If you’re a pool owner preparing for the off-season, one of the most critical steps in winterizing your pool is draining it to the appropriate level before covering it with a safety cover. But how far to drain a pool with a safety cover can be confusing, especially if you’re new to pool maintenance or if your pool system is unique.
This guide will walk you through everything you need to know, including the variables that influence how low you should drain your pool, the best practices to protect your pool structure and cover, and what mistakes to avoid. Whether you own an above-ground or in-ground pool, this detailed resource will provide you with the insights you need to confidently protect your investment during the cold months.
Why Draining Your Pool Correctly Matters
Before diving into the “how far” aspect, it’s important to understand the “why.” Properly draining your pool before winter is crucial for several reasons:
- To Prevent Freeze Damage: In regions where temperatures drop below freezing, water expands as it freezes. If your pool is overfilled, freezing can crack tiles, skimmers, and even the pool walls or shell.
- To Protect Pool Equipment: Water in the lines, filters, or heaters can likewise freeze and cause costly damage if not properly drained and winterized.
- To Avoid Ice Load Stress: Once you apply a safety cover, snow and ice will accumulate over winter. Adequately lowering the waterline provides a buffer that absorbs this weight without stressing the cover or the pool structure.
The safety cover is an essential line of defense in winter pool maintenance, but it works most effectively when the pool is prepared correctly—including draining the water to the right level.
How Far Should You Drain Your Pool with a Safety Cover?
The most commonly recommended answer is: drain the water to 12 to 18 inches below the skimmer, or roughly at the level of the tile line base or the second step of the pool. However, this can vary depending on several factors.
Let’s take an in-depth look at this recommendation and the variables that affect it.
Understanding Your Pool Type
In-Ground Pools
For in-ground pools with a safety cover, the rule of thumb applies—12 to 18 inches below the skimmer. This ensures the water isn’t so low that it stresses the pool floor (especially vinyl liners), but still low enough to accommodate ice expansion and snow weight.
If you have a concrete (gunite or shotcrete) pool, the structure can handle greater pressure, but it’s still important to follow this guideline. Fiberglass pools are slightly more susceptible to hydrostatic pressure and should always have a hydrostatic relief valve in the main drain to prevent lifting or cracking.
Above-Ground Pools
These pools typically have less structural complexity but are still vulnerable to winter weather. Many manufacturers recommend draining to just below the skimmer level but not completely empty. Some even suggest leaving the water level just above the floor of the pool. Draining too low can disrupt wall alignment or collapse the structure, especially with high snow or wind pressure on the cover.
Always check the manufacturer’s specifications for your specific above-ground pool model. In many cases, the ideal level is:
- 8 to 12 inches below the skimmer for above-ground pools with a rigid or rigid-top structure.
- Higher levels (closer to 6 inches below skimmer) if you live in a climate that sees minimal snowfall or freezing temperatures.
Climate and Weather Considerations
The climate in your region is one of the biggest determinants of how far you should drain your pool. Here’s how:
| Climate Type | Recommended Draining Level | Reasoning |
|---|---|---|
| Harsh Winter Climates (Freezing Temperatures Below 32°F / 0°C) | 12–18 inches below skimmer | Mitigates against ice expansion and snow weight pressure on safety cover. |
| Moderate Winter Climates (Occasional Freezes, Low Snowfall) | 6–12 inches below skimmer | Reduced risk of freeze damage while keeping vinyl liners or pool surfaces wet. |
| Warm Winter Climates (Fewer than 3 Freezing Days per Year) | Minimal to No Draining Needed | Covers act as debris barriers rather than freeze protection; water can remain near normal. |
This table underscores the fact that pool regions with little to no freezing may not require significant draining. The goal is always safety and structural integrity first.
Skimmer and Tile Line Positioning
The skimmer is a critical component in your pool’s circulation system. When a pool is closed, the water should be low enough not to freeze inside it. Hence, it’s generally recommended to drain the water level well below the skimmer opening. Here’s a quick guideline:
- If your skimmer sits flush with the waterline, drain to 12 to 18 inches below it.
- If your pool has a skimmer with a secondary weir (like many modern pools), you can sometimes lower it slightly more than 18 inches but should not excessively drop below that range.
The tile line also offers a visual guide. Typically, the water is lowered just to the base of the tile. This helps prevent ice damage while keeping the tile area from drying out and potentially cracking or deteriorating.
Material and Construction of the Pool
Not all pools respond the same to water level changes, especially over winter.
Vinyl Liner Pools
These pools are particularly sensitive to low water levels. Draining too low can cause the liner to shrink, wrinkle, or tear when temperatures warm up and the liner expands.
- Ideally, keep water levels around 6 inches above the bottom of the deep end floor.
- Some use floating winter plugs or safety cover support systems to minimize wrinkles and maintain liner tension.
Concrete, Gunite, and Fiberglass Pools
While these constructions are sturdier, they still need the water level lowered appropriately to avoid damage. Again, 18 inches below the skimmer is a safe standard.
- Concrete pools can withstand more pressure but may experience surface cracks without proper winterization.
- Fiberglass pools are flexible but can suffer from bowing, cracking, or shifting under excessive freeze or hydrostatic pressure.
Factors Beyond Water Level: Cover Compatibility and Winter Weight Load
Draining your pool isn’t the only consideration. Your safety cover and how it will endure the winter play a direct role in determining the ideal draining depth.
Water Level and Winter Cover Fit
A properly fitted safety cover should lie flat, with the water level adjusted so that it does not sag or create a dome. Too little water can cause the cover to dip below the pool deck, trapping debris and snow. Too much water, and the cover might not stretch over adequately or cause ice damage.
- If your safety cover has a support system (like air pillows or water bags), the drained water level can be slightly higher (closer to 12 inches below the skimmer) since these systems raise the cover to accommodate ice and snow.
- For solid safety covers (which cover the entire surface), a lower water level is preferred to avoid hydrostatic pressure and prevent the cover from lifting or bulging.
Hydrostatic Relief and Its Importance
One often-overlooked aspect of draining pool water is hydrostatic pressure from groundwater. In regions with high water tables, groundwater can rise and push up against the pool floor, especially when the pool is drained too low or completely emptied.
To counter this:
- Ensure your in-ground pool has a working hydrostatic relief valve in the main drain.
- Do not drain the pool more than necessary, especially in areas with heavy rainfall or high subsoil water levels.
Tools and Techniques to Achieve the Correct Draining Level
If you’re unsure how far to drain, especially visually, several techniques and tools can help:
Using a Pool Valve
Most pools have a valve at the base of the pump system or a dedicated drain located in the deep end. Using this valve allows gravity to do most of the work, reducing the need for a pump.
- Attach a hose to the external drain and lead it away from your pool area.
- Monitor the drop for reference marks on the pool wall or a level tape measure.
Pool Winterization Instruments
These specialized tools can help pool owners gauge when to stop draining:
- Water level indicators: Stick-on or floating devices that provide a quick read for optimal drainage level.
- PVC markers: Custom-made PVC poles marked in inches can be placed inside the pool to indicate proper levels.
Using Steps and Skimmer as Guides
If your pool has a standard design with a second or third step, these can be excellent reference points. Typically, the second step is about 12 to 18 inches below the skimmer—right where you want your final water level after draining.
Draining Mistakes You Should Avoid
Understanding what not to do prevents long-term damage and costly repairs. Here are some common mistakes pool owners make when draining:
Draining Too High
- What happens? Water still reaches into the skimmer and can freeze, damaging components.
- Best practice: Drain at least 12 inches below the skimmer and ensure water bags or pillows are installed properly if you’re using a safety cover with support.
Draining Too Low
- What happens? Liners can shrink, the structure can hydrostatically lift, and vinyl can tear.
- Best practice: Reference the pool manufacturer’s instructions, and ensure the lowest point is above structural joints and below water-sensitive equipment.
Forgetting Climate and Geographical Hazards
- What happens? A pool drained too high in a cold region can crack or shift under pressure; one drained too low in a rainy area can float out of place.
- Best practice: Always research local weather patterns and groundwater conditions before closing your pool for the season.
Step-by-Step Draining and Covering Instructions
Here’s a simple, structured way to ensure you drain your pool and apply the safety cover correctly:
- Balance the pool water chemistry: Test and adjust the pH, alkalinity, and chlorine levels.
- Apply winter algaecide and shock treatment: Prevent dormant algae growth and protect the water quality until opening next season.
- Backwash and clean your filter system: Clean or replace cartridges, then run a cleaning cycle.
- Drain pool water to the recommended level (12–18 inches below skimmer).
- Plumb out all water lines and install antifreeze where needed: Blowing out lines and using winter plugs is crucial to prevent freeze damage.
- Install safety cover supports: Use air pillows or water tubes to lift and support the cover, accommodating ice expansion.
- Secure the safety cover: Use winch kits, straps, and anchors to hold the cover firmly across the edges and deck.
Double-check that your drain valves are closed, and set covers snugly with proper tension to endure wind and snow load.
Final Notes: Expert Tips from Pool Professionals
If you’re still uncertain about how far to drain your pool with a safety cover after reviewing your pool’s manual or this guide, here are some expert insights:
- When in doubt, drain less than more: It’s easier to pump out a few more inches later than to rectify damage from an over-drained pool.
- Monitor environmental conditions pre-closure: Heavy rainfall or an unexpected early freeze can affect your draining strategy.
- Record your adjustments: Keeping notes every season helps improve your process and adjust based on performance.
- Consider annual pool winterization services: If you’re pressed for time or unsure about the process, hiring a licensed pool service expert can ensure safe and effective closure.
Conclusion: The Right Drainage Makes All the Difference for Your Pool
In summary, knowing how far to drain a pool with a safety cover is a nuanced decision that requires understanding your pool’s type, structure, location, and local climate. The general guideline—12 to 18 inches below the skimmer—provides a solid starting point for in-ground pools, but specific conditions may require minor adjustments. Above-ground pools, in particular, have unique needs that must be honored to avoid structural compromise.
Proper pool draining sets the stage for an effective safety cover and a damage-free winter. Whether this is your first time or you are a seasoned pool owner looking for a refresher, approaching your winterizing process with thoroughness and care ensures your pool remains in excellent condition and is easy to open next season.
Taking the time to learn and follow best practices today could save you thousands in repairs tomorrow—and ensure your backyard oasis is ready when summer returns.
How far should I drain my pool before installing a safety cover?
Draining a pool before installing a safety cover is essential to protect the pool and cover during the off-season. For most in-ground pools, it’s recommended to drain the water to about 12 to 18 inches below the skimmer. This level prevents water from freezing and causing damage to the skimmer and return jets. However, the exact level may vary depending on your pool’s design and the type of safety cover you’re using, so it’s best to consult the manufacturer’s guidelines.
Above-ground pools typically require different handling, as they lack the same plumbing setup as in-ground pools. Generally, it’s best to lower the water level to just below the skimmer opening or return lines. This helps reduce pressure on the pool walls during winter and makes cover installation more secure. As always, ensure you check both the cover and pool manuals for specific recommendations to avoid structural or cover-related damage.
Why can’t I completely drain my pool when using a safety cover?
Completely draining your pool might seem like a practical option for maintenance or winterization, but it can actually be harmful, especially for in-ground pools. Without the proper water level, the hydrostatic pressure from groundwater can push the pool structure up, causing cracks, shifting, or even complete lifting from the ground. The remaining water serves as a counterbalance against these forces and ensures structural integrity.
Structural damage due to over-draining can be expensive and time-consuming to fix, far outweighing any perceived benefit from complete drainage. In addition to underground water pressure concerns, empty pools lose the stability provided by water in the main drain and may warp under various weather conditions. Safety covers are designed to work with a specific water level to maintain their effectiveness and protect your pool properly.
How do I determine the right water level for a safety cover on my specific pool type?
The right water level depends primarily on your pool’s construction type—whether it is in-ground or above-ground—and its specific plumbing setup. In-ground pools with a skimmer system should typically have the water level lowered to about 12 to 18 inches below the skimmer mouth. This allows room for winter water movement while preventing freeze damage. Pools without a skimmer (such as some newer designs) might require a different approach.
A professional pool service or your pool’s manufacturer can help identify precise levels based on your unique setup. For above-ground pools, water levels are usually lowered just below the skimmer or return fitting to relieve stress on the pool wall seams. By following these guidelines, you protect both the structure and equipment while allowing the safety cover to function properly.
What happens if I leave the water level too high when covering my pool?
Leaving the water level too high before installing a safety cover can lead to serious issues, especially during freezing weather. Water expands when it freezes, which can cause damage to skimmers, return jets, and plumbing lines if there isn’t enough room to accommodate expansion. Additionally, ice buildup in an improperly drained pool may distort the cover, create water pockets, or tear the fabric, reducing its effectiveness and lifespan.
In some cases, excess water can overflow and damage the surrounding decking, landscaping, or equipment. Furthermore, the extra water pressure on a safety cover can strain its anchor system, which might lead to shifting or lifting during wind or severe weather. Ensuring the proper water level helps avoid these concerns, providing a secure base for the cover to protect your pool from debris, animals, and seasonal damage.
Can I adjust the water level after installing the safety cover?
Adjusting the water level after installing a safety cover is possible, but it requires careful handling to avoid damaging the cover or compromising its safety function. If adjustments are needed due to unexpected rainfall or temperature changes, a submersible pump can be used to remove excess water without lifting the cover entirely. However, any manipulation should be minimized to preserve the cover’s integrity and reduce the risk of tripping hazards.
Additionally, once the cover is installed and secured, it becomes harder to check pool levels without lifting the cover. Installing an automatic pool cover pump or using a manual pump to remove standing water can help maintain safe water levels under the cover. These pumps manage rainwater or melting ice without disturbing the cover, thereby preserving safety features and prolonging the product’s durability.
Should I drain the pool the same amount if I have a mesh versus a solid safety cover?
The type of safety cover—mesh or solid—can influence how much water you should leave in your pool. Mesh covers allow water to drain through them, significantly reducing the risk of water accumulation on top. Because of this ability, some pool professionals advise only lowering the water by about 12 inches from the top of the pool, ensuring the cover is taut but doesn’t sag appreciably.
Solid safety covers, on the other hand, hold water and debris on the surface, requiring more attention in terms of drainage. To safely use a solid cover, the pool should usually have the water level lowered further—anywhere from 18 to 24 inches depending on the local winter climate. This allows space for ice and rainwater to accumulate without reaching skimmer openings or compromising the cover’s fit.
How does climate affect the proper water level when closing a pool with a safety cover?
Climate plays a significant role in determining how far to drain your pool before installing a safety cover. In regions that experience freezing temperatures, the pool must be drained enough to prevent water expansion from damaging skimmers and pipes. The colder the climate, the lower the water level should be to account for ice growth and snow melt accumulation on the safety cover.
In milder climates with little to no freezing weather, fewer drainage precautions are needed, and water levels can be kept slightly higher. Water levels just a few inches below the skimmer may suffice because there’s less risk of ice damage. However, even in warm regions, maintaining the right level ensures that rain and debris do not overfill the pool and lift the safety cover, which can pose a risk to both the pool and surrounding landscape.