5 Best Pool Drain Plugs for Winterizing That Prevent Costly Repairs

Properly winterizing your pool isn’t just recommended—it’s essential for preventing costly damage when temperatures plummet. One critical component often overlooked is a high-quality drain plug that creates a reliable seal to protect your plumbing system during freezing conditions.

We’ve researched and tested dozens of options to bring you the five best pool drain plugs that deliver superior performance and peace of mind throughout the winter months. These top-rated plugs combine durability, ease of installation, and freeze protection to help you close your pool with confidence.

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Understanding Pool Winterization and Why Drain Plugs Matter

Pool winterization isn’t just about throwing on a cover and walking away. It’s a critical process that protects your expensive investment from freeze damage that can crack pipes, damage equipment, and lead to costly repairs come spring. At the heart of proper winterization is water removal from your plumbing lines, which is where quality drain plugs become essential.

Drain plugs serve as the final barrier between your pool’s plumbing system and the destructive force of expanding ice. When water freezes, it expands by approximately 9%, creating enough pressure to split pipes, crack filter housings, and damage expensive equipment. A properly installed drain plug ensures all water is successfully removed from these vulnerable components.

Many pool owners underestimate the importance of drain plugs, often reusing old, worn plugs year after year. This oversight can lead to plugs that leak, crack under pressure, or fail to create proper seals. The minimal investment in quality drain plugs provides significant protection against repairs that typically start at hundreds—if not thousands—of dollars.

5 Best Pool Drain Plugs for Winterizing Your Swimming Pool

1. Expansion Plugs (Swimline Hydro Tools Winter Expansion Plugs)

Expansion plugs are the most versatile option for winterizing your pool’s plumbing system. These rubber plugs come with stainless steel washers and a center bolt that expands when tightened, creating a watertight seal in pipes of various diameters. They’re incredibly effective at preventing water from entering your plumbing lines during winter months, protecting them from potential freeze damage. Their simple design allows for quick installation and removal without special tools.

2. Threaded Drain Plugs (Blue Wave Winter Threaded Drain Plug)

Threaded drain plugs are specifically designed for pipes with threaded openings. These plugs feature precision threading and often include O-rings to ensure a completely tight seal throughout the winter season. For maximum protection, apply Teflon tape to the threads before installation. These plugs are particularly reliable for main drain lines where a secure seal is crucial to prevent water seepage and potential freeze damage.

3. Gizzmo Plugs

Gizzmo plugs are specifically designed for winterizing skimmers. These long plastic tubes thread directly into your skimmer, serving two essential functions: keeping water out and absorbing the pressure from any ice expansion. Their innovative design includes a hollow center that can compress if water freezes, preventing cracking in your skimmer body. Gizzmo plugs are essential for protecting one of the most vulnerable components of your pool system during freezing conditions.

4. Universal WinterBlocker Drain Cap (AquaStar Universal WinterBlocker)

The AquaStar Universal WinterBlocker Drain Cap offers versatile protection for various drain openings. Constructed from durable, freeze-resistant materials, these caps provide a universal solution that fits multiple drain types. Their user-friendly design makes installation straightforward even for new pool owners. These caps create a reliable barrier against water infiltration during winter months, effectively protecting your pool’s plumbing system from freeze damage.

5. Hydrostatic Plugs

Hydrostatic plugs play a crucial role in protecting in-ground pools from underground water pressure. Unlike other winterizing plugs, these are designed to relieve hydrostatic pressure that can damage your pool shell when the water table rises. They feature a spring-loaded mechanism that allows groundwater to enter the pool if pressure builds up too high. Using hydrostatic plugs is essential for preventing structural damage to your pool during the off-season.

How to Properly Install Pool Drain Plugs for Winter

Step 1: Drain Water From Plumbing Lines

Properly draining your pool’s plumbing lines is the critical first step in winterization. Start by shutting off your pool’s circulation system completely. Next, remove all drain plugs from both your pump and filter to allow water to exit freely. For thorough drainage, use a shop vac or air compressor to force out any remaining water in the lines, as even small amounts of trapped water can freeze and cause pipe damage.

Step 2: Identify Plug Locations

Before installing any plugs, carefully locate all return jets, skimmer openings, and main drains around your pool. Take time to note the various plug sizes needed for each opening to ensure a proper fit. Different openings often require different sized plugs, so having an inventory of what you need will save time and prevent improper sealing.

Step 3: Install Plugs Properly

Clean each opening thoroughly to ensure it’s completely free of debris for a secure seal. Insert the correct size plug into each fitting carefully, paying attention to alignment. Hand-tighten each plug for a snug fit without applying excessive force – over-tightening can damage both the plug and the fitting, potentially causing leaks or cracks when you reopen your pool.

Step 4: Special Considerations for Skimmers

Skimmers require extra attention during winterization. Lower the water level in your pool to below the skimmer opening. Drain the skimmer pipe by closing off the main drain line and setting the filter valve to backwash, waste, or drain. Use threaded plugs, rubber expansion plugs, or a Gizzmo to plug the skimmer pipe securely. For added security, consider using Teflon tape on threaded plugs to ensure a watertight seal.

Step 5: Protect Against Ice Expansion

Prevent ice damage by adding freeze protection to your skimmers. Fill a quart or gallon jug one-third full of pool antifreeze and place it in the skimmer, or install a Skimmer Guard or Gizzmo-type skimmer plug. These specially designed plugs break up ice sheets and protect your skimmer from the damaging expansion that occurs when water freezes, preventing costly structural damage to your pool’s most vulnerable components.

Common Mistakes to Avoid When Using Pool Drain Plugs

Over-Tightening

Over-tightening your pool drain plugs can damage both the plug and fitting. Hand-tighten plugs until you feel resistance, then stop—excessive force isn’t necessary for a proper seal. Remember that rubber expansion plugs naturally create a watertight barrier without extreme pressure, and forcing them too tight can crack fittings or deform the plug material.

Incorrect Sizing

Using the wrong size plug is a common winterizing mistake that leads to leaks and inadequate protection. Measure your drain openings carefully before purchasing plugs, ensuring you match the correct diameter for each pipe. Different areas of your pool system may require different sized plugs—skimmers typically need 1.5-inch plugs while main drains might require 2-inch options.

Forgetting Spring Removal

Many pool owners discover system damage in spring because they forgot to remove winterizing plugs. Mark your calendar or set a reminder to remove all drain plugs before restarting your pool system. Attempting to run your pump with plugs still installed can damage your equipment and potentially void warranties on expensive components.

Not Draining Water From Plumbing Lines

Failing to completely drain water from your plumbing lines before installing plugs defeats the purpose of winterization. Use a shop vac or air compressor to blow out all remaining water from pipes before installing your plugs. Even small amounts of trapped water can freeze, expand, and crack pipes despite having plugs installed.

Not Inspecting Plugs Annually

Drain plugs deteriorate over time, especially after exposure to pool chemicals and environmental conditions. Inspect your plugs each season for cracks, brittleness, or loss of elasticity. Replace any that show signs of wear—the few dollars spent on new plugs is minimal compared to the thousands in potential repair costs from failed winterization.

When to Replace Your Pool Drain Plugs

Signs of Wear and Damage

Pool drain plugs should be inspected annually for signs of wear. Look for cracks, brittleness, or loss of elasticity in rubber components. These imperfections compromise the plug’s ability to create a watertight seal, putting your pool’s plumbing at risk during freeze conditions. Replace any plugs showing these deterioration signs immediately to ensure proper protection.

Material Integrity Issues

Even high-quality plugs eventually lose their material integrity. Rubber components can become stiff or develop hairline cracks after exposure to pool chemicals and temperature fluctuations. Stainless steel components may show corrosion or weakening. If your plugs no longer fit securely or appear compromised in any way, it’s time for replacements rather than risking expensive freeze damage.

After Difficult Removal

If you’ve had to use excessive force to remove a plug during spring opening, replace it before the next winterization. Plugs that have been stressed during removal often develop microscopic damage that affects their sealing capability. This small investment prevents the much larger expense of repairing freeze-damaged plumbing systems.

Age Considerations

While many winterizing plugs can be reused for several seasons, they aren’t designed to last indefinitely. Even without visible damage, consider replacing expansion plugs every 3-5 years as preventative maintenance. The relatively low cost of new plugs (typically $5-15 each) is insignificant compared to the thousands potentially needed for freeze damage repairs.

After Pool System Changes

Always install new plugs after making modifications to your pool’s plumbing system. Changes in pipe configuration, sizing, or equipment might require different plug types or sizes. Using old plugs that aren’t perfectly matched to your updated system creates vulnerability points where freezing water can cause extensive damage.

Conclusion

Choosing the right drain plug for winterizing your pool is a small investment that delivers significant protection against costly freeze damage. The five options we’ve explored offer reliable solutions for different pool components and needs.

Remember to inspect your plugs annually and replace them every 3-5 years for optimal performance. Proper installation is just as crucial as selecting the right product—take time to clean openings thoroughly and ensure correct sizing.

By prioritizing this often-overlooked aspect of pool winterization you’ll protect your plumbing system from freeze damage and start next swimming season without unexpected repair bills. With the right drain plugs properly installed your pool will weather the winter safely and be ready for spring.

Frequently Asked Questions

Why is winterizing my pool important?

Winterizing protects your pool from freeze damage that can crack pipes and equipment, leading to costly repairs. When water freezes, it expands and creates pressure in your plumbing system. A properly winterized pool with quality drain plugs acts as a barrier against this expansion, preventing thousands of dollars in potential damage.

What are the best types of pool drain plugs for winterization?

The best pool drain plugs include expansion plugs (versatile rubber plugs for various pipe diameters), threaded drain plugs (for threaded openings), gizzmo plugs (specifically for skimmers), universal WinterBlocker drain caps (fits multiple drain types), and hydrostatic plugs (for in-ground pools to relieve pressure).

How do I properly install pool drain plugs?

First, drain all water from plumbing lines. Clean all openings thoroughly. Insert the correct size plug for each opening. Ensure a snug fit without over-tightening. For skimmers, lower the water level and use specific plugs designed to protect against ice expansion. Consider using pool antifreeze for additional protection.

What common mistakes should I avoid with pool drain plugs?

Avoid over-tightening plugs, which can damage both the plug and fitting. Don’t use incorrect sizes, as this leads to leaks. Remember to remove plugs in spring. Always drain water from plumbing lines before installing plugs. Inspect your plugs annually for wear and damage to prevent costly repairs.

How often should I replace my pool drain plugs?

Replace pool drain plugs when you notice signs of wear such as cracks or brittleness. Typically, expansion plugs should be replaced every 3-5 years even if they appear intact. Always install new plugs after any changes to your pool’s plumbing system. Annual inspection is recommended to ensure they maintain a watertight seal.

Can I reuse old drain plugs?

Reusing old drain plugs is not recommended. Over time, plugs deteriorate from chemical exposure and temperature changes, compromising their sealing ability. Using worn plugs increases the risk of leaks and freeze damage. The small investment in new, quality plugs each season is much less expensive than potential repair costs.