Stanton Homes - Building Green in the Triangle

Buying a Lot?  Thinking of Building a New Home?

How to Find Out The Cost of Your Septic System

One of the biggest variables in cost for building on your lot can be the cost of the septic system.  How much will your septic system cost in NC?

It depends.  If you're getting a home construction bid, make sure your septic system allowance will be sufficient for the unique requirements of your lot and floor plan. 

Septic System Costs Vary By Lot 

Septic system costs vary widely, depending on soil conditions, size of system, type of system, county requirements, and more.  

A typical septic system in the Raleigh/Triangle area can be anywhere from $3,000 to $15,000, with most conventional or pump systems falling in the middle range. 

What Does "No Perk" Mean?

A special system can run many tens of thousands more - particularly if your lot is rated the dreaded "No Perk", which means the ground is truly not suitable for a septic and many special measures will have to be taken to support one. 

If your lot had a soils test years ago, it may need to be retested.  North Carolina septic and soils requirements have become much more stringent.  Some lots that were approved many years ago may no longer meet the requirements for a standard conventional septic system.  On the bright side, because of these stringent standards you can be confident that your septic system will do its job for many, many years! 

An experienced home builder can look at your septic permit and plot map and give you at least a good idea of what the system is going to cost. 

Here are some of the things the builder will look for to determine septic system cost:

 1.  How large is the septic field? 

The length of pipe required will help determine total cost.

2.   How far from the home is the septic field? 

If more than 100 ft, a backflow preventer will have to be added.

3.  What is the topography of the land? 

A flat, level lot will most likely have lower cost than a lot on a hill.

4.  Is the septic field cleared or densely overgrown? 

The septic field will need to be cleared of brush and of most trees in order for the pipes to be installed.

5.  What depth of soil does your septic permit allow? 

If the nitrification lines cannot be buried deep enough due to soil quality, enough approved soils will have to imported to cover the septic lines.  Add the cost of the soil, plus transportation, and labor for spreading the soil above the septic system field.

6.  Is the system gravity fed or pump fed? 

A pump system will add to the cost.

7.  What type of system has been approved or required?

Has the County approved a standard septic system, or have they required a special system like a panel block system?

8.  Has a basement been requested? 

In this area, most likely an additional pump system will be required, adding at least $3,000 to the building cost. 

Septic systems requirements can vary greatly, even on two adjacent lots.  

But an experienced builder or septic system installer will be able to identify most issues and give a ballpark cost estimate based on seeing the approved septic permit and the plot map of your lot. 

You'll probably want to bring a copy of a floor plan you're considering as well - a basement or a large number of bedrooms can also require changes in the system.    

Writing an Offer 

Remember, you can make an offer contingent on soil suitability.  Talk to your builder about getting a soils test and obtaining information about the type of system required. 

You may also be interested in:

Green Home Building in the Triangle

What is a Green Home?

What Is Geothermal?  Geothermal News and Information

Passive Solar Homes and Ideas

When purchasing a lot, there are two important septic system questions that need to be answered. 

First - does the lot perk?  If the answer is yes, great! 

Second, how many bedrooms is the lot rated for?  You'll want to make sure the rating supports the number of bedrooms you want to build.

But what if you've already purchased a lot that is rated for a 3 bedroom septic system, but want to build a 4 bedroom home?

There are several options that may allow you to build a four bedroom home when your septic system permit only allows a three bedroom home.

First, and probably least expensive, what do you plan to use that fourth bedroom for? 

If that extra bedroom is planned to be an office instead of a bedroom, a few small changes may need to be made in order for your home plan to be approved by the county.

In general, a bedroom has an egress window (a window you could open and escape out of in case of emergency), a closet, and a door, and may also be adjacent or close to a bathroom.   But if your builder converts the bedroom to an office by removing the closet and expanding the doorway to either a wide opening without a door or possibly even a pair of French doors, this could allow you to gain approval to build the floor plan. 

If the fourth bedroom is upstairs, your builder may be able to convert it to an open bonus room or loft.  You'll still have the living space, but it may need to be much more open than originally noted in the plans. 

A second option is the use of a panel block septic system instead of a standard septic system. 

This system can expand the capabilities of a standard system to support at least one extra bedroom. 

But it can also add 25% to 75% to the cost of installing a septic system, depending on how close the original plan came to supporting that fourth bedroom.    It does need to be approved by the county, and a lot of factors can come into play, such as soil type and requirements that vary by county. 

Each case is unique.  In order to make a decision and go over the available options, bring a copy of the septic system permit with the system requirements to a trusted builder or septic subcontractor.   

You may also be interested in:

Green Home Building in the Triangle

What is a Green Home?

What Is Geothermal?  Geothermal News and Information

Passive Solar Homes and Ideas