A method used to destroy existing roots in sewers and prevent regrowth for periods of 3 to 5 years is known as?

The method known to effectively destroy existing roots in sewers while also preventing regrowth for a duration of 3 to 5 years is referred to as root foaming. This technique involves the application of a herbicidal foam directly into the sewer lines, targeting the roots that intrude into the pipes. The foam adheres to the roots and is designed to kill them effectively while also creating a barrier to inhibit future growth.

Root foaming is particularly advantageous as it not only treats the immediate problem of root intrusion but also provides lasting effects that reduce the frequency of maintenance required. This longevity is crucial for preventing costly blockages and associated problems in sewage systems.

Other methods mentioned, like root removal and root cutting, typically focus on the physical removal of roots but do not offer the prolonged prevention of regrowth that foaming provides. Root encapsulation involves encasing roots, which may help manage their impact but doesn't effectively destroy them or prevent future growth as comprehensively as root foaming. Thus, the ability of root foaming to both eliminate the intrusive roots and deter their return makes it the preferred choice in this scenario.