Septic Design, Sizing & Site Evaluation
Before a permit gets filed and before excavation starts, your site has to be evaluated and your soil has to be tested. This is the step that determines everything else.
A site evaluation and design is the technical foundation of every septic project — new installation or replacement. It answers three questions that determine your entire system: how much wastewater your home will generate, how well your soil can absorb it, and where on your property a system can legally and practically go.
What a site evaluation covers
- Property boundaries, easements, and access for construction equipment
- Distances to existing or planned wells, both on your property and neighboring ones
- Setbacks from structures, property lines, and any surface water
- Slope and drainage patterns across the proposed system location
- Soil type and depth to bedrock or restrictive layers like caliche
The percolation test
A percolation (perc) test measures how quickly water moves through your soil — typically by digging a test hole, saturating it, and timing the drop rate. In much of the Albuquerque metro, that number can vary sharply within a short distance because of caliche layers and mixed soil types, which is why a test performed on your specific lot matters more than a neighbor's results or a general area assumption. Read the full percolation test & soil guide for what the process actually looks like.
From soil data to a permit-ready design
Once the site evaluation and perc test are complete, your design documents the exact tank size, drainfield type and dimensions, and system layout — the package that gets submitted with your permit application. A design based on real site data is what gets approved on the first pass; a generic or estimated design is the most common reason permit applications get sent back for revisions.
Schedule your site evaluation
This is the first real step for both new installations and replacements. Tell us about your property and we'll connect you with a qualified evaluator.
- Required before any permit can be filed
- Determines your final tank and drainfield sizing
- Works across NMED and county-permitted jurisdictions
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Frequently Asked Questions
In New Mexico, this work is done by a licensed liquid waste professional or an approved installer specialist — not a general contractor or the homeowner, except under the limited homeowner self-installation qualification for a primary residence.
Requirements can vary, but if significant time has passed since your original test, or the drainfield location has changed, most permitting authorities will want current soil data before approving a design.
Most installers include site evaluation and design as part of a full installation or replacement quote, though some price it as a separate up-front step. Ask directly when you get connected with a professional.
Start with a real site evaluation
Every project begins here. Tell us about your property and we'll connect you with a qualified evaluator.
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