can i install the aquatru undercounter model myself or do i need a plumber?

You need a professional. It's not a DIY plug-and-play. The installation is a six-step turnkey process managed by Everpure. It starts with a site survey and water sample. They need to analyze your water to customize the filtration. The under-counter model has specific inlet (3/8" OD) and outlet (5/16" OD) lines that must be plumbed correctly. They also provide merchandising and training support. Call 800-323-7873 to start the process. Self-install voids support and likely won't work right.