New Zealand Flax Root System

Question

Our New Zealand Flax grass (assuming that’s what it is) is growing on top of our septic system. It has gotten very large in the last 2 years (girth & height). Should we be concerned about the root system growing into our septic causing future issues?

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Answer 1

Europe's compendium of invasive plants says the roots can extend as far and wide as the plant itself with "stout orange roots" running parallel. In addition, roots run vertically and diagonally.
You may want to remove or transplant this beautiful plant and replace it with something with a shallower root system, just to be sure. Here's our article about this plant: https://www.gardeningknowhow.com/ornamental/foliage/new-zealand-flax/new-zealand-flax-plant-care.htm