We provide you with the best possible septic options and designs. Call us for perc testing and a soil evaluation before you purchase property to see what a new septic system will cost.

Qualified Team

We only hire the best in the business, so you can be sure you’re working with the best designers, builders and inspectors. It is not just the quality of the design, but the quality of the entire experience.

Forward Design

We create unique designs specifically for you. We promise to look at the details of how your system will be used and offer our best and most cost-effective recommendations to you.

Superior Support

We’re here for you – before, during and after. We are not set in our ways and we are happy to adapt to the needs of our clients under the county and state regulations.


For over 50 years the McNair family has been designing septic systems in Washington State. In 1972, Scott McNair began working for the Clark County Health Department. He left that position a few years later to begin his own on-site septic design company. Scott continued designing systems for the next 30 years.

In 2005, Scott’s son, Cory began working with him. Cory graduated from Northern Arizona University. After several years managing a restaurant, then a bank he was ready for a change. Working with family was a great privilege and one that was not taken for granted. They were able to enjoy several great years working together before Scott lost his battle with cancer.

Michael Dunning has been a lifelong Battle Ground Resident. He joined our team with some construction background and 25 year’s experience in the service industry. We saw someone who worked hard, loved to serve others and had a stroke desire to learn. Although he had no experience in the specific industry, we were confident he would learn fast. He has stepped in and done just that as a valuable member of our team.

Jackson McNair is a third generation McNair working for McNair Septic Design. Known for his strong work ethic and dedication, Jackson excels academically. While working, he gains practical experience and demonstrates exceptional attention to detail. Jackson’s friendly nature and involvement in extracurricular activities further showcase his well rounded character. With his drive and passion, Jackson is on track for a successful future.

Septic Design Experts Since 1975
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I just love my new septic system! I really couldn’t have picked a better company to work with. McNair Septic truly is the best!

We hired them to redesign the septic system for our office building. We’re so happy with the results they’re doing our other 5 locations as well!

We just broke ground on my new custom home and hired McNair to install our septic system.  The team has kept me very involved in the process – I can’t wait to see the finished project!