Planting Guidelines for Municipal Sewer & Water Lines

General Guidelines

All trees should be planted no closer than 10 feet from sewer or water lines. When trees are planted more closely, the roots can grow into the sewer, causing backups and flooding. Not only is this plumbing nightmare expensive, but exposure to raw sewage can cause illness and disease.

Tree roots usually aren’t a problem in newer home developments that have sewer pipes made of PVC; however, clay pipes found in older areas are another story. These pipes develop small cracks over time, which leak nitrogen and water into the soil and allow roots to enter the pipes.

How far you plant a tree from a sewer or water line depends, in part, on the type of tree. Some water-loving trees have shallow, aggressive tree roots that can cause major problems. These types of fast-growing, thirsty trees, such as the ones list below, should be planted at least 20 to 30 feet away from sewer and water lines. The Ficus tree has a very aggressive root system and should never be planted near water or sewer lines. Although some large trees like oaks and maples grow more slowly, their roots can eventually invade sewer lines as well. The size of a tree’s root system is about the same as the size of the tree itself, so a large oak or maple’s roots can spread extensively under the earth, which is why they are on the Avoid List.

Plant trees that grow slowly and whose mature size will be small anywhere near sewer or water lines. If you already have fast-growing trees near the line, plan to replace them often, at a frequency of at least every ten years. Slow-growing trees will also eventually work their way into older sewer lines. The best option is to plant no trees near your sewer line, but if you want plantings near your sewer line, choose smaller ornamental trees or greenery, preferably shrubs. When planting, ensure that the trees have the nutrients and water they need to grow well. Amend soil with compost to improve texture and drainage, and water trees regularly, especially in the first year after planting. A healthy tree’s roots are less likely to grow into sewer lines.