Sewer, septic, or a package plant

Public sewer

The lots connect to a public sewer system. The land needs a line within reach, capacity in the line and at the treatment plant, and the utility’s agreement to serve. The developer usually pays to extend lines, and to build pump stations where gravity flow does not work.

Sewer lets lots be as small as zoning allows. Soil does not limit the lot count. Utility policy does. Some towns serve land outside their limits only after annexation, and some limit the flow they commit to new projects. The written answer is a will-serve letter or an allocation.

Individual septic systems

Each lot treats its own wastewater in the ground. That works only where the soil can take it. A licensed soil scientist evaluates the soils, and county environmental health issues the permit for each system. Depth to a seasonal high water table, soil texture, rock, and slope decide whether a lot passes and which kind of system it needs.

Septic changes the math. Each lot needs room for the system and often a repair area. Lots end up larger than zoning alone requires, and some lots that fit on the plan fail in the field. The soil map gives a first warning. A failed soil evaluation removes a lot.

Private package treatment plant

A package plant is a small treatment facility built for one development. It serves land that sewer does not reach and that soils cannot serve with septic. State regulators permit the plant and its discharge or land application. When a private company operates it for paying customers, the North Carolina Utilities Commission can have a role in rates and service.

A package plant lets lots be smaller than septic allows. It adds permits, construction cost, and an operator for the life of the plant. Some local governments discourage or restrict them. A land application system needs land of its own.

How each path changes yield

• Sewer. Zoning, streets, stormwater, and open space set the lot count.
• Septic. Soil sets the lot count, often below what zoning permits.
• Package plant. Zoning sets the lot count, less the land the plant and its disposal area take.

This is why two tracts with the same zoning can hold very different numbers of homes. The lots-per-acre calculator shows the arithmetic once you know the lot size.

What the public record shows

Utility maps show sewer lines near a tract, where the utility publishes them. The USDA soil survey shows soil types and their septic limitations at survey level. State permit records show existing treatment plants and discharges nearby. Planning documents show where a town plans to extend sewer.

The record cannot show capacity, whether a utility will serve, or whether a given lot passes a soil evaluation. The utility, a licensed soil scientist, county environmental health, and state regulators confirm those. See what we check on water and sewer and on flood, wetlands, and soils.

Questions

Can a subdivision use septic instead of sewer?

Often, where zoning allows lots large enough and the soils pass. Some ordinances require a sewer connection when a line is close. Planning staff and county environmental health confirm which rule applies.

Does a soil map tell me if a lot will pass for septic?

No. The soil survey is drawn at a broad scale. A licensed soil scientist evaluates the lot, and county environmental health decides.

Who owns a package treatment plant after the homes sell?

It depends on the arrangement. A private utility, a homeowners association, or a local government can own it. Ask a land-use attorney and the state regulator before you plan on one.