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 45 years the McNair family has been designing septic systems in and around Southwest Washington. 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 with a Bachelors of Science degree. After several years of managing a restaurant and 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 years working together. Three years after Cory began, Scott lost his battle with cancer.

In 2015, Andrew Winslow joined the team. Andrew graduated from Whitworth University with a Bachelors of Communication degree. Andrew brought with him a customer service background and a great work ethic.

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!