7 Best Winterizing Plugs for Closing Pools That Hold

Preparing a pool for the long winter months remains one of the most critical maintenance tasks for any homeowner. A failure in the plumbing or skimmer seals can lead to costly structural damage or frozen pipes once temperatures drop. Selecting the right winterizing plug ensures that peace of mind is maintained throughout the coldest season of the year.

Hayward SP1022C: The Go-To for Hayward Skimmers

When the pool equipment utilizes Hayward skimmer assemblies, the SP1022C is the standard for a reason. This plug is designed specifically to fit the precise threading of Hayward’s common return and skimmer ports. Because it is a direct manufacturer match, there is no guessing about whether the threads will catch or if the seal will hold under pressure.

These plugs feature a durable construction that withstands the expansion and contraction associated with freezing water. For households that prefer sticking to brand-specific components, this is the most reliable choice. It simplifies the winterization process by eliminating the need for makeshift rubber stoppers that might degrade over time.

• Best for: Owners of standard Hayward skimmer systems.
• Bottom line: Rely on manufacturer-specific parts when compatibility is the primary concern.

Anderson #9: The Classic Tapered Rubber Stopper

For older pools or those where threading has become worn or damaged, the Anderson #9 tapered plug acts as a universal problem solver. This plug functions by wedging itself into the pipe opening, creating a friction-based seal. It is an ideal solution for those who struggle with identifying the exact thread size of their intake ports.

The rubber compound used in these stoppers is specifically formulated to remain pliable even in near-freezing temperatures. However, because it relies on friction, the hole must be clean and free of debris for the seal to set properly. This is an affordable, low-tech option that has served homeowners well for decades.

• Best for: Older plumbing systems or pipes with stripped threads.
• Bottom line: An inexpensive, versatile staple that belongs in every pool owner’s winter toolkit.

Winter Duck Plug: Blow Out Your Lines with Ease

Winterizing requires blowing air through the lines to remove residual water, and the Winter Duck plug makes this a one-person job. These plugs typically feature a hollow center with a valve that allows for the attachment of an air compressor hose. Once the line is clear, the valve is closed to seal the pipe off completely.

This design is a significant time-saver for those who handle pool closing chores without professional assistance. It eliminates the need to constantly swap between a blower attachment and a sealing plug. By keeping the system closed while working, you prevent water from back-flowing into the pipes during the process.

• Best for: DIYers who want a streamlined, efficient winterization routine.
• Bottom line: Investing in a multi-functional plug pays for itself in labor hours saved.

The Gizzmo: Best Skimmer Ice Damage Protector

The Gizzmo is essentially an insurance policy for the pool skimmer housing. Unlike standard plugs that merely stop water flow, a Gizzmo is designed to collapse inward if ice forms inside the skimmer, absorbing the pressure that would otherwise crack the plastic housing. It is a dual-purpose tool that plugs the line and protects the structural integrity of the equipment.

For homeowners in climates where hard freezes are a recurring reality, this is an essential upgrade. It replaces the need for floating jugs or other DIY hacks meant to displace ice expansion. While it is slightly pricier than a basic rubber plug, the cost of replacing a cracked skimmer assembly far outweighs the initial investment.

• Best for: Regions with heavy snowfall and prolonged freezing temperatures.
• Bottom line: Never overlook skimmer protection; the Gizzmo is the gold standard for avoiding expensive spring repairs.

Wing Nut Plug: For a Rock-Solid, High-Pressure Seal

When dealing with deep-seated pipes or high-pressure return lines, a wing nut plug offers superior security. These feature a metal or heavy-duty plastic plate compressed by a bolt and wing nut, which expands a thick rubber gasket against the pipe walls. The mechanical advantage provided by the wing nut ensures a much tighter fit than a standard friction plug.

This design is perfect for homeowners who worry about their plugs slipping or being forced out by ice expansion. It provides a tactile confirmation that the seal is tight, as you can physically feel the resistance when tightening the wing nut. They require a bit more effort to install but provide unmatched peace of mind for stubborn, high-pressure pipes.

• Best for: High-pressure lines and situations where a “set-it-and-forget-it” seal is required.
• Bottom line: If you prefer to over-engineer your safety measures, the wing nut plug is the ideal candidate.

Pentair Quick-Twist: Easiest for Pentair Systems

Pentair owners often find the Quick-Twist system to be the most convenient way to secure their returns. These plugs are engineered to lock into place with a simple quarter-turn, mimicking the ease of a bayonet-style connection. This saves the user from the tedious task of screwing in a standard plug through several rotations.

The ease of use is particularly helpful for those with limited mobility or back issues who find leaning over the pool deck challenging. Because they are designed specifically for the Pentair footprint, they offer a professional-grade fit without the struggle of manual tightening. They are a premium convenience item that effectively bridges the gap between reliability and speed.

• Best for: Pentair system owners who prioritize ease of installation.
• Bottom line: Simplify the maintenance checklist by choosing components designed specifically for your system’s quick-connect hardware.

Threaded Plug w/ O-Ring: For Standard Returns

For many standard pool returns, a simple threaded plug equipped with a rubber O-ring provides the best balance of price and performance. The O-ring acts as a secondary gasket, ensuring that even if the threading is slightly imperfect, water cannot seep past the seal. It is a straightforward, no-nonsense solution that works with the majority of modern pool wall fittings.

These are incredibly easy to store in the off-season, as they are compact and do not require specialized tools for removal. Keeping a few spares in the pool supply cabinet is a wise move, as these can occasionally be misplaced or stripped if overtightened year after year. They represent the most common, cost-effective choice for general pool closing.

• Best for: Everyday, standard pool returns where simplicity is key.
• Bottom line: Keep a small supply on hand; they are the reliable backbone of pool winterization.

Finding Your Fit: How to Measure for the Right Plug

Before purchasing, you must identify the exact diameter of the pipe opening. A standard ruler or caliper works well; simply measure the inside diameter (ID) of the threaded or smooth pipe. Never rely on an eyeball estimate, as a plug that is even a fraction of an inch too small will fail under the weight of winter ice.

If the pipe has threads, ensure the plug also has threads that match the pitch of the existing fitting. For smooth pipes, the goal is to choose a plug with an expansion range that centers on your measured diameter. Always opt for a size that allows the rubber to expand comfortably, rather than forcing the plug to its maximum expansion limit.

• Measure twice to ensure a perfect, airtight seal.
• Check for debris inside the pipe threads before measuring.

Tapered vs. Threaded Plugs: Which Do You Need?

Threaded plugs are superior for systems where the plumbing already has matching internal threads. They offer a mechanical lock that is difficult to dislodge, making them the preferred choice for permanent fixtures. If the pipe is threaded, always choose a threaded plug over a tapered rubber alternative to ensure longevity.

Tapered plugs, conversely, are the “universal” option for pipes lacking threads or for older systems with damaged openings. While they are highly effective, they rely entirely on the rubber’s grip against the pipe wall. They are the better choice for non-standard pipes but require a clean, dry surface to prevent slippage.

• Use threaded for stability; use tapered for versatility.
• Always verify if your return lines have internal threads before ordering.

Getting a Leak-Proof Seal Without Over-Tightening

The most common mistake during pool closing is over-tightening plugs in an attempt to prevent leaks. Excess force can crack the plastic fitting, create a stress point for future leaks, or damage the rubber gasket of the plug itself. A snug, firm fit is all that is required for a watertight seal.

When installing, ensure the threads are clean and the rubber gasket is lubricated with a light coating of pool-safe silicone grease if necessary. If a plug resists turning, stop immediately, back it out, and ensure the threads are aligned correctly. Respecting the materials ensures that both the plug and the pool pipe remain in good condition for the following season.

• Hand-tighten only; avoid using tools that provide excessive torque.
• Check for a tight, consistent seal by observing for drips for a few minutes after installation.

Proper winterization remains the most effective way to protect a backyard investment from the harsh realities of seasonal weather. By matching the right plug to the specific needs of your pool’s plumbing, you ensure that the system remains safe, secure, and ready for use when the warmer months return.