Residential Septic System Cost

[msquared48]

I have a friend whose septic system failed and has to be replaced entirely - apparently is forced to replace it by the county, for whatever reason. It is going to be placed on a different area of the lot.

Question: For a 2500 square foot three bedroom house, for the engineering design, materials and installation of the septic system (not a sand filter), does $22,000 US seem reasonable?

Mike McCann
MMC Engineering

 

[Drumchaser]

wow...I paid 4K for an aerobic system a few years ago...comparable SFage.

sounds extremely extreme, unless there is more to the story.

 

[bimr]

Unless you have extreme site requirements, the cost should be less than $10,000.

 

[PEDARRIN2]

It will depend on the requirements of the AHJ.

The house I used to live in (SW Ohio) had a failed septic system - the leachfield had become overgrown by brush and trees - also the septic tank was too small. It was an old farmhouse with a homemade (~700 gallon) tank. We were a family of five.

The County health department was requiring a new tank and modified mound system be put in. They would not allow us to use a leachfield again - didn't have enough property. For a leachfield, they wanted a back up area which would have required about 0.75 acres. We had slightly less than a single acre.

The lowest estimate was ~$20,000.

That was about 5 years ago.

 

[civilman72]

I agree that a modified mound systems can run in excess of $20k. However, the design and installation of a "simple" septic sytem can also run as low as $5k. A lot of it relates to your soil type/perc rate, which directly affects the size of your leech field and costs.

Plus, there are always site-specific contraints to consider. At my own house, we added some bedrooms on, which necessitated an upgraded septic system, and the existing leech field was old, so we decided to go with a whole new system. However, in order for the leech field to work in the one area that made sense on the lot, we had to pay for rock blasting, which increased our costs by $8k-$9k. Cool thing was, because we blasted hard granite almost 20' below the leech field, I basically have 20' of sand/gravel below the leech field, so the leech field should last a LONG time. Too bad this doesn't correlate to increased building value...

 

[ptmoss]

A three bedroom house in the northeast, except Maine - new system including design/permitting costs - $22,000 would not be wholly unusual when dealing with the typical hardpan soil. Especially if a pump is required. Somewhere on the higher side of average, but not unusual.

For soils with fast water movement the cost might be as low as $10,000.

Maine does things different than the other states, and I think better, and the cost in that state might be more in line with $5000-10,000. In Maine though, the criteria to become a Site Evaluator, necessary to design systems, is pretty tough and you really need to know your soils. Because of that they're a bit more liberal on sizing systems, but apparently with a failure rate that's as good or better than the neighboring states.

Pete

 

[tjkall]

Mike:
I see that you are in Colorado. My system has been approved by CDPHE as an advanced treatment system and, I can say that after having worked on a number of large projects in Colorado for the last decade, you have some of the highest septic system costs I have seen anywhere. What I have found is that contractors will generally triple the parts price for a total price. I requested bids for a subdivision I was designing and one contractor quoted $51/ft to install 4" dia. building sewer 4' in the ground. The soil was like flour, no rock. I called him and told him I thought he had his numbers transposed (51 instead of 15)....Nope...51 bucks a foot he said.

I have a system going in where a competing system had been specified but the cost exceeded the cost of the owners manufactured home. The engineer told me that the cost of my system was not much more than a conventional septic tank and drainfield.

Tom

 

[msquared48]

I live in Washington, but am licensed in Colorado too.

Mike McCann
MMC Engineering

 

[mricks]

We paid about $14k for ours last year in Georgia. We have a 42" mound (60x100 flat surface with 4:1 slopes) in addition to a septic tank and pump.

FWIW