Tree roots cause more damage to Canberra’s underground infrastructure than most homeowners realise. Icon Water recorded over 1,900 sewer main breaks and blockages in the ACT in 2024-25 — a dramatic increase on the previous year, with dry autumns and winters driving roots deeper in search of water. The trees most likely to be responsible are not obscure species — they’re the ones growing in many Canberra backyards right now. Here’s a guide to the most common offenders and what you can do about them:
- Eucalyptus (gum trees). Canberra’s most iconic tree is also one of its most problematic near structures. Eucalyptus roots are shallow, lateral and extremely wide-spreading — capable of extending 30 metres or more from the trunk. They are well-documented for lifting footpaths, cracking driveways and infiltrating sewer and stormwater pipes, particularly older clay or terracotta systems. Even medium-sized gum trees should be kept at least 10–15 metres from any underground service.
- Poplars (including Lombardy and White poplar). Extremely common in older Canberra suburbs and along waterways, poplars combine fast growth with an aggressive, water-seeking root system that travels remarkable distances. They are notorious for blocking pipes, lifting paving and destabilising foundations by drawing moisture unevenly from soil. White poplars also sucker freely — new shoots can emerge metres from the original trunk for years after removal.
- Liquidambar (sweet gum). One of Canberra’s most planted street and garden trees thanks to its spectacular autumn colour — but its fast-growing, aggressive root system is well-documented for clogging stormwater pipes and lifting driveways. Beautiful in a large garden or park; risky planted close to any infrastructure. Keep a minimum of 8–10 metres from pipes and hard surfaces.
- Silver birch (Betula pendula). A popular ornamental choice for Canberra gardens, silver birch has a wide, shallow, flat root system that spreads far beyond the canopy and sits close to the surface. This makes it particularly likely to lift paving, crack driveways and interfere with shallow pipes. Because the damage is surface-level, it often appears sooner than with deeper-rooted species.
- Plane trees (Platanus). Widely planted as street trees in older Canberra suburbs, plane trees were specifically identified by the ACT Government in 2019 as having aggressive root systems that damage pavement and infrastructure. They are now planted ‘sparingly’ by the ACT Government for exactly this reason.
- Wattles and acacias. While celebrated as Australian natives, many acacia species have aggressive surface root systems. Fast growth means damage can occur relatively quickly — particularly to driveways, pathways and shallow drainage. Some species also have a short lifespan and can become structurally unstable, posing a dual risk of root damage and limb failure.
Having one of these species in your garden doesn’t automatically mean you have a problem — distance, soil type, pipe condition and tree age all factor in. The key questions are: how close is the tree to your infrastructure, how old are your pipes, and are there already signs of root activity (slow drains, lifting pavers, damp patches)?
Plant birch trees well away from infrastructure.