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Thread: Options for large sewage basin

  1. #1

    Default Options for large sewage basin

    Hi Everyone,

    I'm building a new house that will require a sewage pump and the local sewer district standards call for a vault capacity of 300 gal above the high wet well alarm level. Needless to say, that's a big tank, around 500 gal total I'm told. I've done a web search and the biggest poly tanks I can find are around 100 gal with fiberglass tanks going up to about 250 gal. Is a concrete vault my only option here? Or can two or more smaller tanks be plumbed together into a single system?

    Weight is an issue here, unfortunately. An easement disagreement late in the project forced me to abandon my planned gravity line and the location for the sewage basin isn't easily accessible by a machine that could lift a concrete vault.

    Any advice would be appreciated.


  2. #2
    Architect Spaceman Spiff's Avatar
    Join Date
    Aug 2004
    Salt Lake City, Utah


    Because of all the problems I have heard of with plastic and fiber tanks underground, I would try as hard as possible to get a concrete tank. The concrete and a crane to lift over your house could be less than a fiberglass tank.


    Take a look at your local farming supplier, they usually have large tanks that are used for animal waste and might be allowed for sewage systems.
    You could also have a fiberglass tank manufacturer custom build one for you. There are companies across the US that do custom tanks all day long and ship them to the customer via truck for all sorts of purposes.
    Spaceman Spiff aka Mike

  3. #3
    DIY Member pump's Avatar
    Join Date
    Oct 2005


    A 48" Diameter by 60" deep fiberglass basin is going to be 469 gallons of capacity. A 48" X 72" is 563 gallon capacity. It will run you $2000 or more for the 48 x 72 depending on your area.

    48" diameter for every inch in height is 7.83 gallons
    60" diameter for every inch in height is 12.24 gallons
    36" diameter for every inch in height is 4.41 gallons

    Hope this helps!

  4. #4


    Thanks everyone. Looks like the cost of a concrete vault and a crane to lift it would definitely be less than the cost of a fiberglass vault.



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