We recently had our septic system inspected and were informed that the tanks themselves were shot and would need to be replaced. I'm in the process of getting estimates but in the meantime, I was wondering if someone could describe the procedure and ballpark costs. I assume we're talking about several thousands of dollars.

Additional Information:

  • House is located in Aptos, CA
  • House is located on a mostly flat lot (9000 sq ft) and is elevated up from street. Front-yard is small and that's where the current septic tank is located.
  • House is 48 years old
  • Existing septic tank is concrete and 2250 gallons (according to inspections).
  • Still waiting to complete details in report.
  • 1
    Seems like this could vary greatly based on locale, size of tank, depth of tank, condition of tank, and many other variables. Adding more details might get you a better estimate.
    – Tester101
    Sep 23 '10 at 19:55
  • @Tester101 Great suggestion. I added additional details.
    – Mike B
    Sep 23 '10 at 20:23
  • You might want to have the tank checked for a missing plug at the bottom center of the tank. As a real estate broker in Rhode Island, I have had several homes where the tank level dropped only to have this plug cemented. The thought is that it was sucked out with the sewage when it was pumped. It's only a $200.00 fix if it works.
    – user23188
    Jun 19 '14 at 12:55

I found some rough estimates at costhelper.com

Installing/replacing a conventional septic system (including the tank) averages $2,000 -$5,000 in the Midwest, but can be $4,000 -$12,000 or more in areas where materials and labor rates are higher.

Enhanced, engineered or alternative septic systems that use mounds, sand/peat filters, aerobic systems and/or constructed wetlands can cost $10,000 -$20,000 or more, according to the Rhode Island Regional Water Quality Program. These alternative septic systems work better than the conventional approach for sites with high groundwater or slowly/rapidly percolating soil, or near drinking water supplies, wetlands, coastal ponds or other water resources.

The cost of a septic tank alone runs about $500 -$1,800 depending on size (ranging from 300-1,000 gallons) and type. Piping and other needed items adds another $100 -$200 to the total cost of materials.


This really depends on location. Locally estimates are in the 50K-100K range to go from design to installation.

  • Thanks Duane. Thankfully the leech field tested fine in the flow test -- it's just the tank that needs to get replaced. We're getting estimates.
    – Mike B
    Sep 27 '10 at 22:29

In northern New Mexico, I just had a whole new tank + field put in for $4,200. The tank is a 1,000 gallon model with an effluent filter and a vented lid. The field is standard perforated PVC pipe in gravel-filled trenches. Included in the price was filling in the old tank.

2,250 gallons sounds like way overkill unless your house has like 10 people living in it! You can probably get away with a tank half that big, if not smaller.

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