New and replacement septic systems in Union County, NC
A new septic system in North Carolina starts with the county, not the contractor. The site has to be evaluated and permitted before anything is dug.
How approval works
- A soil and site evaluation by an Authorized On-Site Wastewater Evaluator.
- An application to the county health department for an Improvement Permit and Construction Authorization.
- A licensed installer builds the system to the approved design.
- The county inspects the work before the system is covered and used.
Union County Environmental Health approves every new installation. Permit volume is high in this fast-growing county, so allow time, especially for new construction or a home sale with a deadline.
What a new system costs
| Work | Typical NC range | What moves the price |
|---|---|---|
| New septic system | $4,500 to $14,000 | Soil, system type, lot access, permit and evaluation fees |
| Conventional gravity system on good soil | $3,000 to $7,500 | Lower end, when soil and depth allow a simple design |
Ranges are statewide estimates from third-party cost guides, not quotes. Prices in Union County vary with tank size, access, soil and permit requirements. Get written quotes before work starts.
Cost guides disagree because soil and site decide the price. A lot that needs an engineered system costs far more than a conventional one.
Questions to ask an installer
- What is your septic installer license number?
- Who handles the soil evaluation and the permit application?
- What system type does my site need, and why?
- What happens to the price if the soil evaluation calls for a different system?
- What does the warranty cover, and for how long?
Common questions
How long does a septic system last?
A well-maintained system typically lasts 20 to 40 years. Soil conditions, the water table and how the system is used can shorten that.
Do I need a permit to replace a failed system?
Yes. Replacement needs an Improvement Permit and Construction Authorization from the county health department before installation can begin.
Last reviewed November 2026. Prices are estimates, not quotes.