Before any pool removal can begin, the pool water must be removed. This sounds simple, drain the pool, wait for it to dry out, start demolition, but in the Southern Highlands context, dewatering requires careful planning. The region’s high groundwater table in many areas, its wet winters, and the legal constraints on where pool water can be discharged all make pool dewatering more involved than a homeowner might expect.
Quick Answer (BLUF)
Pool dewatering before removal in the Southern Highlands involves discharging pool water to the property’s sewer system (not stormwater), managing any inflow of groundwater during and after draining, and allowing adequate drying time before machinery work begins. In areas with high groundwater (parts of Moss Vale near the Wingecarribee River, valley floor properties near Kangaroo Valley, low-lying Robertson blocks), continuous pumping may be required throughout the removal process, not just before it starts.
Why Dewatering Matters for Pool Removal
A pool full of water weighs 50-100 tonnes (50,000-100,000 litres is typical for a standard 8m × 4m pool). Working with water still in the pool creates:
- Significant extra weight that complicates excavation and structural work
- Mud and slurry that makes working conditions dangerous and difficult
- Risk of water contamination spreading as the shell is broken
Additionally, an empty fibreglass shell in a high-groundwater area may “float” (pop out of the ground) due to buoyancy if the water table rises faster than the shell is weighted or removed. Dewatering strategy must account for groundwater as well as pool water.
Legal Discharge Requirements in NSW
Pool water cannot be discharged to:
- Stormwater drains, pool chemicals (particularly chlorine and salt) can damage aquatic ecosystems. NSW EPA regulations prohibit discharge of pool water to stormwater without prior neutralisation.
- Neighbouring properties, redirecting pool water onto an adjacent lot is a civil and potentially criminal matter.
- Watercourses, streams, drains, or rivers cannot accept pool discharge without specific approval.
The legal discharge pathway is to the property’s sewer connection (for properties connected to reticulated sewer). For most Bowral, Mittagong and Moss Vale properties, this means:
- Connect a submersible pump to the pool
- Run a discharge hose to the property’s laundry drain, bathroom drain, or direct sewer connection point
- Ensure the discharge rate doesn’t exceed the sewer’s intake capacity (slow and steady is better than maximum pump speed)
- Allow the pump to run until the pool is empty (typically 4-12 hours for a standard pool depending on pump capacity)
For properties on septic systems (most rural properties in the Highlands including Robertson, Kangaloon, Sutton Forest), sewer discharge isn’t available. In this case:
- Pool water must be treated (neutralised chlorine, pH balanced) before discharge
- Discharge onto the property’s own land (away from watercourses, bores, and septic fields) may be acceptable if the water is properly treated
- Very large volumes may require a licensed liquid waste contractor
The local authority (Wingecarribee Shire or Shoalhaven City Council) and NSW EPA should be consulted for properties on septic where large volumes of treated pool water need to be discharged.
Dewatering Methods
| Method | Description | Best Used For |
|---|---|---|
| Submersible pump (electric) | Electric pump lowered into pool, discharge hose to sewer | Standard residential dewatering |
| Petrol/diesel pump | Portable pump for off-grid or remote properties | Rural properties without easy power access |
| Sump pump | Smaller pump for final draw-down and groundwater management | Low-water levels, groundwater control |
| Pool pump (existing equipment) | Using the pool’s own filtration pump to discharge via backwash line | Functional pool equipment still operational |
| Gravity drain (if lower outlet exists) | Pool drains via existing drain fitting to outlet point | Pools with gravity-drain fittings installed |
For most standard residential removals in Bowral, Mittagong and Moss Vale, a submersible electric pump connected to the sewer line is the most efficient approach. Your removal contractor will typically handle this as part of the job.
Groundwater Challenges in the Southern Highlands
The Southern Highlands is not a dry area. Parts of Moss Vale, areas near Robertson, properties close to the Wingecarribee River, and Kangaroo Valley floor sites all experience high groundwater levels, particularly during winter and spring. This creates a specific pool removal challenge:
The float risk: An empty fibreglass shell in waterlogged ground is subject to significant upward hydrostatic pressure. If the pool is drained and groundwater rises around it before removal machinery arrives, the shell can be pushed upward out of the ground, a phenomenon known as “pool float” or “shell pop.” This is more common than many homeowners realise, particularly after heavy rain.
Mitigation strategies:
- Don’t drain the pool during active heavy rainfall events
- Coordinate pool draining to coincide closely with machinery arrival (drain on the afternoon before demolition starts, not a week before)
- Leave some water in the pool if there is a delay between draining and demolition start
- For known high-groundwater sites, specify continuous sump pumping during the removal process
The pool removal in winter guide discusses seasonal timing and groundwater considerations in more detail.
Managing Groundwater During Removal
Even after the pool water is removed, groundwater may continue to seep into the excavation during the removal process. This is particularly common in:
- Low-lying properties near watercourses in Moss Vale, Mittagong
- Robertson plateau properties in the high-rainfall escarpment zone
- Any site with clay substrate (clay holds water and releases it slowly)
Continuous sump pumping, keeping a submersible pump running at the base of the excavation throughout the removal works, manages this inflow. The contractor prices this as part of the job on known high-groundwater sites. On sites where groundwater isn’t expected but appears during works, it’s typically handled without additional cost.
Timing: How Long Before Removal Should You Drain?
| Site Condition | Optimal Drain Timing |
|---|---|
| Normal residential site, low groundwater | 12-24 hours before demolition starts |
| Known high groundwater site | 6-12 hours before demolition, with monitoring |
| Winter job in high-rainfall area | Drain on day of works, or leave water until machine arrival |
| Rural property on septic (slow discharge) | 24-48 hours to accommodate slower discharge rate |
Chemical Balance Before Discharge
Highly chlorinated water (especially from a pool that has recently been shocked with chlorine) should be discharged carefully. NSW Health and EPA guidance recommends:
- Allow chlorine to naturally degrade (leave uncovered in sun for 2-4 days) before discharge, where possible
- A chlorine level below 0.1 mg/L is generally safe for sewer discharge
- Extremely high chlorine levels (above 5 mg/L) should be treated with sodium thiosulfate before discharge
For a pool that has been sitting green and stagnant (high algae, potentially high metal levels), discuss with your contractor before draining, the sewer utility may have specific requirements.
Stormwater Drainage After Pool Removal
Once the pool is removed and the site backfilled, the drainage pattern of the property changes. See stormwater management after pool removal for how to design post-removal drainage correctly.
Frequently Asked Questions
Can I discharge my pool water to the street stormwater drain to speed up the process? No. Discharging chlorinated pool water to stormwater is illegal in NSW. The correct pathway is the property sewer for reticulated properties, or treated discharge to land (away from watercourses) for septic properties.
What happens if it rains heavily while my pool is draining? If heavy rain coincides with pool draining, monitor the site closely. Rising groundwater can cause the fibreglass shell to float before machinery arrives. If there’s a significant delay before works start, leave some water in the pool as ballast.
How long does it take to drain a standard pool? A standard submersible pump with a 25mm discharge hose will drain approximately 1,500-2,000 litres per hour. A 60,000-litre pool takes 30-40 hours. Using a larger pump (50mm discharge) can halve this time. Most contractors plan an overnight drain for standard pools.
Is dewatering included in the pool removal quote? Usually yes, dewatering is typically part of the pool removal service. Confirm with your contractor. On high-groundwater sites where continuous sump pumping is required throughout the job, this may be called out separately in the quote.
Does draining the pool before I engage a contractor cause any problems? Draining the pool without coordinating closely with your contractor risks the float issue (fibreglass shell popping up) if there’s any delay before removal begins. Better to coordinate the drain to happen just before the crew arrives.
Have questions about pool dewatering or ready to book a removal? Contact Southern Highlands Pool Removals for a free site inspection and quote.