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Why you should always avoid planting trees over sewer pipes

Establishing a beautiful garden can take many years and a lot of money, but if you plant your trees in the wrong place, you risk that money going down the drain. Literally!

One of the most common causes of blocked drains and sewer lines are trees with invasive roots. By the time you discover tree roots have damaged your drains, you may lose both the pipework and your tree. So spending a little time to plan your garden with sewer lines in mind can save you a lot of hassle and expense in the long run.


Dial before you dig

Take care to find out where your pipework and other utilities are located before you start digging, or you may destroy these well before your plants can. Call 1100 toll-free, or visit the Dial Before You Dig website to submit a free enquiry.


What to consider when planning your garden


How far can I plant trees from sewer lines?

There is no hard and fast answer here, however, the root systems of many trees are a similar width and depth as the branches and canopy. As a rough guide, check the size of the full-grown tree and make sure the distance from your pipes is at least equal to that of the tree’s height or spread.


Can I plant trees on a sewer easement?

An easement on your property grants access to your local council for any maintenance or repairs that may need to be done. Therefore, not only is it a bad idea due to the risk of blockages, it’s unlikely your council will permit you to plant trees on the easement at all.


Bay Tree


What are the best trees to plant near sewer pipes?

If you’re set on having trees in your garden and can’t entirely avoid sewer lines, then consider small trees with non-invasive root systems. Dwarf fruit trees, such as apple trees, can be a great option and provide fresh fruit too. Slow-growing trees can present fewer problems than fast-growing trees which can include a number of invasive species.

Attractive evergreen trees with non-invasive roots include:

  • Bay tree
  • Bronze Cottonwood
  • Coastal Golden Wattle
  • Feijoa
  • Olive tree

For a spectacular shade tree with a non-invasive root system, Japanese Maples are a great choice. This deciduous tree provides spectacular colour in autumn to give your yard wow-factor without damaging your pipework.

Alternatively, instead of a flowering tree, a shrub such an Azalea can add loads of colour and greenery to your garden.


Which trees should I be wary of?

Trees you should avoid planting anywhere near underground drainage pipes include:

  • Banksia
  • Birch tree
  • Bottlebrush
  • Camelia
  • Camphor Laurel
  • Citrus (lemons, limes, oranges)
  • Crepe Myrtle
  • Eucalyptus/Gum
  • Evergreen Alder
  • Figs
  • Frangipani
  • Hibiscus
  • Jacaranda
  • Liquidambar
  • Magnolias
  • Melaleuca
  • Oak tree
  • Pines
  • Poplar tree
  • Silver Maple
  • Wattle Acacia
  • Willow tree


Crepe Myrtle Tree in a front yard


How can I minimise the risk of damage from roots?

If you really want these trees in your garden, there are a few things you can do to protect your pipes.

Keep trees a good distance from your pipework – again, check the height of the fully-grown tree as a guide.

Replace old terracotta pipes – this material is subject to cracking and can be difficult to completely seal. New PVC pipework with pressure seals can prevent water from seeping into areas where root systems can seek it out.

Prepare your planting area with foresight – create a large, deep area of earth away from where pipelines are. Tree roots will follow the easiest path to moisture and prefer soil that is well-aerated and nutrient-rich, so encourage growth in the right direction.

Water deeply and regularly – if your trees are well-watered, they’ll have less need to take aggressive, invasive measures to find it.


Split drainage pipe caused by ingress of tree roots


Symptoms of a blocked drain

If you’ve bought a home with an established garden, you’ll inherit any of the trees and problems they might bring with them – including blocked drains. If you notice any of the following symptoms, it may be a sign you have a problem with tree roots:

  • unpleasant or “sewer” smells from drains
  • toilets that won’t flush waste away properly
  • outdoor drains overflowing
  • water taking a long time to drain away in sinks or toilets

Now is the time to call Chiswick Plumbing to investigate the cause of the blockage and take action! Chiswick Plumbing has a range of tools to thoroughly investigate and remedy blocked drains caused by invasive tree roots, or any other plumbing problems you may have.