Professional Septic System Design
At McNair Septic Design & Consulting, we provide tailored septic system design solutions for homes and properties across Clark, Cowlitz, and Lewis Counties. From site evaluations to full county permitting, our designs ensure long-lasting, efficient systems that meet all Washington State regulations.
Septic System Design in
Clark, Cowlitz, Lewis, Skamania, and Klickitat County
Designing a septic system is more than just meeting code—it’s about creating a reliable wastewater solution for your property’s unique needs. At McNair Septic, we’ve been designing systems across Vancouver, Battle Ground, Longview, Centralia, Castle Rock, and surrounding areas for three generations. Our team ensures that every system—whether a gravity, pressure distribution, mound, sand filter, aerobic, subsurface drip, Glendon Pod, or OSCAR II design—fits your site conditions, household size, and long-term goals.
We begin with a detailed site and soil evaluation to determine the best system for your property. Every design includes precise calculations, county-ready maps, and specifications that keep your project moving smoothly from bid to approval. Because we aren’t tied to any one manufacturer, our recommendations are unbiased and focused solely on what works best for your property and budget.
For homeowners in Clark, Cowlitz, and Lewis County, a proper septic system design means fewer headaches down the road. Our systems are built to last, ensuring safe wastewater treatment while protecting your land and investment. We take care of all county permitting, submittals, and inspections—so you don’t have to.
With lightning-fast turnaround—submittals in as little as 14 days—our process keeps your project on track. Whether you’re building a new home in Ridgefield, upgrading an older property in Washougal, or developing land in Centralia, we provide designs that are clear, compliant, and efficient.
We Handle Every Step of the Permit & Inspection Process
From applications to approvals, we take the stress out of dealing with county paperwork. You can relax knowing we manage all applications, permitting and inspections. This saves you time, confusion, and unnecessary delays.
Designs for All Manufacturers – Not Just the Ones We Favor
Unlike several of our competitors, we are not owners or distributors of any specific septic systems. This independence ensures our designs are driven solely by what is best for your property—not by product commissions or supplier kickbacks. Our goal is to provide you with the most effective, efficient, and cost-conscious septic solution tailored to your unique needs.
One-Stop for All Septic Design Needs
From site and soil evaluations, perc testing, consulting and designs we provide every design-related service under one roof. You’ll work with a single trusted partner instead of juggling multiple contractors.
Proven Process That Simplifies a Complicated System
We’ve refined our approach over decades to make septic design as simple and stress-free as possible. From your first call to final approval, our process saves you headaches, time, and money.
Ready for Septic System Design?
The Process
Planning
All we need is your parcel number or address to begin. We research your property in advance, gather details about your future plans, and may schedule a site visit or call. Any questions are addressed quickly to keep the process moving.
Soils Evaluation
Most projects start with a soil evaluation (perc test), the first step toward system approval. We handle everything—from digging and testing to county applications, fees, and paperwork—while keeping you updated every step of the way.
On-Site Septic System Design
After completing the soil evaluation, we quickly create a detailed, cost-effective septic design, typically within one to two weeks, that includes all calculations, maps, and specifications, while handling every detail of the submittal process for you.
Review and Permitting
Most counties allow up to three weeks to review septic designs and soil evaluations, though some return them sooner. Once approved, we’ll send you a copy and can also forward it to licensed installers so you can receive system bids.
Taking Care of You
We handle everything—even the required county as-built map—so your septic system is approved and recorded. With no complex contracts, we start right away and keep things moving. Consultations are always free, so call us anytime.
Support
We can assist you in finding reputable septic installation and maintenance companies that can service and maintain your new system.
Frequently Asked Questions About Septic System Design
How do I know which type of septic system is right for my property?
That depends on soil type, property size, slope, and county regulations. We handle a full soil evaluation and recommend the best-fit system—gravity, mound, sand filter, aerobic, or others.
How long does the septic system design process take?
Once you approve our bid, we typically complete the design and submit it to the county within two weeks.
Do you handle county applications and permits?
Yes, we manage the entire process—from paperwork and fees to county health department approvals—saving you time and frustration.
Can McNair Septic design systems for commercial properties?
Yes, we design systems for both residential and commercial sites across Clark, Cowlitz, and Lewis County.
How often should septic systems be inspected or maintained?
It depends on the system type. Conventional gravity systems usually require inspection every three years, while advanced systems like aerobic or drip designs may require annual or semi-annual inspections. Review your county's Environmental Health Department for more detailed requirements.
