Septic in Rio Arriba County, NM

Last updated: Mar 21, 2026

Rio Arriba County welcomes you with open skies, pine-clad mesas, and a long tradition of ranches and small farms tucked along winding roads. Here, wastewater planning isn't a one-size-fits-all city utility—it's about sensible on-site systems that work with our land, climate, and lifestyles.

Is septic common in Rio Arriba County? Should I expect septic if I own or buy a home?

Yes, septic is very common in many parts of the county, especially outside the towns with municipal sewer like Española or Chimayó. If your property sits outside an active sewer line, you'll likely have a septic system. If you're buying a home, plan for a septic-focused inspection and review any records the seller can provide—pumper receipts, maintenance history, and the permitting paperwork. A licensed septic inspector can confirm the system's condition and point out any upcoming maintenance needs.

Why homes typically use septic systems in Rio Arriba County

Rural layout and land use: Much of the county is spread out with larger lots, where extending centralized sewer lines isn't practical or affordable.
Soil and groundwater considerations: Local soils and seasonal moisture demand careful design, placement of the tank and drain field, and adequate separation from wells and springs.
Long-term affordability and reliability: On-site systems give homeowners predictable wastewater treatment without relying on distant pipes or costly trunk lines.
Local climate realities: Cold winters, freeze-thaw cycles, and variable precipitation require robust venting, frost protection, and proper drainage to keep systems healthy year round.

County growth history and how that has impacted septic coverage

Rio Arriba's story is one of steady, uneven growth. Early settlement was centered in ranching and agriculture, with towns growing along trade routes and railroad corridors. Over the decades, some towns expanded sewer service, but large swaths of rural Rio Arriba remain unsewered or served by local sewer districts that still depend on individual septic systems for many homes. As development crept toward dispersed subdivisions and second homes, the importance of proper septic design, regular pumping, and proactive maintenance grew. This history means most homes in the county rely on on-site treatment, and today's buyers and homeowners benefit from understanding septic health as part of everyday property care.

High-level explanation (why septic exists here)

On-site wastewater treatment is a practical, land-friendly solution that pairs well with Rio Arriba's rural character, environmental sensitivities, and the cost of expanding centralized sewer. It's a reliable way to protect groundwater, streams, and property values while keeping homes comfortable and self-sufficient.

How Septic Is Regulated in Rio Arriba County

Regulatory framework in Rio Arriba

In New Mexico, on-site wastewater systems (septic) are governed by the state through the New Mexico Environment Department's OWTS program. Rio Arriba County enforces those rules locally via its Environmental Health Office, ensuring new systems, major repairs, and replacements meet state standards. Permits are typically required, and installations must be done by licensed professionals with inspections at key milestones.

Who regulates and what that means for homeowners

State role: The OWTS program sets design, installation, and performance requirements that every septic system must meet.
County role: Rio Arriba County adds jurisdictional oversight, schedules inspections, and confirms work complies with local health codes.
Your responsibility: Obtain the proper permit, use a licensed installer, and keep records of inspections and maintenance.

Permits, design, and inspection timeline (step-by-step)

Confirm permit requirements with your local office
Contact the Rio Arriba County Environmental Health Office (or the state OWTS program) to confirm whether your project needs a permit and which agency will issue it.
If in doubt, start with the county office; they can point you to the correct authority.
Get a site evaluation
A qualified professional should assess the property, soil, and drainage to determine the appropriate septic system type and size.
The evaluation helps ensure the system will function properly for long-term use.
Prepare and submit the design
Have a licensed OWTS designer or professional engineer prepare a system design that meets state and local requirements.
Submit the design package along with the evaluation to the issuing authority for approval and permit issuance.
Install with a licensed contractor
Use a licensed septic installer to install the system per the approved design.
Schedule inspections at critical milestones (e.g., after trenching, after plumbing rough-in, and after final installation) as required by the inspector.
Pass final inspections and receive approval
The inspector verifies that the system is installed according to the approved plan and code.
Keep the final approval and all permit documents in your records.

Installation and inspection best practices

Always hire licensed professionals recognized by NM state or Rio Arriba County for OWTS work.
Maintain good access to the system's components for future maintenance or pumping.
If you're buying or selling a home, expect an OWTS disclosure and potential transfer inspections.

Maintenance and long-term care

Schedule regular pumping and inspection intervals (typical guidance is every 3–5 years, depending on usage, tank size, and household water load).
Use septic-safe products and limit chemical cleaners that can disrupt the tank's microbial balance.
Protect the drain field: keep vehicles and heavy equipment off the area, plant only grass, and prevent surface water pooling.

Signs of trouble and immediate steps

Signs: gurgling sounds, slow draining, sewage odors, wet spots or lush grass over the drain field, or sewage backups.
Action: Do not pour fats, oils, or non-biodegradable materials down drains; contact your septic professional and the local health office promptly.

Resources and where to get official help

State resource: New Mexico Environment Department – On-Site Wastewater Treatment Systems (OWTS)
- Official site:
For county-specific guidance, contact the Rio Arriba County Environmental Health Office to confirm local procedures and inspection scheduling.

Soil, Groundwater & Environmental Factors in Rio Arriba County

Soil Types and Infiltration in Rio Arriba County

Rio Arriba County sits on a mix of valley alluvium, upland loams, clays, and patches of fractured bedrock. Permeability can swing from well-drained sandy loams to slow-draining clays, with cobbly or rocky subsoils in higher elevations. A shallow bedrock layer or dense clay can create a perched or limited absorption zone, reducing the effective area for septic effluent to percolate. When soils are shallow or fractured, alternative design approaches may be necessary to protect nearby wells and surface water.

Look for soil texture changes (sand, silt, clay) and how deep you'd need to reach suitable absorption.
Observe for perched water or mottling in the upper soil horizon, which signals seasonal moisture variation that affects drainage.
Schedule a professional soil investigation as part of your septic design.

Groundwater Depth, Quality & Contamination Risk

Groundwater depth in Rio Arriba County varies a lot by site, with some areas having shallow wells and others tapping deeper aquifers. High or fluctuating water tables, especially in valley bottoms during spring runoff, can reduce the available vertical separation between septic components and groundwater. Poorly sited systems in permeable soils or near watercourses pose a higher risk of effluent reaching groundwater or surface water. If your household relies on well water, extra care is warranted to prevent contamination.

Before designing or installing a system, check local groundwater depth data and well logs through county or state resources.
If your property sits near streams, springs, or known fracture zones, plan for enhanced separation distances and protective features.
Consider periodic groundwater testing if you already have a septic system and a well as your drinking water source.

Seasonal & Environmental Factors Affecting Septic Performance

Rio Arriba's desert-to-montane climate brings wide seasonal shifts that influence septic performance. Freeze-thaw cycles, drought, and variable precipitation change soil moisture and pore space, which in turn affect effluent movement and treatment.

In winter, frozen soils slow infiltration and can pressurize underground components; ensure adequate frost protection and proper installation depth.
Drought reduces groundwater pressure and can alter the position of the water table, affecting leach field efficiency. Water conservation becomes part of maintaining system longevity.
Seasonal storms can temporarily saturate soils; design and maintenance should anticipate short periods of higher-than-average moisture.

Design Implications for Rio Arriba County Homes

With diverse soils and groundwater conditions, a one-size-fits-all septic solution rarely works. The key is aligning site conditions with an appropriate system type and precise maintenance plan.

If soils are deep and permeable with stable groundwater, conventional septic systems may work, but still require proper setbacks and features.
If soils are shallow to bedrock or have high clay, mound systems, sand filters, or pressure-dosed leach fields may be better options.
In areas with close wells or limited absorption capacity, enhanced treatment (pretreatment, raised systems) and stricter setback compliance are important.

Practical Steps for Homeowners

Obtain a professional site and soil evaluation from a designer familiar with Rio Arriba conditions.
Verify depth to groundwater and presence of bedrock or restrictive layers on your lot using local logs and NRCS/USGS resources.
Plan for conservative design margins and, where needed, alternative absorption methods (e.g., mound or sand-based systems).
Implement water-saving practices to reduce effluent volume and protect soil moisture balance.
Schedule regular system inspections and pump-outs, especially in areas with seasonal moisture fluctuations.
Official resources:
- New Mexico Environment Department (OWTS) – Onsite Wastewater Treatment Systems:
- U.S. EPA – Septic systems:

Typical Septic System Types in Rio Arriba County

Conventional gravity septic systems

A conventional gravity system is the workhorse for many Rio Arriba County homes with suitable soil. Wastewater from the house enters a septic tank, where solids settle. Liquids then drain by gravity into a buried drainfield or leach field. The soil beneath and around the drainfield cleans the effluent before it returns to the groundwater.

How it works: Tank separates solids; effluent flows by gravity to perforated pipes in trenches.
Site requirements: Adequate soil depth, permeability, and room for trenches.
Pros: Simple design, generally lower upfront cost, reliable when soil conditions are right.
Cons: Performance declines with restrictive soils or high groundwater; improper loading or tree roots can disrupt the field.

Low-Pressure Dose (LPD) systems and pressure distribution

When soil conditions are marginal or the drainfield is shallow, a pressure-dosed approach helps distribute effluent evenly across trenches.

How it works: A pump delivers small doses of effluent to multiple irrigation lines in a controlled sequence.
Site requirements: A smaller footprint may be possible; needs reliable power and a control system.
Pros: More even distribution, can work in soil that wouldn't support a conventional gravity field.
Cons: Slightly higher maintenance; more components that can fail.

Mound systems

Mounds are raised drainfields built above the native soil, used when the native soil is too shallow, too permeable, or has a high water table.

How it works: A gravel or sand bed is built, with a dosing system feeding effluent into perforated pipes at the top of the mound.
Site requirements: A suitable footprint and space for the mound materials; proper grading to manage surface water.
Pros: Enables septic use in challenging soils; often effective where conventional fields won't work.
Cons: Higher construction cost; more to inspect and maintain.

Sand filters and evapotranspiration (ET) beds

These systems treat effluent further using intermittent filtration or evaporation through the root zone, useful in challenging soils or when additional treatment is needed.

How it works: Effluent from the tank passes through a sand filtration layer or into an ET bed where plants use water and help remove contaminants.
Site requirements: Adequate space and appropriate climate; routine vegetation management.
Pros: Higher treatment capability; can extend the life of a drainfield in tough soils.
Cons: More components to monitor; climate and plant maintenance influence performance.

Advanced treatment units (ATUs) and packaged systems

For homes needing higher quality effluent or dealing with stricter local requirements, ATUs provide additional treatment before discharge.

How it works: A compact, factory-built treatment unit performs biochemical treatment; effluent then flows to a drainfield or reuse system.
Site requirements: Space for the unit and often a connection to an irrigation or reuse setup.
Pros: Improved effluent quality; can permit smaller or alternative drainfields.
Cons: Higher upfront and ongoing maintenance costs; requires service by qualified installers.

Other options and local considerations

Rio Arriba County properties sometimes use hybrid approaches or supplemental reuse where permitted and feasible. Always verify with the local health department and a licensed OWTS designer.

ET beds and sand filters may pair with drip irrigation where local codes allow.
Proper setbacks, groundwater protection, and landscape planning are essential.

Step-by-step: evaluating options for your property

Get a professional site assessment: soil permeability, depth to groundwater, slope, and available space.
Compare drainfield options based on soil tests and local codes (NMED OWTS guidance is a good starting point).
Consult a licensed septic designer or installer who understands New Mexico requirements.
Review maintenance needs and long-term costs for conventional vs. alternative systems.

Maintenance considerations

Schedule regular pumping (frequency depends on tank size and household use).
Inspect annually for standing water, soggy soils, gurgling sounds, or strong odors.
Keep system components accessible and protect drainfield from heavy loads or pesticide exposure.

Learn more from official resources:

EPA septic systems overview:

Typical Septic Issues Across Rio Arriba County

Common signs of trouble

Slower drains, frequent clogs, or gurgling noises from pipes.
Sewage odors around the house, yard drains, or the septic tank cover.
Wet, soggy spots or lush, unusually green patches over the drainfield.
Backups into sinks, toilets, or tub drains, especially after heavy rainfall or running water.
unusually high water usage for your family or visible pooling on the drainfield.

These signs often point to trouble with the septic tank, the drainfield, or the connections between them. Don't ignore them: early attention can prevent costly damage and groundwater concerns.

Local soil and site conditions in Rio Arriba County

Rio Arriba soils vary from rocky and shallow to clay-rich and slowly permeable, which can complicate leach-field performance.
Elevated bedrock, high water tables near rivers, and seasonal monsoon moisture can lead to inadequate effluent absorption.
Sloped sites or compacted soils reduce drainfield effectiveness and increase surface runoff risks.
Small lots or homes with multiple bedrooms typically generate more wastewater, stressing the system more quickly if the drainfield isn't sized or maintained properly.

Understanding your site helps you spot when a system is under stress and what kind of repair it needs.

Common failure modes by system type

Conventional septic tanks with gravity-leach fields: soil absorption issues, root intrusion, and blocked effluent paths cause backups and odors.
Mound systems: designed for high water tables or poor soils; prone to clogging if maintenance is skipped or groundwater rises.
Drip or effluent-distribution systems: pipes can clog or be damaged by roots, leading to uneven wastewater dispersal.
Pumped systems (alternating or pressure-assisted): pump failures or control valve problems disrupt flow and can cause standing effluent.

Routine checks help catch these issues before a total failure.

Maintenance gaps that cause problems

Infrequent pumping: many homes in Rio Arriba County need pumping every 3–5 years, depending on tank size and household use. Pumping too rarely allows scum to overwhelm the tank, increasing the risk of solids entering the drainfield.
Skipping inspections after heavy rains or droughts: groundwater level changes affect performance and can hide problems.
Ignoring septic tank filters or baffles: clogged filters slow flow and promote solids buildup.
Using too much water or disposing non-biodegradables, fats, oils, and greases down drains: these overload the system and clog the drainfield.
Landscaping over the drainfield: heavy equipment, digging, or dense root activity can damage pipes and reduce absorption.

Practical steps if you notice a problem

Limit water use until you know more: space out laundry, dishes, and showers; avoid running garbage disposal frequently.
Check for obvious issues: odors, back-ups, soggy areas, or gurgling sounds.
Schedule a licensed septic professional assessment: they can perform an inspection, pumping if needed, and field evaluation.
Consider a drainfield evaluation or dye test to pinpoint where issues lie, and discuss remediation options with a pro.
Keep records of maintenance, pump dates, and any repairs to help future service visits.

When to involve official resources

If you suspect contamination of a well or nearby water source, contact local environmental health authorities and your state agency for guidance.
For general guidelines and regulatory standards, consult official resources:
- U.S. EPA Septic Systems:

Septic Inspection, Permits & Local Oversight

Who oversees permits in Rio Arriba County

In Rio Arriba County, onsite wastewater systems are overseen through a mix of county departments (often Environmental Health or Planning & Zoning) and state agencies. The goal is to ensure systems are designed, installed, and maintained safely and in compliance with local and state standards.
Start by checking with your county department for the exact process and point of contact. You can also review NM state guidance for onsite wastewater to understand design and inspection expectations.
Official resources:
- Rio Arriba County website and departments:
- Rio Arriba County Environmental Health, if available: https://www.rioarriba.org/department/environmental-health
- New Mexico Environment Department (state-level guidance): https://www.env.nm.gov

When a permit is required

A permit is typically required for:
- Installing a new septic system
- Replacing an existing system or making substantial upgrades
- Reworking the drain field layout or tank placement
- Moving or expanding a structure that affects the septic system
Permits ensure the design meets local zoning, setbacks, soil suitability, and state technical standards.
If you're purchasing a home, a permit-history check or a septic-system inspection may be requested as part of the transfer process.

How to apply for a permit

Confirm the appropriate issuing office (county Environmental Health or Planning & Zoning) and obtain the permit packet.
Gather essential information:
- Land ownership and lot size
- Soil data or percolation test results (if available)
- Proposed system design including tank size, number of bedrooms, and drain-field layout
- Location maps and property setbacks
Complete and submit the permit application with any required fees.
Submit engineering plans or a system design prepared by a licensed designer or professional, if required by your jurisdiction.
Schedule any required pre-approval meetings or site visits with the review office.
Await plan review outcome and respond to any requested corrections.
Helpful reminder: follow up with the issuing office if you don't hear back within the stated review window.

Inspections you may encounter

Inspections are typically required at key milestones:
- Pre-installation site evaluation
- During construction (tank placement, backfill, and trenching)
- Final installation inspection (system is operational and meets design)
- Post-installation verification or certification of compliance
Inspections ensure the system is installed per approved plans, local codes, and state standards.
If issues are found, you'll usually be given a correction notice with a deadline to address them.

For home sales and transfers

A septic inspection or certification may be requested during a house sale.
Expect a licensed inspector to verify the system's condition, capacity, and code compliance.
If the system is failing or non-compliant, remediation or upgrades may be required before closing.

Finding help, inspectors & official resources

Start with the county's official channels for the most accurate guidance on permits and inspections.
Consider contacting a licensed onsite wastewater designer or septic contractor who understands local requirements and can prepare designs that meet both county and state standards.
Official resources:
- Rio Arriba County: https://www.rioarriba.org
- Rio Arriba County Environmental Health (if page exists): https://www.rioarriba.org/department/environmental-health
- New Mexico Environment Department – Onsite Wastewater / Septic Guidance: https://www.env.nm.gov/water-quality/onsite-wastewater/

Quick reference steps (summary)

Step 1: Verify permit needs with the county.
Step 2: Collect design, soil, and site information.
Step 3: Submit permit application and pay fees.
Step 4: Complete required inspections at each milestone.
Step 5: Obtain final certification of compliance before use (or for sale, as required).

Cost Expectations for Septic Services in Rio Arriba County

Septic Tank Pumping and Maintenance

What it includes: removal of accumulated sludge and scum, cleaning of the tank interior, inspection of inlet/outlet baffles, checking the effluent screen (if present), testing basic system function, and confirming access ports are clear. In Rio Arriba County, many homes are older or on hillside lots with variable tank ages, so crews may also assess tank condition and seal integrity.
Rio Arriba specifics: remote properties and winter weather can affect scheduling and add travel time; some older systems use cesspools or smaller tanks—pumping helps prevent premature field failure.
Typical cost in Rio Arriba County: $250–$600 per service visit. Travel fees and extra labor for clearing difficult access can add $50–$150.

Septic System Inspections

What it includes: visual inspection of tanks, lids, and baffles; assessment of drain field performance; measurement of soil absorption; pump or aerator checks if applicable; and, when needed, dye or flow tests to verify functionality.
Rio Arriba specifics: inspections are common during home purchases or renovations; rural properties may require more travel time and longer inspection windows in winter.
Typical cost in Rio Arriba County: $100–$350, often $150–$300 for standard inspections without extensive testing.

Drain Field Evaluation and Soil Testing

What it includes: soil evaluation, percolation or infiltration testing, assessment of drainage trenches or beds, and recommendations for field layout or alternative systems if soils are marginal.
Rio Arriba specifics: clay or rocky soils, shallow bedrock, and variable groundwater can necessitate deeper trenches, mound systems, or alternative designs; weather and access can influence testing time.
Typical cost in Rio Arriba County: $300–$900, commonly $350–$700 for typical residential evaluation.

Drain Field Repair and Replacement

What it includes: repairing damaged trenches or distribution lines, replacing failed lateral lines, restoring proper moisture distribution, and may involve soil remediation or added soil cover.
Rio Arriba specifics: challenging terrain and soil conditions can drive higher material and trenching costs; some sites require permits or soil amendments that add time and expense.
Typical cost in Rio Arriba County: $2,500–$12,000, with broader ranges if full replacement or mound systems are needed ($8,000–$20,000+ in tougher sites).

Septic System Repairs (Non-Tank)

What it includes: fixing leaks, addressing cracked lids, baffles, or damaged pumps; repairing or replacing submersible pumps or alarms; repairing leachate lines or backflow issues.
Rio Arriba specifics: repair accessibility can affect labor time; remote homes may incur additional travel and out-of-area service calls.
Typical cost in Rio Arriba County: $150–$3,000, depending on the problem and parts required.

Septic System Design and Installation (New Systems)

What it includes: site evaluation, system design tailored to soil and slope, permitting assistance, installation of tank, distribution and drain field (or mound/alternative systems as needed), and start-up testing.
Rio Arriba specifics: remote locations, cold winters, and soils with limited absorption may require more robust designs and longer installation timelines; permitting through NMED and local channels is common.
Typical cost in Rio Arriba County: $6,000–$25,000+, with larger or more complex sites (mound or advanced treatment units) at the higher end.

Cesspool Decommissioning and Old System Abandonment

What it includes: safely sealing and decommissioning old cesspools or abandoned tanks, removing sludge, filling with approved material, and ensuring the site is clearly marked.
Rio Arriba specifics: many older properties in the county still operate cesspools; proper decommissioning is often required during property transfers or major upgrades.
Typical cost in Rio Arriba County: $2,000–$6,000, depending on access and depth, plus any permit costs.

Pump/Alarm Service and Replacement

What it includes: checking and servicing effluent pumps, float switches, alarms, and wiring; replacement of failed components.
Rio Arriba specifics: electrical access and weather exposure can influence repair time and parts availability.
Typical cost in Rio Arriba County: $200–$1,500, depending on pump type and labor.

Steps to plan service

Confirm access and any weather-related scheduling constraints for your property.
Request a written estimate that includes travel time and any potential permit or disposal fees.
Have a licensed septic professional assess tank age, soil conditions, and drainage status.
Schedule regular maintenance based on usage, household size, and local soil conditions.

Official Resources

New Mexico Environment Department – Onsite Wastewater Program:
U.S. EPA – Septic Systems:

Septic vs Sewer Across Rio Arriba County

Availability and service areas in Rio Arriba County

In rural parts of the county, private septic systems are the norm because municipal sewer lines don't reach every property.
In incorporated towns and some subdivisions, municipal or regional sewer service is available. If you're unsure whether sewer is in your area, contact your local town or county public works department or the sewer utility to confirm service boundaries and any connection requirements.

Septic systems: Pros and Cons

Pros

Lower ongoing costs when you don't use municipal sewer.
Works where there is no sewer line nearby.
More independent control over wastewater treatment on private property.

Cons

Requires proper sizing, installation, and soil conditions; mistakes are costly.
Regular maintenance needed (typically pump every 3–5 years; inspect components annually).
Failure or misuse can contaminate groundwater and septic fields, especially in soil with poor drainage.

What to expect

Typical setup includes a septic tank, distribution box, and leach field or drain field.
Local code and state rules govern installation, permitting, and pumping intervals. See state guidance below.

Municipal sewer: Pros and Cons

Pros

Wastewater is handled by a centralized system, reducing homeowner maintenance.
Predictable monthly costs via a sewer bill; no septic tank to pump or field to fail.
Fewer on-property environmental risk if properly managed.

Cons

Connection costs can be high (one-time hookup fees, possible system upgrades).
Monthly sewer charges add to ongoing housing costs; rates vary by utility.
If the sewer system clogs or backs up, you rely on the utility to fix it and may be temporarily impacted.

What to expect

If you live within a town's sewer service area, you'll be billed by the local utility and must connect when required by code.
When connecting, you typically decommission the septic system following local and state guidelines.

Is sewer available where you live? How to check (quick guide)

Verify service maps with your town or county public works department or the sewer authority.
Request a connection quote, including any impact or tap fees.
If sewer is not available, ask about planned expansion timelines and intermediate wastewater options.
If you plan to stay on septic, ensure the system is properly designed, installed, and permitted, per state guidelines.

Maintenance and regulatory considerations

Septic users: keep records of pumping, inspections, and system upgrades; follow NMED's On-site Wastewater Treatment Systems (OWTS) guidance.
If you switch to sewer: hire a licensed professional to decommission the septic tank properly and remove or abandon related components to code.
Regular inspections help prevent failures—look for soggy areas, odors, backups, or system surges after heavy rainfall.
Always use septic-safe products and minimize solids entering the system; avoid pouring oils, chemicals, or non-biodegradables into the system.

Costs and financing: quick comparisons

Septic system installation and up-front work: roughly a few thousand to well into the tens of thousands, depending on soil, lot size, and permit requirements; ongoing maintenance adds up over years.
Sewer connection: one-time hookup costs plus ongoing monthly sewer charges; the total depends on the utility's fee structure and any required system upgrades.
For both options, plan for inspections and permits as part of the project. State and local requirements apply.

Quick action steps

Confirm sewer availability for your property with the local public works or sewer utility.
If using septic, schedule a professional assessment and obtain required permits; keep maintenance calendars.
If connecting to sewer, obtain a quote and understand decommissioning requirements for the septic system.
Consult official guidance for on-site systems and septic compliance:
- New Mexico Environment Department (OWTS):
- EPA septic systems overview: https://www.epa.gov/septic

Resources

New Mexico Environment Department - On-site Wastewater Treatment Systems (OWTS): https://www.env.nm.gov/owts/
EPA – Septic systems: https://www.epa.gov/septic