How to Drain a Pool Safely and Legally Before Removal

Knowing how to drain a pool before removal in NSW means more than pointing a hose at the garden: you need to neutralise the chemistry, choose a legal discharge point, manage the risk of a concrete pop-out or fibreglass float, and coordinate the timing with your contractor. Our companion guide on pool water disposal costs in NSW covers the fees and consent requirements in detail; this guide focuses on the practical steps of the drain itself. The NSW EPA water pollution page sets out why unlawful discharge carries real penalties.

Before you drain: check chlorine, salt and pH

Before pumping out a litre, you need to know what is in the water. Most pool water contains residual chlorine, and salt-chlorinated pools carry dissolved sodium chloride at concentrations that are not acceptable to stormwater drains.

Pre-drain checklist:

To bring free chlorine down: stop dosing, run the pool in full sun for several days, or add sodium thiosulphate (dechlorinator) at the rate specified on the packaging. For salt pools, dilution with mains water reduces TDS, but increases the total volume you need to dispose of.

Test the water yourself with a test kit, or have the pool shop run a sample. Keep the test results in case Hunter Water or council asks for evidence of pre-treatment.

Contact Hunter Water trade waste to confirm current discharge consent requirements before you pump. Their requirements are authoritative; this guide is not legal advice.

Concrete pop-out risk: why empty pools crack

An in-ground concrete pool shell acts as a large rigid vessel in the surrounding soil. When the pool is full of water, that weight helps keep the shell in place and resists the upward pressure of any water-saturated soil around it.

When you empty a concrete shell, the upward pressure from saturated soil or a high groundwater table can overcome the shell’s own weight. On clay-dominant or poorly drained sites this can cause the shell to lift or crack, particularly at the floor or corners. This phenomenon is sometimes called a pop-out or blowout.

The risk is highest when:

• The water table is high (common near the lake, near the Hunter or Paterson rivers, or in low-lying flood-plain areas).
• The shell has pre-existing cracks that allow water to enter the concrete and reduce its effective weight.
• Heavy rainfall occurs immediately after draining.

Practical measures:

• Drain just before demolition, not weeks ahead.
• If rain is forecast in the 24 hours before or after draining, consult your contractor before proceeding.
• On low-lying or river-adjacent blocks, ask your contractor whether a pre-drain geotechnical check is worthwhile.

Our guide on wet weather and pool removal delays covers related timing risks.

Fibreglass float risk: why shells lift

A fibreglass pool shell is much lighter than a concrete one of the same size. An empty fibreglass shell can weigh as little as 1.5-3 tonnes. When groundwater pressure underneath the shell exceeds the shell weight, it can lift out of the ground, sometimes dramatically.

This is not a hypothetical: in areas near Lake Macquarie or the Hunter River, shallow water tables can sit close to or above the base of the pool. Our fibreglass pool removal service covers how this is managed.

Do not leave a fibreglass pool empty overnight without engineering advice if you are near water or in a low-lying area. The consequences of a floating shell are significant: the shell can crack, distort or damage surrounding structures.

If you must pre-drain a fibreglass pool before your contractor arrives, drain it on the morning of demolition day after confirming the weather forecast. Never drain and then leave the shell empty for several days.

Where you’re allowed to discharge

You have three main options for where pool water goes:

1. Sewer discharge (preferred for most Newcastle and Lake Macquarie households) Pump to a sewer inspection opening (IO) or laundry cleanout, under a consent from Hunter Water. The most practical, legal and common method. See our pool water disposal cost guide for fees and consent detail. Requires a licensed plumber to make the connection if you are tapping into a cleanout inside the house.

2. Stormwater drain (with consent only) Only permitted in limited circumstances where water chemistry is within acceptable limits and a local council consent is in place. Not the default option and often not available.

3. Tanker cart-off A vacuum tanker pumps the pool and hauls the water to a licensed liquid-waste facility. Used when sewer discharge is not available or the water chemistry is too far outside acceptable limits to pre-treat practically. Adds to cost.

Pumping to the street gutter is not on this list. It is not a legal option.

Pump sizing and typical drain time

For a homeowner managing their own drain, a submersible pump is the standard tool:

A standard domestic submersible pump rented from a hire shop handles most residential pools. Put the pump at the deep end, run the discharge hose to the sewer IO, and let it run.

Near the end, the pump will cavitate as it struggles to pick up the last few centimetres of water. Move it to the lowest point and let it run until the suction sound changes, then switch off. A wet-dry vacuum can mop up the remaining sump water before the demolition crew arrives.

Coordinating with removal day

The best practice sequence for most residential concrete pools:

1. Stop adding chemicals 5-7 days before the planned drain.
2. Test water chemistry 2 days before drain. Adjust if needed.
3. Confirm final chemistry the morning of drain.
4. Pump to sewer IO under Hunter Water consent, starting early morning.
5. Complete drain and clean up hose run before end of business the day before demolition.
6. Contractor arrives the following morning with dry or near-dry shell.

For fibreglass pools on flat blocks with low groundwater risk, draining the day before is usually fine. On groundwater-affected sites, drain on the morning of demolition day.

Make sure pool plumbing and electrical decommissioning is done before you start pumping. The pool pump and electrical circuit must be isolated by a licensed electrician before the submersible pump is connected, to avoid live-circuit conflicts. Similarly, the salt chlorinator and pool equipment decommissioning step should be completed before draining so no equipment is damaged by dry operation.

When the contractor should drain, not you

There are circumstances where it is better to let the contractor handle the drain rather than doing it yourself:

• High groundwater sites: The contractor can monitor the shell during emptying and respond to any signs of movement.
• Fibreglass shells: The risk of floating is best managed by an experienced operator who can judge conditions on the day.
• Old or cracked shells: Draining a structurally compromised pool creates unpredictable crack propagation.
• Sewer connection required: A licensed plumber needs to make the connection to a sewer IO anyway, so the contractor coordinating this avoids you hiring a separate plumber.
• Uncertainty about water chemistry or consent: If you are not sure your water meets the discharge conditions, let the contractor assess it.

Ask at quote stage whether water disposal is included in the price, or whether it is priced as a separate item. Our full pool removal service includes water disposal planning as part of the scope.

For site-specific advice, request a free quote.

FAQs

Do I need a licensed plumber to drain my pool to the sewer?

You need a licensed plumber to make any new connection to the sewer line. If you are using an existing, accessible sewer IO that your pump hose can reach without a new fitting, the actual pumping does not require a plumber. But for any new connection inside the house (a laundry tap, cleanout, or fitting), use a licensed plumber. Confirm with Hunter Water what their current requirements are for residential pool drainage.

Can I use the pool’s own pump to drain it?

The pool’s built-in pump is designed to circulate water, not to evacuate the pool completely. It can reduce water level to a point, but cannot drain the last 200-400mm (sump depth). You will need a submersible pump for the final stage. Also, running the pool pump without adequate water can damage the pump impeller.

How long before removal day should I stop adding chemicals?

Typically 5-10 days, depending on current chlorine levels and weather. Sunny days and high temperature accelerate chlorine degradation. Test the water after 5 days; if it is within range, you are ready to drain. If not, give it another few days or add dechlorinator.

Can I drain a saltwater pool to my lawn?

Small amounts of very diluted saltwater can be tolerated by established turf, but the volume from a full pool is far too large. The salt concentration in an active salt pool (typically 4,000-6,000 mg/L) will kill or damage most lawn and garden plants if applied in bulk. Use a sewer discharge or tanker option.

What if it rains heavily just after I drain a fibreglass pool?

Contact your contractor immediately. Significant rainfall can rapidly raise groundwater around the shell. If demolition is not happening within hours, your contractor may advise partially re-filling the pool with mains water to prevent uplift. Do not leave an empty fibreglass shell unmonitored during or after heavy rain on a low-lying site.

Related reading

• Pool water disposal costs in NSW
• Pool plumbing and electrical decommissioning
• Salt chlorinator and pool equipment decommissioning
• What happens on pool demolition day
• Erosion and sediment control for pool removal sites
• Wet weather and pool removal delays
• Full pool removal service
• Fibreglass pool removal service