An inground pool is a significant investment, both financially and in terms of maintenance. Many homeowners find themselves questioning how long they can leave their pool drained or empty—whether due to a planned renovation, cleaning, or an unexpected circumstance. However, leaving a pool empty for an extended period can pose serious risks to its structure and longevity. This article explores the various types of inground pools, the potential dangers of leaving them empty, and best practices to follow when draining your pool.
Understanding the Different Types of Inground Pools
Before diving into how long you can leave a pool empty, it’s important to understand the different materials used in inground pool construction. Each type reacts differently to being drained, and the structural integrity can be affected in unique ways.
Concrete (Gunite) Pools
Concrete, or gunite pools, are among the most durable inground options. These pools are constructed by spraying a concrete and sand mixture over a rebar framework. Once cured, the interior is coated with plaster, tile, or another finish.
Why Emptying a Concrete Pool Can Be Risky
Concrete pools are designed to withstand the hydrostatic pressure from both the water inside and the ground surrounding them. When the pool is emptied, the groundwater outside may create a buoyant force that can lift or “pop” the pool out of the ground. This can cause serious structural damage, including cracks in the shell.
Vinyl Liner Pools
Vinyl liner pools feature a flexible PVC liner installed over a formed structure made of steel, polymer, or aluminum walls. These pools are known for their comfort underfoot, versatility, and cost-effectiveness compared to concrete pools.
Vinyl Liner Risks When Pools Are Empty
Leaving a vinyl pool empty can cause the liner to dry out, shrink, or wrinkle. Once damaged, the liner can be costly to replace. Liners are also vulnerable to punctures when the pool is empty, especially if homeowners or workers are stepping inside.
Fiberglass Pools
Fiberglass pools are pre-molded shells made from layers of fiberglass, gelcoat, and resin. They are known for their smooth surface, low maintenance, and quick installation.
Why Fiberglass Pools Shouldn’t Be Left Dry for Long
These pools are particularly sensitive to buoyancy. If the water is removed and groundwater levels rise, the lightweight structure can literally “float” out of the ground. Additionally, without water to counterbalance the pressure from the surrounding soil, structural warping could occur.
How Long Can You Safely Leave Your Pool Empty?
Now that we understand the structural differences, let’s explore how long you can realistically leave your pool water-free without risking significant damage.
General Timeframe for Each Pool Type
| Pool Type | Maximum Time Typically Safe to Leave Empty | Common Risks |
|---|---|---|
| Concrete (Gunite) | 7–14 days | Hydrostatic pressure damage, cracking |
| Vinyl Liner | 7–10 days | Liner wrinkles, tears, punctures |
| Fiberglass | Up to 7 days | Buoyancy issues, warping |
It’s important to note that safety timeframes are theoretical and highly dependent on environmental factors like water table levels, soil composition, and local weather conditions.
Signs You Should Not Leave the Pool Empty
- Extended rainy periods or high water table levels
- Low-quality or aging construction
- Pools located near large trees or natural water sources
If the soil around your pool is already saturated, the risk of hydrostatic pressure overwhelming the empty pool increases dramatically.
Why Pools Should Not Be Left Empty
Leaving an inground pool empty can lead to more than aesthetic or functional issues. It can cause major structural damage that requires costly repairs—or in severe cases, complete replacement.
Hydrostatic Pressure and Pool Displacement
The soil around the pool can become saturated with water from heavy rain or a high water table. This groundwater exerts upward hydrostatic pressure, especially when the pool is empty. If the force becomes strong enough, it can “float” the pool, lifting it out of the ground and causing:
- Cracks in the pool walls or floor
- Damage to plumbing and underground utilities
- Disruption to deck and patio
This phenomenon is more common than many realize—especially for fibreglass and vinyl pools—and in some areas, it has led to entire pools being displaced.
Vinyl Liner Deterioration
Vinyl pools are especially susceptible to damage when empty. Once drained, the liner can slip, stretch, or tear. UV exposure can also accelerate degradation, breaking down the material and shortening its lifespan. Liners that have dried out are harder to reshape and typically cannot be installed properly again.
Pool Finishing Damage
Concrete pools often have a plaster or aggregate finish on the interior surface. When exposed to air for too long, especially in dry or sunny climates, the finish can dry out, crack, or lose adhesion. This creates an uneven surface that may require replastering, which can cost thousands of dollars.
Impact on Pool Equipment
Leaving a pool drained might also affect your pool’s filtration equipment, pumps, and heaters. These devices are designed for continual water circulation. When left unused for too long, rust or corrosion may occur, and seals can dry out, leading to leaks or mechanical failure when they are reactivated.
When Is It Okay to Drain an Inground Pool?
While keeping a pool filled is ideal, there are circumstances when draining a pool becomes necessary or recommended.
Pool Renovations and Repairs
One of the most common reasons for completely draining a pool is to perform major repairs or renovations, like:
- Replastering concrete walls
- Refurbishing coping and decking
- Replacing the vinyl liner
- Repairing major plumbing issues
In these cases, full drainage may be required, even if it’s risky. However, precautions should be taken, such as installing hydrostatic relief valves or monitoring groundwater levels.
Severe Contamination or Algae Infestation
If your pool has experienced persistent algae blooms or chemical contamination that standard treatments can’t eliminate, partial or full draining might be necessary. However, most infestations can be addressed through thorough cleaning, shock treatments, and filtration—without having to fully drain the structure.
Winterization in Cold Climates
In some regions, pool owners must winterize their pools, which involves lowering the water level and disconnecting equipment instead of completely draining. In this scenario, partial draining and winter covers protect against freezing damage, while retaining enough water to counteract buoyancy.
Best Practices: Draining a Pool Safely
If you must drain your pool—whether for renovations, repairs, or emergencies—there are critical steps to ensure it remains secure and intact.
Monitor Groundwater Levels
Before draining your pool, reach out to local contractors or check your city’s water table reports. High-water seasons, especially after snow melts or during heavy rains, are not ideal times for full draining.
Use Proper Equipment
It’s vital to use a professional-grade pump designed for pool water removal. Improper pumps or drainage techniques can delay the process or contribute to equipment damage.
Keep an Eye on Weather Forecasts
If a storm or heavy rainfall is expected during the time your pool is empty, reconsider the draining plan. Soil saturation can quickly lead to buoyancy.
Use Hydrostatic Relief Valves
For concrete pools, adding or activating hydrostatic relief valves can help equalize pressure and prevent displacement. These valves allow groundwater to enter the pool basin if hydrostatic pressure builds up.
Do Not Leave the Pool Empty Overnight (If Draining Temporarily)
If you’re performing temporary cleaning or maintenance, try to keep the water level above the skimmer, or cover the pool and complete the task quickly to avoid structural risks.
Consider Partial Draining
In many cases, a full drain isn’t necessary. Partial draining allows you to access deeper sections of the pool while retaining enough water to maintain structural integrity and reduce buoyancy risk.
What to Do After Your Pool Is Empty
Whether your pool has been drained for repairs, cleaning, or maintenance, getting it back into working condition requires preparation and planning.
Inspect for Structural Damage
During the time the pool was empty, check for any cracks, warping, or shifting. This includes examining the floor, walls, and coping. For vinyl pools, ensure that the liner remains intact and hasn’t pulled away from the edges.
Clean the Interior Before Refilling
Use a mild acid wash, wet vacuum, or pressure washer to remove any minerals or residue. This helps ensure cleaner water once the pool is refilled.
Restore Equipment Functionality
Before beginning the refill process, check all your pool equipment. If the filter, pump, or heater has been idle for an extended period, inspect for leaks, corrosion, or seal damage.
Refill With Clean, Balanced Water
When refilling, it’s advisable to test the municipal or well water for hardness, pH, and other chemical properties. This helps in determining how much chemical adjustment will be needed afterward.
Balance the Chemistry Immediately
Once water reaches the appropriate level, start treating the water with chlorine or other sanitizers. Test the water regularly for pH, alkalinity, and calcium hardness to protect surfaces and ensure safe swimming conditions.
When in Doubt, Call a Professional
Trying to figure out how long you can leave your inground pool empty depends on numerous factors—your location, the type of pool you own, the surrounding soil, and even the time of year. Before draining your pool completely, it’s always best to consult with a professional pool contractor or technician.
Many experts can guide you on whether a full drain is necessary, when it’s safest to proceed, and how you should protect your pool while it’s empty. Investing in a professional opinion could prevent costly damage and keep your pool in excellent condition year after year.
The Bottom Line
Leaving an inground pool empty for extended periods is risky and should be avoided unless absolutely necessary. Time limits vary by pool type, but all inground pools face threats like hydrostatic pressure, structural damage, and liner issues when water is removed. If renovations, repairs, or deep cleaning call for draining your pool, ensure you take protective measures and complete the work within the recommended timeframe.
Remember, your pool represents a significant portion of your home’s outdoor value. Proper care and informed decisions about draining it will help prolong its life and maintain its functionality and beauty for years to come.
Plan, Protect, and Proceed with Caution
Knowledge is your greatest tool in protecting your investment. Whether you’re looking to conduct deep cleaning or a major renovation, understanding how long a pool can be empty and what conditions to monitor can make all the difference between a simple project and a costly disaster. Always proceed with caution, take preventive measures, and keep your pool maintenance plan tailored to your specific pool type and local environment.
How long can you safely leave an inground pool empty?
The safe duration for leaving an inground pool empty largely depends on the type of pool and environmental conditions. Generally, concrete pools can withstand being empty for a few days if the structure is sound and the weather is relatively stable. However, keeping them empty for extended periods can lead to serious issues like hydrostatic pressure causing the pool to pop out of the ground, especially in areas with high water tables.
Vinyl and fiberglass pools are even more sensitive to being left empty and should not be drained except for specific maintenance reasons. Vinyl pools risk the liner drying out, shrinking, or tearing when exposed to sunlight and heat, while fiberglass pools can shift or crack if not properly supported. As a rule of thumb, if draining is necessary, it’s best to complete the task as quickly as possible and refill the pool promptly to avoid complications.
What are the risks of leaving a pool empty for too long?
Leaving a pool empty for an extended period can lead to several structural and maintenance risks. One of the most common dangers, particularly in concrete pools, is hydrostatic pressure. When groundwater rises, it can exert pressure from beneath, lifting or “floating” the pool structure, causing cracks or even extensive damage. This is especially common during rainy seasons or in areas with high water tables.
Additionally, empty pools are exposed to the elements and face issues like UV damage to vinyl liners, shifting or cracking of fiberglass shells, and the buildup of debris. The absence of water also removes the natural pressure that helps keep certain parts of the pool, like the walls and plumbing, in place. Over time, this can result in costly repairs, even rendering the pool unsafe or unusable without extensive renovation.
Can winter conditions impact how long I can leave my inground pool empty?
Winter conditions can significantly limit the time you can safely leave an inground pool empty. When temperatures drop, the ground can freeze, leading to ground expansion and contraction. This movement can cause stress to the pool’s structure, especially if it is empty. This is particularly risky for concrete, fiberglass, and vinyl pools, all of which can suffer cracks or misalignments due to freezing conditions.
Moreover, residual moisture left behind after draining can freeze in the plumbing lines or equipment, causing pipes to burst or crack. In colder climates, leaving a pool empty for an extended period during winter without proper preparation is generally not recommended. If a pool must be emptied during winter, it should be properly winterized and, ideally, only emptied temporarily, such as during repairs or renovation projects that require it.
What precautions should I take if I need to drain and leave my pool empty?
If you need to drain your pool, there are several key precautions to take to minimize the risk of damage. First, consider the water table level in your area. A skilled pool technician can determine whether a dewatering system should be used to relieve hydrostatic pressure during draining. If the pool is being emptied during wet or rainy periods, this becomes even more critical to avoid upward pressure from groundwater.
Second, always ensure that pool covers, plumbing, and skimmers are properly secured or covered to prevent debris and rainwater from entering the empty structure. For vinyl pools, keep the liner moist to prevent it from drying or shrinking. Fiberglass pools should be inspected for signs of movement or stress. Additionally, consult local pool professionals or the manufacturer’s guidelines to ensure you’re taking the correct steps for your specific pool type.
How long can I leave a vinyl pool empty without damaging the liner?
Vinyl pools are particularly sensitive to being left empty, and ideally should not be completely dewatered unless absolutely necessary. The vinyl liner is designed to stretch when filled with water and remain in place due to consistent pressure. When the pool is empty, especially under direct sunlight or heat, the liner can dry out, shrink, and ultimately tear or warp when it’s reinstalled. Most experts recommend not leaving a vinyl pool empty for more than 24–48 hours.
Furthermore, draining a vinyl pool for extended periods can also affect the surrounding structure, including the walls and supports. Without water, these elements can shift or bow, leading to misalignment when re-filling. To minimize damage, always keep the liner moist, avoid exposing it to excessive heat, and try to refill the pool as soon as possible after any necessary repairs or maintenance.
Can I leave my fiberglass pool empty for a few days without issues?
In general, fiberglass pools can handle being empty for a few days, especially if they are in good condition and you’re performing repairs or cleaning that require temporary draining. However, because fiberglass pools are lightweight and molded into shape, they are more prone to structural stress when empty. One key concern is “floating” due to groundwater pressure, which can cause the pool to lift or shift within the ground.
Another important precaution is to monitor temperature and humidity levels, as extreme conditions can affect the integrity of the pool shell. If draining a fiberglass pool, make sure to do so under the guidance of a professional, who can assess whether dewatering systems are needed or whether supports should be installed to maintain the structure’s integrity during the draining period.
What should I do if I accidentally left my pool empty for too long?
If you’ve accidentally left your pool empty for an extended period, the first step is to assess any visible damage. Check for cracks in concrete pools, warping or shrinkage in vinyl liners, or shifting and stress lines in fiberglass pools. Look for signs of water intrusion beneath the pool or within the surrounding deck area. If there are apparent structural issues, it’s best to consult a professional pool contractor before proceeding.
If there are no obvious signs of damage, consider filling the pool gradually while monitoring for any changes. Ensure the skimmer and return lines are properly prepared, and run water into the pool through a hose to limit the risk of pressure imbalance. If your pool has a hydrostatic valve, consult a technician before allowing it to operate again. Once refilled, you should test and balance all chemical levels before using the pool again.