Why Shouldn't Trees Be Planted Next to Underground Pipes?

Tree Roots and Water

• Tree roots don't usually go deeper than 2 to 3 feet below the surface. Most of the feeder root system grows horizontally a few inches beneath the soil surface and spreads up to three times farther than the longest branch of the canopy. Tree roots rarely damage intact pipes, but roots will take advantage of leaking water and any space created by cracks in the pipes. Tree roots will grow toward deteriorating water and sewer lines and irrigation pipes when they find water there.

Disturbance During Repair

• Occasionally it's necessary to dig lines up for repair. Site disturbance within the dripline of the tree -- the edge of the canopy -- can harm the tree. Mechanical excavation is a risk to the health and survival of a tree. If the tree is adjacent to an easement with underground utility lines, the roots could be damaged by work on the lines. Before you plant a tree, check for the location of underground services.

Call Before You Dig

• Hitting a line when digging the hole can cause service interruptions or a serious injury. Take necessary precautions to locate the lines. Utility companies often provide a service to locate and flag lines on your property. Ask your municipality for any markings or plans that show lateral piping for water and sewer locations nearby and connecting to the lines for your property. The information should also provide the depth of the underground pipes.

Planting the Tree

• Don't plant trees adjacent to underground pipes where excavation will disturb them. Consider the tree's size at maturity to reduce conflict with public easements and underground services. Avoid trees with shallow rooting systems that are especially responsive to water in the vicinity, such as willow, poplar, figs, rubber trees and large eucalyptus. After planting, install any underground pipes -- such as irrigation pipes -- where the tree won't be damaged by disturbance.