Septic tank + drain field

Standard on-site treatment; anaerobic digestion in the tank, dispersal through the field. The classic design is entirely gravity-fed, no pump, no power, which is what makes it resilient to an outage. That holds only where the site allows the drain field to sit below the tank outlet: on flat ground, a high water table, or where the field must go uphill, a lift-station pump is required, and the system stops being passive. Check the fall available on your site before assuming the passive version applies.

Cost
Medium
Upkeep
Seasonal
Skill to build
Intermediate
Lifespan
30-50 years for a concrete or fibreglass tank; drain field per the permitted soil/drainage-field figure. Where site levels force a lift-station pump, that pump follows the usual 10-15 year residential pump cycle and becomes the shortest-lived part of the system.
Embodied carbon
Medium
Space / material use
High
Output timing
Continuous process
Skill to repair
Intermediate
Regulation (FR example)
On-site sanitation (assainissement non collectif): the installation must be declared to and approved by the local SPANC before work starts, and is subject to periodic inspection. Arrete du 7 septembre 2009 modifie.

Note: Cost, carbon and footprint are rated against the other options for this same need, not in absolute terms.

What your site needs

Soil percolation rate and area sufficient for a code-compliant drain field; enough fall between tank outlet and field to run on gravity, otherwise a powered lift station is needed

Inputs

Outputs

Sources

What this page does not tell you

No sizing or quantities: how much a technique yields, and how much a household needs, both depend on the build and the people, so the catalogue compares options rather than dimensioning them. It carries no bill of materials and no build sequence, and it is written for an oceanic, clay-soil climate (Normandy, France). Regulatory notes are indicative and need confirming locally.