We won’t like: this blog might get a little bit . . . gross.
Drainage isn’t just an issue for plants and landscaping; it affects how we live in our homes as well. Most of us live in houses or other buildings that have a drainage system that moves waste water away from our toilets, sinks, and bathtubs and into either a sewer system or septic system of some sort. This generally happens via a main sewer line that connects the home we live in to the larger sewer or septic system. We may also have drains that move excess rainwater away from our homes and gardens via a French drain or similar construction. Most of the time these lines work quietly under the floors and underground, channeling waste or runoff away without our noticing. Sometimes they get clogged, however—and then we notice, in a hurry. A clogged sewer drain line can lead to waste water backing up the drains into our houses, which is a nasty situation indeed. So how does this related to gardening? Well, as it turns out, one of the primary causes of clogged drain lines is a blockages caused by tree roots growing into the line via a crack in the pipe. Left unchecked, this can lead to blockages, backups, breaks in the line, and costly repair bills. By understanding a bit about how our plants interact with the infrastructure of our homes, we can avoid these issues. So let’s dig in and learn a bit more about tree roots, sewer lines, and clogged drain pipes!
Tree Roots and Sewer Lines
We’ll start with the basic question first: how do tree roots invade sewer lines to begin with? The answer is rooted (pun intended) in the biology of how tree roots grow. Roots, the underground structures of the plant, perform two primary tasks: they anchor the plant in the soil and they gather nutrients and moisture that help the plant grow. Tree roots tend to grow quite large as they have more work to do due to the size of the tree. A good rule of thumb is that tree roots spread out two to four times further than the branches do. This isn’t an absolute rule but it’s a useful gauge of where the roots are likely to be.
Not all roots are big, heavy things. Many of them are small tendrils that soak up water and nutrients from the soil. These smaller roots are the initial problem for drainage, as they’ll find any gap or crack in a sewer line and grow into it. A residential sewer line can be paradise for tree roots—full of moisture, nutrition, and warmth. Under the right circumstances these roots grow rapidly, taking up more space in the drain line and widening the crack through which they enter. More roots follow and do the same, and a clogged drain results. For the folks living “upstream” this can lead to a big mess, huge inconvenience, and costly repairs.
So how do we keep the problem from happening in the first place?
Preventing Tree Root Intrusion into Drain Lines
Keeping tree roots out of drain lines or sewer lines is best done proactively. “An ounce of prevention is better than a pound of cure” as we’re fond of saying and it definitely applies here:
· Know where your sewer lines/drain lines are! As always, it all starts by understanding your garden space and known the lay of the land. It may take a little detective work to figure out where your sewer lines are: generally there’s an outside clean-out above ground that may provide some clues, or you can call your utility company to see if they can help. Locating your drainage lines of whatever sort is important regardless as it shapes everything we’ll do next.
· Plan—and plant—accordingly! As we mentioned earlier, tree roots can spread out pretty far, and even smaller shrubs and bushes can have surprisingly dense root networks. It’s best to plant trees and other landscaping plants a safe distance from your sewer lines to avoid infiltration and damage. It can be a pain and might alter your “perfect” landscaping layout, but it’s likely cheaper and easier in the long run and certainly far less messy than a backup.
· Create good drainage above ground! This may sound counter-intuitive, but bear with us. Tree roots grow where the moisture is; they’ll avoid dry soil. So by directing rainwater, run-off, and irrigation away from your sewer lines you can help steer roots away from them as well. There are a host of ways to do this: awnings and drainage around buildings can keep roots away from your foundation and your drain lines, hardscaping and ground cover can do the same for open spaces, and carefully watering or irrigating your landscape can direct roots in a safe directly. We generally recommending an “all of the above” approach for best results.
· Have you drain lines checked regularly, by a professional! Plumbers and landscapers know their business and they can perform checks and exams to assess the condition of your sewer lines, septic system, or drain lines and then recommend repairs or remediation as needed. Catching the problem early can make it much easier to fix, and while it’s a big beyond our scope as a gardening blog there are generally a number of possible options available.
On Nature, Humans, and Sewers
The interaction between tree roots and sewer lines or drain lines is, for lack of a better term, a bit yucky, but it’s also an interesting way to understand how natural spaces, garden spaces, and human needs intersect. We view sewer lines as a kind of gross necessity, best left underground and unseen. Tree roots respond to them as a gift, full of water, nutrients, and warmth. While we all need clear and functional drainage for health and safety, it is important to note that trees define “waste” differently than we do and respond accordingly. We’re part of the natural world, not in opposition to it, and we need to learn to work with nature in order to ensure that our homes work properly.
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