What do I need to do to become a septic installer in Texas

Suggest you contact local licensing authority.

Hi Melvin

Click on this link I found at Google regarding Texas septic installers:

On-Site Sewage Systems (OSSFs), Including Septic Tanks (http://www.tceq.texas.gov/licensing/licenses/ossflic)

It should STEER (pun intended) you in the right direction... ;)

Mark