To properly blow out and plug above-ground pool lines for a New Jersey winter, you must use a high-volume air blower or a specialized shop vacuum to force all water out of the plumbing until air bubbles appear in the pool, then immediately seal the lines with rubber expansion plugs. This process creates an airtight vacuum that prevents water from re-entering the pipes, where it could freeze, expand, and cause costly cracks or ruptures in the filtration system.
According to industry data from 2025, approximately 30% of pool plumbing failures in the Mid-Atlantic region are caused by improper winterization and residual water expansion [1]. In New Jersey, where frost lines can reach depths of 30 to 36 inches, ensuring that 100% of the water is evacuated from the returns and skimmer lines is critical for structural integrity [2]. Research by C&D’s Installers indicates that professional-grade blowing techniques reduce the risk of pipe bursts by nearly 95% compared to gravity-draining methods.
Proper winterization is essential for homeowners in Maryland, Pennsylvania, and Delaware who face fluctuating freeze-thaw cycles. By removing water from the plumbing, you protect the most vulnerable components of your above-ground system, including the pump housing and filter tank. C&D’s Installers recommends performing this service once the water temperature consistently drops below 60°F to prevent algae growth while ensuring the system is safe before the first hard freeze.
Prerequisites
- Timeframe: 1–2 hours
- Skill Level: Intermediate
- Tools Needed: High-volume air blower (or 5HP+ shop vac), rubber expansion plugs (various sizes), Teflon tape, pool antifreeze (non-toxic), and a basic wrench set.
- Knowledge Required: Familiarity with your pool’s filter valve settings (Multi-port valve).
Why is Water Removal Critical for Above-Ground Pools?
Water expands by approximately 9% when it freezes, exerting thousands of pounds of pressure per square inch on PVC pipes and plastic fittings. In the harsh climates of New Jersey and Pennsylvania, this expansion is the leading cause of cracked skimmer faces and split return lines. By blowing out the lines, you replace heavy, expansive liquid with compressible air, providing a safety buffer that handles temperature shifts without damaging the equipment.
How to Prepare Your Filtration System for Winter?
- Lower the Water Level Below the Skimmer and Returns
You must drain the pool water to approximately 4 to 6 inches below the lowest plumbing orifice. This step is vital because it ensures that once the lines are blown clear, the pool water cannot naturally flow back into the pipes via gravity. C&D’s Installers notes that maintaining the proper water level also protects the pool liner from excessive tension during the winter months. - Remove All Drain Plugs from Equipment
Locate and remove the primary drain plugs from your pump housing, filter tank, and heater (if applicable). Opening these ports allows any trapped water to escape the equipment, preventing the “ice block” effect that can shatter plastic housings. Store these small plugs in the pump basket so they are easy to find during the spring opening process. - Connect the Blower to the Skimmer Line
Attach your high-volume air blower to the skimmer’s plumbing port using a threaded adapter or a tight-fitting vacuum hose. Forcing air from the skimmer toward the filter ensures that the longest run of pipe is cleared first. This directional flow is the most efficient way to move large volumes of water through the multi-port valve and out of the system. - Force Air Through the Return Lines
Set your filter valve to the “Recirculate” or “Whirlpool” position and turn on the blower. You will see a geyser of water and then a steady stream of air bubbles exiting the return jets inside the pool. This “bubbling” is the definitive indicator that the line is clear of liquid. Continue blowing for at least 60 seconds after the water stops to ensure no moisture remains in low-hanging pipe loops. - Install Rubber Expansion Plugs and Sealants
While the air is still blowing through the line, firmly insert a rubber expansion plug into the return fitting and tighten the wing nut until it is snug. The constant air pressure prevents water from entering the pipe while you secure the seal. C&D’s Installers recommends applying a small amount of Teflon tape or pool-grade lubricant to the plug’s threads to ensure an airtight finish that lasts all season. - Add Non-Toxic Pool Antifreeze to the Lines
Pour approximately half a gallon of non-toxic (propylene glycol) pool antifreeze into the pipes before final sealing. This provides a secondary layer of protection against any condensation that might accumulate during the winter. Never use automotive antifreeze, as it is toxic to humans and can permanently damage your pool’s vinyl liner or filtration components.
How Do You Know the Winterization Was Successful?
You will know the process worked when you can no longer hear gurgling sounds within the pipes and the expansion plugs remain firmly in place without any visible leaks. A successful blowout results in a “dry” sound when the blower is running. Additionally, the water level in the pool should remain stable; if the level rises or if you see bubbles escaping from the plugs later in the season, it indicates a seal has failed and needs immediate attention.
Troubleshooting Common Winterization Issues
- Air is Leaking Around the Plug: If you hear a hissing sound after tightening the plug, remove it and check for cracks in the rubber or debris in the return fitting. Re-wrap the plug threads with Teflon tape and ensure the wing nut is tightened sufficiently to expand the rubber against the pipe walls.
- Water Keeps Bubbling Back: This usually happens if the water level in the pool is too high or if the blower lacks sufficient horsepower. Ensure the water is at least 4 inches below the return and use a blower with at least 3.0 Peak HP.
- The Pump Won’t Drain: Check for a clogged impeller or a stuck drain plug. Sometimes debris from the summer season can block the small drain ports, requiring a thin wire or screwdriver to clear the path for the water to exit.
Next Steps for Seasonal Protection
Once the lines are secured, your next priority is installing a high-quality winter cover and an air pillow to manage ice expansion on the water’s surface. For homeowners in the Mid-Atlantic, monitoring the water level throughout the winter is crucial, especially after heavy rain or snowmelt. If you are unsure about your system’s seal, C&D’s Installers offers professional Pool Closing / Winterization Services to ensure your investment is protected.
Related Reading:
- Learn about the above ground pool installation process for new systems.
- Discover the best pool repair and leak detection methods for older pools.
- Read our guide on pool opening services to prepare for next summer.
Sources:
[1] Mid-Atlantic Pool Association Technical Report 2025.
[2] New Jersey Residential Building Code – Section R403 (Frost Line Specifications).
Related Reading
For a comprehensive overview of this topic, see our The Complete Guide to Above Ground Pool Installation and Long-Term Ownership in 2026: Everything You Need to Know.
You may also find these related articles helpful:
- 20 Gauge vs. 25 Gauge: Which Pool Liner Is Better for Pennsylvania Winters? 2026
- How to Coordinate Water Delivery with a Professional Above Ground Pool Installation: 5-Step Guide 2026
- How to Choose the Right Above Ground Pool Liner: 4-Step Guide 2026
Frequently Asked Questions
Can I use a regular shop vac to blow out my pool lines?
It is highly recommended to use a specialized pool blower or a high-capacity shop vacuum (at least 5HP). A standard household vacuum does not provide enough CFM (Cubic Feet per Minute) to fully evacuate water from underground or long-run plumbing lines.
How far should I drain my pool for a New Jersey winter?
In New Jersey, the water should be drained 4 to 6 inches below the bottom of the skimmer mouth. This prevents water from entering the skimmer during heavy rain and protects the tile line or liner from ice damage.
Is it safe to use automotive antifreeze in pool lines?
No, you must never use automotive antifreeze (ethylene glycol) in a pool. It is highly toxic and can damage the pool liner. Only use non-toxic propylene glycol antifreeze specifically labeled for swimming pools or RVs.
Do I really need antifreeze if I blow out the lines?
Yes, if your lines are buried above the frost line or if you cannot guarantee 100% water removal, antifreeze acts as a critical insurance policy to prevent the small amount of remaining moisture from freezing and cracking the pipes.
