / state (for me its State) laws on septic systems.  If it exists, it will give you a better understanding of your septic system requirements, and potentially even inspection standards.

    As for a an 8 unit, i've never done residential multi-families much less commercial multi's..  I know in my area similar ones exist with septics.  Many restaurants have septics as well.  The tank and leach field just need to be sized properly.  As far as "bad actors" dumping stuff down the drain that isn't supposed to.. the best I've figured out one could do is pump the tank more frequently.  The thought is you want to pump it out before the oils make it out to the leach field.  The guy doing the pumping is supposed to drop a stick down or something to see how much crud is at the bottom and floating on the top.  That gives you an idea of how frequently the homeowner should be pumping...

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