7 Best Pool Drain Plugs for Winterizing That Seal Tight

As the first frost approaches, the annual ritual of closing the pool becomes a top priority for protecting plumbing from costly freeze damage. Choosing the right drain plug ensures that your pipes remain dry and secure throughout the coldest months of the year. This guide breaks down the most reliable options available to help you safeguard your investment with confidence.

Hayward SP1022C Plug: A Tried-and-True Classic

When dealing with standard return lines, the Hayward SP1022C serves as the industry baseline for reliable sealing. Its threaded design fits most standard wall returns, making it a go-to choice for homeowners who prefer simplicity and a straightforward installation process.

Because it relies on a threaded connection, ensure that the threads on your pool wall fitting are free of debris and scale before installation. A clean interface prevents cross-threading and ensures the gasket creates a watertight seal. This is an affordable, no-nonsense solution for the budget-conscious homeowner.

Bottom line: If your plumbing is standard and well-maintained, this plug provides the most reliable seal for the lowest price point.

The “Gizzmo” Skimmer Plug: Ultimate Ice Protection

The Gizzmo is specifically engineered to handle the expansion of freezing water inside your skimmer housing. Unlike standard rubber plugs, this device features a hollow, compressible body that absorbs the pressure of ice buildup, preventing the skimmer from cracking.

For those living in climates with frequent freeze-thaw cycles, this is an essential piece of insurance. It is highly recommended to use the standard Gizzmo for most applications, though professional-grade versions are available for deeper skimmers. Installation requires care to ensure the threads seat properly without catching.

Bottom line: The Gizzmo is a non-negotiable investment for homeowners in colder climates where skimmer cracks are a common winter nightmare.

Pentair Rainbow #9 Plug: For a Perfect Skimmer Seal

The Pentair Rainbow #9 is a heavy-duty option often favored for its robust construction and superior gasket quality. It is designed to fit snugly into skimmer ports where a high-tension seal is required to keep water out of the line completely.

This plug is particularly useful if the threads in your skimmer have become slightly worn or damaged over time. The substantial rubber expansion ring provides enough grip to hold firm, even when thread integrity is questionable. It offers a higher level of peace of mind than basic plastic threaded plugs.

Bottom line: Choose the Rainbow #9 if you need a plug that compensates for minor wear and tear in your existing pool components.

Oatey 33402 Rubber Plug: The Most Versatile Option

Originally designed for plumbing maintenance, the Oatey 33402 has become a secret weapon for pool owners. Its wing-nut expansion design allows it to be used in almost any pipe diameter, provided the size is within the plug’s specified range.

This versatility makes it the perfect “just in case” item to keep in the garage. Whether a specific return line has an irregular size or you have lost track of the original plug type, this rubber expansion plug will likely get the job done. Simply insert and tighten the wing nut until the rubber expands to fill the opening.

Bottom line: Keep a few of these in your winterization kit for emergencies, as they handle non-standard pipe sizes better than any other option.

B&S Products T-Handle Plug: Easiest to Tighten

Tightening winter plugs can be a challenge when working in cold water or awkward, hard-to-reach positions. The B&S Products T-handle plug solves this by providing extra leverage, allowing you to get a firm seal without needing a wrench or pliers.

The T-handle design is particularly beneficial for those with limited grip strength or for homeowners who find kneeling by the pool deck uncomfortable. The sturdy handle stays accessible, making the removal process in the spring just as easy as the installation in the fall. It is a user-friendly upgrade that prioritizes ergonomics.

Bottom line: This is the premier choice for homeowners who want to avoid fumbling with small, slippery wing nuts in freezing temperatures.

Anderson #8 Rubber Plug: A Simple, Dependable Fix

Anderson plugs are widely respected for their high-quality rubber compounds that resist drying out and cracking over several seasons. The #8 size is a standard for many smaller return lines and provides a reliable, low-profile seal.

Because these plugs sit flush against the wall fitting, they are less likely to be bumped or damaged during the winter months. They are simple to install, durable, and offer a professional finish that satisfies the needs of most residential pools. They represent the middle ground between basic affordability and premium durability.

Bottom line: If you prefer a “set it and forget it” solution, the Anderson #8 is the most dependable choice for consistent performance year after year.

Aladdin Winter Duck Plug: For In-Ground Return Lines

The Aladdin Winter Duck Plug is a specialized tool designed to plug return lines effectively without the need for manual tightening. Its internal mechanism uses water pressure or a simple push-and-turn action to set the seal, which is ideal for deep pipes.

These plugs are particularly favored by those who maintain multiple pools or have complex plumbing configurations. They minimize the time spent kneeling on the deck, which is a major advantage during late-season maintenance. While they come at a slightly higher price, the convenience they offer is significant.

Bottom line: Opt for the Duck Plug if you value time-saving technology and want to minimize physical exertion during the winterization process.

How to Measure Your Pool Lines for a Perfect Fit

Measurement is the most critical step in preventing leaks during the winter. Using a standard measuring tape or calipers, measure the inside diameter (ID) of the pipe or fitting where the plug will be inserted. Do not guess based on the pipe’s exterior size, as wall thickness varies significantly.

• For threaded fittings: Measure the diameter of the opening.
• For smooth-walled pipes: Measure the actual inside diameter to ensure the rubber expansion range of your chosen plug covers it.
• Keep a record: Store the specific sizes required for your pool’s skimmer, returns, and main drain in your utility binder to simplify future shopping.

Bottom line: Always measure twice; buying the wrong size plug is the leading cause of winterization failures.

Rubber Expansion vs. Threaded Plugs: Which to Use

Threaded plugs are best when the pool wall has a clean, intact threaded fitting. They are generally less expensive and provide a permanent, positive lock that is difficult to dislodge accidentally. However, they do not accommodate any variance in pipe size.

Expansion plugs are more forgiving and can seal non-threaded pipes or fittings with damaged threads. They work by compressing a rubber ring against the pipe walls, creating a friction seal. These are essential for older pools where threads may be corroded or stripped.

• Choose Threaded: If you have newer equipment or plastic fittings in excellent condition.
• Choose Expansion: If your pipes are older, damaged, or lack internal threads.

Bottom line: If in doubt, an expansion plug is the safer, more universal bet for varying pool conditions.

A Quick Checklist for Installing Your Winter Plugs

Proper installation involves more than just inserting the plug; it requires attention to detail to ensure a watertight environment. Follow this checklist to ensure your plumbing stays safe all winter long.

• Clear the debris: Remove all scale, sand, or leaves from the pipe opening to ensure the plug makes contact with the actual pipe material.
• Check the gaskets: Ensure the O-rings on your plugs are not cracked, brittle, or missing.
• Tighten carefully: If using expansion plugs, tighten only until you feel firm resistance; over-tightening can crack older PVC fittings.
• Verify the seal: Once installed, check for any slow drips; if a drip persists, remove the plug, clean the area again, and re-seat it.

Bottom line: A slow drip in the fall turns into a major crack in the spring, so verify every plug before walking away.

Investing in high-quality drain plugs is a small but vital step in protecting your pool from the harsh realities of winter. By choosing the right design for your specific plumbing setup, you ensure that spring opening is a breeze rather than a repair project. Take the time to measure correctly and prepare your lines properly to enjoy a stress-free transition into the warmer seasons.