Inground pools provide a refreshing escape during warm weather, but there are times when draining them becomes necessary—whether for repairs, cleaning, or major renovations. However, leaving an inground pool drained for an extended period isn’t without risk. Understanding how long you can safely keep your pool empty requires knowledge of both the type of pool and the environmental conditions involved.
In this article, we’ll explore how long different types of inground pools can safely remain drained, the dangers associated with prolonged draining, the effects of weather and water table conditions, and how to properly maintain a drained pool to avoid costly damage.
Why Would You Drain an Inground Pool?
Before diving into how long you can leave a pool drained, it’s important to understand the reasons behind draining a pool. While it’s not something pool owners do frequently, there are valid situations that may require you to empty an inground pool completely.
Routine Maintenance and Cleaning
Over time, pool surfaces accumulate scale, stains, and mineral deposits that can’t always be removed through normal cleaning processes. A full drain allows for deep cleaning and re-plastering, which rejuvenates the interior surface.
Structural Repairs
Cracks in the pool structure, leaks in the plumbing, or damage to the gunite or vinyl require repairs that are often easier or safer to perform on a completely empty pool.
Chemical Imbalances
Extremely high levels of total dissolved solids (TDS), calcium, or other chemical imbalances may result in water that is unresponsive to normal treatments. Draining is the only way to restore chemical balance in some cases.
Refurbishment or Renovation
Pool owners upgrading their pool features—like adding a tanning ledge, changing tile, or modifying the coping—often need to completely drain the pool to facilitate these changes.
How Long Can You Leave an Inground Pool Drained?
The answer to how long a pool can safely remain empty depends largely on the type of pool, local climate, and the water table in your area. Let’s break it down by pool type.
Concrete (Gunite or Shotcrete) Inground Pools
Concrete pools, which are typically constructed using gunite or shotcrete, are more durable than other inground pools. However, they’re not immune to damage when empty for long periods.
Maximum Recommended Draining Time: 7 to 10 days
Concrete pools have a plaster surface that can dry out and crack if left unhydrated. Additionally, if exposed to freezing temperatures, structural components can be damaged. Some areas may allow slightly longer drain times (up to 14 days) in mild weather, but exceeding this time frame is risky.
Factors Influencing Drain Time for Concrete Pools:
- Clarity of instructions from the manufacturer or contractor
- Presence of a high water table (risk of floating)
- Surface materials (plaster, quartz, pebble)
- Use of a pool cover or shading
Vinyl Liner Inground Pools
Vinyl liner pools are more sensitive to being left empty due to the nature of the material. The liner can dry out, shrink, or become brittle if exposed to the sun and air for too long.
Maximum Recommended Draining Time: 5 to 7 days
Some pool experts recommend draining only long enough to complete the necessary project—sometimes just 1 to 2 days if possible—to avoid damage. Vinyl liners are also prone to stretching when refilled, especially in hot weather.
Common Issues with Draining Vinyl Pools:
- Liner becomes dry and inflexible
- Water table may push the liner upward or distort the pool walls
- Dust buildup makes it harder to clean before refilling
- Increased risk of tearing when reinstalling and realigning the liner
Fiberglass Inground Pools
Fiberglass pools are designed to be watertight from the start, and their smooth, durable surface resists damage better than plaster or vinyl. However, they still require care when drained.
Maximum Recommended Draining Time: Up to 14 days
Fiberglass pools can be more resilient to drying out than other materials, but problems arise in areas with a high water table or extreme temperatures.
Precautions for Fiberglass Pools:
- Check water table levels before draining
- Use support braces during long drains (if recommended by manufacturer)
- Avoid direct sunlight exposure by using covers or tarps if extended draining is unavoidable
Key Risks of Leaving an Inground Pool Empty Too Long
Understanding the potential damage caused by excessive draining will help you make informed decisions about how long to leave your pool empty.
Potential for Structural Damage
Water pressure isn’t just internal. Groundwater surrounding the pool may exert upward pressure when the pool is empty. This can cause the pool structure to “float” upward, leading to severe structural damage, including:
- Cracks in the pool walls and floor
- Displacement of plumbing lines
- Warping of the overall structure
This is a particular concern for those in areas with high water tables or underground springs.
Drying Out and Cracking of Plaster and Concrete
If a concrete or gunite pool remains empty too long, especially in warm or dry conditions, the plaster can lose moisture rapidly and develop hairline cracks. These cracks not only look unsightly but also promote water leakage and algae growth after refilling.
Liner Damage in Vinyl Pools
Vinyl liners need moisture to retain flexibility. Once they dry out and lose elasticity, refilling the pool can result in:
- Liner tears
- Wrinkling and bunching that can’t be corrected
- Stretching beyond the elastic limit of the material, leading to sagging
Buildup of Dirt and Debris
Empty pools attract dust, leaves, pollen, insects, and sometimes even small animals. Cleaning debris from a dry pool is time-consuming and can lead to staining if not addressed before refilling.
Mold and Algae Growth
Moisture trapped in the cracks or corners of an empty pool can foster mold and algae growth. These contaminants must be thoroughly removed before refilling, otherwise they’ll compromise water quality and create additional maintenance issues.
Environmental and Geographical Factors That Influence Draining Duration
Where you live plays a big role in how long you can safely leave your inground pool empty.
Water Table Levels
In areas with a high water table—such as near rivers, lakes, or in low-lying areas—groundwater pressure can be enough to lift a drained pool from the ground. This phenomenon, known as “hydrostatic buoyancy,” poses a significant risk to all types of inground pools.
To combat this, some pools are equipped with a hydrostatic relief valve or a backfill sump. These features reduce the risk by allowing groundwater to enter the pool basin and balance the pressure. Even with such systems, limiting drainage duration is crucial.
Climate Conditions
Hot and dry climates can accelerate the drying and cracking of plaster in concrete pools, while humid and warm areas are more likely to promote mold and algae growth. In freeze-prone climates, even a small amount of moisture left in equipment or underground pipes can lead to freezing and damage.
Seasonal Considerations
Draining during shoulder seasons—such as late spring or early fall—can give you more flexibility in time because of moderate temperatures and reduced groundwater levels. Pool professionals recommend scheduling major repairs during these times to reduce risk.
How to Safely Drain and Maintain an Inground Pool
Follow these steps to minimize risks and maintain the integrity of your pool during a complete or partial drain.
Step 1: Consult a Professional
Before draining your pool, especially for extended periods, consult a licensed pool professional. They can provide specific guidelines for your pool type, local water table conditions, and climate.
Step 2: Clean the Pool Before Drainage
Remove all debris, brush the walls and floor, and ensure optimal water clarity before initiating drainage. This lessens the amount of cleanup needed while dry.
Step 3: Use the Correct Drainage System
Pools should be drained using a high-capacity pool pump or submersible pump designed for this purpose. Only use hoses and drainage methods permitted in your area—discharge water to sewers or lawful storm drains to comply with local water disposal regulations.
Step 4: Monitor Groundwater and Use Relief Systems
If your area has a high risk of groundwater buoyancy:
- Ensure your pool’s hydrostatic relief valve is functioning
- Do not seal or cover the main drain during drainage
- Drain gradually and monitor the surrounding ground and pool structure
Step 5: Cover or Protect the Pool
While it’s not always possible, using a tarp or temporary cover can:
- Control dust and debris accumulation
- Reduce sun exposure that dries out materials
- Prevent algae growth in shaded pool areas
Step 6: Schedule Repairs or Refill Promptly
Avoid leaving the pool empty longer than necessary. Start repairs quickly and refill within the recommended timeframe to avoid material damage.
When Not to Drain Your Pool
There are certain situations where draining your pool could do more harm than good.
High Water Table
If your area experiences a high water table, draining the pool can be unsafe. Doing so without taking proper precautions could cause the entire structure to rise, leading to costly repairs and loss of warranty coverage.
Unstable Weather Conditions
Plan your drain during dry and stable weather whenever possible. Storms and sudden temperature changes can introduce unexpected complications.
Lack of Proper Permits or Equipment
Some municipalities restrict draining pool water into streets or yards due to chemical content. Ensure you have a safe and legal method of water disposal before starting the draining process.
Pool Warranty Considerations
Some pool warranties come with clauses restricting DIY draining or specifying manufacturer-approved procedures. Draining your pool without adherence to these guidelines could void your warranty.
The Cost of Improper Draining
Leaving a pool drained for too long can lead to:
Expensive Structural Repairs
If your pool shifts due to water table pressure or develops cracks in the plaster, concrete, or fiberglass layer, the costs can easily run into thousands of dollars.
Replacement of Liners
For vinyl pools, a damaged or misshaped liner requires full replacement, which can cost between $1,500 and $5,000 depending on size and quality.
Professional Restoration Services
In some cases, even when the pool is intact, mold remediation, surface restoration, or chemical balancing after improper draining may need to be handled by a professional—adding to the bottom line.
Loss of Warranty
Ignoring manufacturer or contractor guidelines about drainage can void warranties on pool liners, surfaces, or the structure itself.
Conclusion: Balancing Safety, Time, and Practicality
Knowing how long you can leave an inground pool drained is essential for protecting your investment and avoiding costly repairs. As a general guide:
- Concrete pools: No more than 7 to 10 days
- Vinyl pools: Maximum 5 to 7 days
- Fiberglass pools: Up to 14 days, depending on environmental conditions
Always take into account local groundwater levels, climate conditions, and manufacturer instructions before draining your pool.
Smart pool ownership means draining only when absolutely necessary and always within a safe timeframe. If you’re ever unsure, contacting a certified pool specialist is the best way to ensure your inground pool remains structurally sound, visually appealing, and ready for the next swim season.
Can you leave an inground pool empty for a long time?
Leaving an inground pool empty for an extended period is generally not recommended due to several potential issues. Without water, the hydrostatic pressure from the surrounding groundwater can push the pool structure upward, leading to serious structural damage, especially in areas with high water tables. Additionally, the lack of water can cause the pool walls and surface materials like plaster to crack or deteriorate under temperature fluctuations and physical stress.
The duration a pool can safely remain empty typically depends on its construction type, location, and local groundwater conditions. Most professionals advise against leaving a pool drained for more than a few days unless preventive measures are taken, such as installing a hydrostatic relief valve or backfilling with material to support the structure. Always consult with a pool professional before completely draining your pool for an extended time.
What are the risks of draining an inground pool?
Draining an inground pool poses several risks, the most severe being structural displacement caused by groundwater pressure. When an inground pool is empty, the surrounding soil may still hold a significant amount of water, which can exert upward force on the pool floor and lead to it popping out of the ground. This is especially common after heavy rains or in areas with high water tables, and correcting such damage can be costly and complex.
Another risk involves damage to the pool’s surface and lining. Materials like plaster, concrete, or vinyl can dry out and develop cracks, tears, or warping when not submerged in water. Additionally, pool equipment such as filters, pumps, and heating systems may be damaged if used without water. Draining also accelerates the buildup of algae and staining when the pool is refilled, making reconditioning more labor-intensive and expensive.
How long can you safely leave an inground pool drained for maintenance or repairs?
For minor maintenance or repairs like resurfacing or tile cleaning, an inground pool can usually be safely drained for 8 to 12 hours if the weather is hot and dry. However, if the repair requires more time—such as fixing cracks, replacing a liner, or working on plumbing—it’s important to take precautions. Covering the pool or using misting systems to keep surfaces moist can help prevent drying and cracking.
Structural concerns still apply, so monitoring groundwater levels is crucial. In some cases, professionals will use ballast or backfill within the pool to maintain balance while it’s empty. They may also pump water from the surrounding environment to keep pressure levels safe. It’s best to plan repairs carefully and drain the pool only briefly and under professional supervision to minimize potential damage.
What should you do to protect your pool if you have to drain it?
If you must drain your pool, the first step is to consult a pool professional to understand the risks specific to your environment and pool type. Some pools are equipped with hydrostatic relief valves, which should be opened to allow groundwater to enter the pool structure and equalize pressure. This can prevent the pool from floating out of the ground, especially in wet seasons or areas with high water tables.
In addition to managing ground pressure, it’s important to keep pool surfaces wet if the water will be out for an extended time. Using a garden hose to regularly mist the walls or covering them with damp burlap sacks can help prevent cracking of plaster or concrete. If possible, keep the process short—within a day if you’re doing a quick clean or chemical adjustment—and make sure you follow proper re-filling procedures afterward, including balancing the water chemistry.
Can freezing temperatures affect a drained pool?
Yes, freezing temperatures can significantly affect a drained inground pool, especially if any moisture remains on the interior surfaces. When water inside the pool’s structure freezes, it can expand and create cracks in the walls or floor. Even small amounts of residual moisture trapped in small crevices can freeze and expand, leading to costly damage that may not be immediately visible.
It’s particularly important for pool owners in colder climates to understand the risks of draining their pool during the winter months. If a complete drain is necessary, thoroughly dry the pool or use dehumidifying tools to prevent ice formation. Heaters or insulating covers can also be used temporarily. Always follow proper winterization steps if you’re preparing your pool for cold temperatures, which often includes maintaining water balance rather than draining entirely.
Does draining your pool save money on maintenance?
Draining an inground pool is not an effective way to save money on maintenance and can actually lead to higher costs in the long run. Without water, the pool is more vulnerable to damage that requires expensive repairs, such as cracks, algae growth, or structural displacement. Additionally, when you refill the pool, you must rebalance the chemical levels, often requiring costly treatments and labor-intensive cleaning processes.
Instead of draining, regular maintenance such as cleaning, filter operation, and chemical balancing helps keep pool costs lower and extends the pool’s lifespan. Covering the pool to reduce debris and evaporation can also minimize maintenance work. Draining should only be considered when repairs require it or in emergencies, and even then, it should be done carefully to avoid future expenses.
What are best practices when temporarily draining an inground pool?
Best practices for temporarily draining an inground pool start with consulting a professional to assess groundwater risks and structural integrity. If the water table is high, hydrostatic pressure could cause the pool to lift from the ground. A certified pool technician may recommend opening hydrostatic relief valves, backfilling certain sections, or draining the pool only partially rather than fully emptying it.
Timing is also crucial—try to drain the pool during mild weather to avoid temperature-related damage. Use wet rags or a misting system to keep surfaces moist if left empty for several hours. Also, ensure all pumps and filtration equipment are turned off and secured during the process to prevent mechanical damage. Always have a plan to refill and rebalance the water promptly to maintain the pool’s condition and reduce the risk of staining or algae buildup.