Lewis County Aerobic Septic System

If you’re here for “Service”, help planning and permitting a Aerobic Septic System in Lewis County, you’re in the right place. McNair Septic Design & Consulting is the leading contractor providing aerobic septic system design and consulting in Lewis County from our home base in Brush Prairie, Washington. We keep it simple: listen to your goals, look at the land, and turn it into a clear plan that meets county rules without the runaround. From the first call, you’ll know what’s happening, why it matters, and what comes next, no guesswork, no jargon, just a straight path from soil to approval.

When an Aerobic System is the Smarter Choice

Aerobic treatment shines on sites with challenging soils, limited space, nearby waterways, or higher treatment expectations. Think of it as adding oxygen to the process so wastewater is treated to a cleaner level before it reaches the septic drain field. For many Lewis County properties, an aerobic design is the difference between “maybe” and “approved.” Our job is to confirm fit, set clear expectations, and build a plan that performs year-round.

What the Process Actually Looks Like

We start on the ground, not on a form. A site and soils review, plus Perc Testing (Percolation Test) when needed, tells us how your property handles water in wet and dry seasons. From there, we size the tank, select treatment components, and design dispersal that matches your soil profile. Distribution, pump dosing, monitoring ports, alarms, we dial in details so the system is easy to service and built for longevity.

Prefer to compare options? We’ll show you how an aerobic septic system stacks up against a gravity septic system for your specific lot, costs, care, and long-term reliability, so you’re choosing with eyes open.

Paperwork Without the Pileup

Permits and inspections can slow projects that don’t have a guide. We handle the applications, the submittal package, and coordination with the county so you’re not stuck chasing signatures. Once you approve our bid, we move fast, often getting your design submitted in about two weeks, so your project keeps momentum. You’ll get plain-English timelines and updates, not radio silence.

Why Homeowners Keep Choosing McNair

• Depth of experience. Our family has been designing systems across Washington since the 1970s. That history shows up in smarter layouts and fewer surprises.
• Licensed and insured. Your design is created by a Washington State on-site septic designer and backed by full insurance.
• Independent advice. We don’t sell equipment, so our recommendations are brand-agnostic. The design serves your property, not a product catalog.
• All design services under one roof. Site and soil evaluations, Perc Testing, consulting, complete plans, septic drain field layouts, and coordination through approval.
• Clear communication. You’ll always know what’s happening, what we need from you, and what comes next.

A Design that Fits Your Property and Your Plans

Every aerobic septic system we deliver is built around your site’s contours, water use, and future plans (like an ADU or shop). We consider setbacks, reserve area, power needs for treatment components, and service access so that maintenance is straightforward. The result: a design that meets county requirements, respects your landscaping, and performs reliably over the long haul.

From First Call to Green Light

Ready to get your aerobic septic system moving? Tell us a few details about your property, soil, timeline, goals, and we’ll turn it into a clear, build-ready plan that covers percolation testing, design, the drain field, and county paperwork without the headaches. Use the quote request form on this page to get started, and we’ll follow up with a straightforward scope, price, and timeline so you can move ahead with confidence.