The Southern Highlands is celebrated for its mature trees, the ancient oaks of Bowral, the towering pines around historic properties in Berrima, the established natives on rural acreage across Wingecarribee. But those trees, once planted near a pool, can become the pool’s worst enemy over decades. Tree root intrusion is one of the most common reasons for structural pool damage in the Southern Highlands, and it’s a problem that tends to be underestimated until it’s extensive.
Quick Answer (BLUF)
Tree roots can crack pool shells, displace coping stones, break plumbing connections, and undermine pool fencing. Once roots have penetrated a concrete shell, structural repair is expensive and temporary, the roots continue to grow and the damage recurs. In most cases where root intrusion has caused significant structural damage, pool removal is the more cost-effective long-term solution than repair. Fibreglass shells can be lifted or deformed by root pressure. Concrete shells are cracked and undermined. Neither type responds well to ongoing root presence.
How Tree Roots Damage Pools
Tree roots follow moisture and nutrients. A swimming pool represents a consistent source of both, a large volume of water, and the nutrient-rich chemical environment around pool edges (fertiliser runoff, organic debris, decaying organic matter). Roots that find their way into the pool zone don’t leave voluntarily.
The damage progression typically looks like this:
Stage 1, Coping and surround damage (often the first visible sign): Roots expand under coping stones and surrounding paving, lifting and cracking them. This appears as uneven coping, gaps between coping and shell, or cracking in the surrounding concrete pad.
Stage 2, Shell wall cracking: Roots exert significant lateral pressure on pool walls from outside. Concrete walls crack along horizontal lines as roots push in from the sides. Fibreglass walls may bulge inward or the shell may be displaced out of level.
Stage 3, Plumbing damage: Underground inlet, return, and drainage lines running through the pool zone are crushed or displaced by roots. This appears as poor filtration, unexplained water loss, or wet patches near plumbing runs.
Stage 4, Floor undermining: Roots under the pool floor create voids as they grow. When roots die (or are killed by root treatment), the voids collapse, causing pool floor cracking, sinking, or complete failure.
Stage 5, Shell structural failure: In advanced cases, the pool shell no longer holds water or has shifted significantly out of alignment. At this point, pool restoration is rarely cost-effective.
Trees Most Commonly Associated with Pool Damage in the Southern Highlands
| Tree Type | Root Behaviour | Risk Level |
|---|---|---|
| Large deciduous oaks (English oak, pin oak) | Deep, spreading roots that seek moisture aggressively | High, very common in established Highlands properties |
| Willows | Extremely aggressive, deep moisture-seeking roots | Very high, should never be within 15m of a pool |
| Pines (radiata, Monterey) | Broad, shallow lateral root systems | Medium-High |
| Eucalypts | Variable, some species aggressive, some moderate | Medium, depends on species and age |
| Poplars | Shallow, extremely aggressive lateral spread | Very high |
| Cottonwoods / liquid ambers | Shallow lateral spread | Medium-High |
| Ornamental cherries / plums | Smaller root systems | Low-Medium |
Many Southern Highlands properties have established deciduous trees, English oaks, liquid ambers, elms, that were planted when pools were also installed in the 1980s and 1990s. Those trees are now at maximum maturity and root spread, which is why root damage to pools of that era is reaching a peak.
Repair vs Removal: The Cost Comparison
When tree root damage has been identified, the repair vs removal decision comes down to extent of damage, likelihood of recurrence, and total cost.
| Scenario | Typical Repair Cost | Likelihood of Recurrence | Removal Cost (Alternative) |
|---|---|---|---|
| Coping and surround damage only | $3,000 to $8,000 | High (if tree remains) | $15,000 to $30,000 (full removal) |
| Shell cracks + plumbing damage | $8,000 to $20,000 | Very high | Same |
| Significant shell displacement | $15,000 to $35,000+ | Certain without tree removal | Same or cheaper |
| Floor voids and failure | $20,000 to $40,000+ | Certain | Same or cheaper |
In most root damage scenarios beyond Stage 2, the repair cost approaches or exceeds the removal cost, and repair does not solve the underlying problem unless the tree is also removed (which introduces separate approvals requirements, discussed below).
Removing the Tree vs Removing the Pool
One obvious question: rather than remove the pool, why not remove the tree? The answer depends on several factors:
Tree Protection Orders (TPOs): Many significant trees in the Southern Highlands are protected by Tree Preservation Orders or are covered by Wingecarribee Shire Council’s tree management provisions. Removing a large, established oak or significant native tree may require a formal application with arborist assessment, and may be refused. The pool removal near trees and TPOs guide covers this in detail.
Heritage significance: Trees on or near heritage-listed properties may have independent significance and be very difficult to remove. See heritage-listed pool removal in the Southern Highlands.
Landscape value: A 40-year-old established oak or liquidambar provides significant landscape character that cannot be replaced on any reasonable timeframe. Some homeowners place higher value on the tree than the pool.
Cost: Removing a large mature tree professionally (safely, in a confined garden space) costs $2,000 to $10,000 for the tree alone, plus stump grinding and debris removal.
Root management after tree removal: Even after a tree is removed, roots in the soil continue to decay and create voids for several years. Root barrier installation doesn’t help retroactively once roots are already in the pool structure.
In many Southern Highlands situations, the most pragmatic path is pool removal (keeping the tree) rather than tree removal (keeping the pool).
Identifying Root Damage Before It’s Critical
Early identification prevents the worst outcomes. Signs of early tree root intrusion include:
- Coping stones that have lifted, shifted, or cracked along a consistent line
- Crack patterns in the pool shell that follow a direction consistent with tree root growth
- Unexplained water loss beyond normal evaporation
- Roots visible emerging through pool shell cracks or tile joints
- Soft or hollow-sounding areas under surrounding paving
If you notice these signs, get a pool inspector (or your removal contractor during a site inspection) to assess whether root intrusion is the cause. Early action, when the damage is at Stage 1 or 2, gives you more options.
Pool Removal in the Presence of Large Trees
If you decide to remove the pool (with the tree remaining), the contractor must take care not to damage significant tree roots during excavation. This may involve:
- An arborist assessment of root zones before excavation
- Hand-digging near significant root zones rather than machine excavation
- Root pruning at a safe distance from the tree trunk
- Adjusting the excavation boundary to avoid major structural roots
The pool removal near large trees guide covers the arborist and construction requirements in detail.
Frequently Asked Questions
How do I know if my pool damage is caused by tree roots? The characteristic signs are cracking that follows a consistent direction (rather than random shrinkage cracking), displacement of the pool shell from its original position, and lifting of coping along a line adjacent to a large tree. A pool inspector can confirm root intrusion by inspecting crack patterns and sometimes using a camera in plumbing lines.
Can I repair a pool that has root damage without removing the tree? Structurally, yes, cracks can be patched, plumbing replaced, and coping relaid. But without removing or root-pruning the tree, the damage will recur as roots continue to grow. The repair is a short-term fix, not a long-term solution.
Does Wingecarribee Council allow tree removal to protect a pool? Council’s tree management provisions allow removal of trees that cause or are likely to cause structural damage to built structures, but this is assessed case-by-case. An arborist report confirming structural damage causation is typically required. This is not guaranteed to be approved for all tree/pool combinations.
What if the tree causing damage is on a neighbour’s property? Root encroachment from a neighbouring tree is a civil matter. You have the right (at your own cost) to prune roots at the property boundary. For pool damage claims from a neighbour’s tree, legal advice may be needed.
How long after pool removal can I plant in the old pool site? Immediately, once the site is backfilled and compacted. If the site was in the root zone of an existing tree, consider the tree’s moisture competition when selecting plants.
If tree root damage has compromised your pool, contact Southern Highlands Pool Removals for a free assessment and removal quote.