When you own a swimming pool, one of the biggest concerns is ensuring it functions properly and remains structurally sound. But what happens if the water needs to be drained or is lost unexpectedly? How long can a pool be without water before problems arise? This question is essential for homeowners, pool builders, and service providers alike.
This article dives into the critical factors that influence how long a pool can be left dry, the types of pools and their vulnerabilities, potential damage risks, and best practices to ensure structural and chemical integrity when a pool goes empty — whether temporarily or for extended periods.
Understanding Why a Pool Might Go Without Water
There are multiple scenarios in which a pool may be left without water, both intentional and unexpected. These include:
- Seasonal pool closures: Especially in colder climates, pool owners may prefer to drain water for the winter season.
- Renovation and repair: Structural maintenance or resurfacing often requires a pool to be drained.
- Unexpected leaks: Major cracks or pipe failures can drain a pool overnight.
- Construction errors: Poor workmanship during installation can result in pools that cannot hold water immediately.
- Chemical overload or contamination: If chemical imbalances reach dangerous levels, some professionals recommend draining the pool.
Each of these situations presents unique challenges when it comes to maintaining the pool structure and minimizing damage.
Different Types of Pools and Their Vulnerability to Being Empty
Not all pools respond to being drained in the same way. The construction and design of the swimming pool determine its tolerance to being left empty for an extended period.
1. Concrete / Gunite Pools
Concrete or gunite pools are the most common in-ground pools. Their construction involves steel rebar (“reinforcing bars”) embedded in concrete. These pools can remain empty, but only for a limited time — usually not more than 7–10 days. Without water, there’s increased risk due to:
- Hydrostatic pressure: Groundwater can push the pool structure upwards (“hydrostatic uplift”) if it’s not properly anchored and the water table is high.
- Structural stress: Concrete pools are built to be supported by hydrostatic pressure from water; without it, the shell can crack from tension and stress fluctuations.
In-ground concrete pools should ideally have hydrostat plugs or hydrostatic relief valves to manage groundwater pressure if the pool is drained.
2. Vinyl Liner Pools
Vinyl liner pools, which are typically in-ground with a metal or polymer wall structure, are highly vulnerable to damage when emptied:
- Linings warp or shrink when left dry.
- Metal walls are prone to rusting in damp, cold conditions after draining.
- Skimmer and return fittings may rust, warp, or corrode without water to maintain hydration.
Vinyl liner pools should not be left empty for longer than a few days, especially outdoors where environmental impact is rapid.
3. Fiberglass Pools
Fiberglass pools are pre-molded and placed in the ground during installation. They’re known for their durability and seamless liners.
However, these pools are uniquely at risk when empty due to:
- The material’s flexibility: Without water to support the structure, fiberglass pools are prone to shifting or buckling underground — especially if the water table rises.
- Lack of structural reinforcement: Unlike gunite, fiberglass pools rely on the surrounding soil support for equilibrium, which can be disturbed when left empty.
It’s recommended that fiberglass pools be empty for no more than 1–2 days without support or structural precautions.
4. Above-Ground Pools
Most above-ground pools have metal, resin, or hybrid wall structures with vinyl liners. When emptied:
- Metal structures are easily corroded from exposure to humidity and temperature changes.
- Vinyl liners may dry out, crack, or become brittle without moisture preservation.
These pools can generally remain empty over winter (if completely disassembled and stored) but shouldn’t be left dry and open for months without protection.
How Long Can You Leave a Swimming Pool Empty? Time Limits Based on Pool Type and Environment
The optimal drying time for in-ground and above-ground swimming pools varies significantly according to location, pool type, and groundwater conditions. Below is a summary table outlining estimates:
| Pool Type | Maximum Recommended “Empty” Duration | Common Risks |
|---|---|---|
| Concrete/Gunite | 7–10 days (with proper groundwater control) | Hydrostatic upheaval, shell cracking, dry filtration stress |
| Vinyl Liner | 3–7 days | Liner shrinkage/warping, metal rusting, wall distortions |
| Fiberglass | 1–2 days (maximum 5 days with caution) | Structural shifting, buckling, wall collapse |
| Above-Ground (vinyl/metal) | Up to 6 months if drained and winterized | Liner degradation, corrosion, metal fatigue |
Climate Considerations: Environmental Impact on Drained Pools
The environment your pool is located in plays a critical role in how long it can remain unused or emptied. Pools in certain climates are more prone to damage due to:
High Groundwater Tables
In areas where the water table rises seasonally, such as in coastal or tropical regions, pools left empty may face hydrostatic issues. When empty, the pool’s structure could float or crack if groundwater rises below or inside the shell.
Hydrostatic pressure differences may cause damage in as little as 48–72 hours depending on soil porosity, groundwater level, and construction quality.
Dry or Desert Climates
In places with extreme sun exposure, like the Mojave Desert or desert climates of the Middle East, drained pools face rapid wear and chemical residue build-up. In such regions:
- Metal components can rust from temperature-driven condensation at night and sun damage by day.
- Stone or tile finishes might fade, crack, or become brittle from high UV exposure and thermal stress.
- Clogged drain systems may harden without moisture to maintain flow.
In these conditions, even temporary draining should take maximum precautions, like tarp covering and soil monitoring.
Freezing Temperatures
In cold climates such as those of Canada, Northern Europe, or mountainous regions of the US, water left in equipment or piping can freeze, crack, and break critical pool components even if the main structure is empty.
Pools left partially full in cold seasons risk the formation of ice damage, particularly in skimmers and jets, which then require costly repairs before refilling.
Dangers of Leaving a Pool Empty for Too Long
Many pool owners may think that draining the water temporarily is harmless — but without water, the structure is vulnerable to several types of irreversible damage.
Structural Damage
In-ground pools depend on water pressure to counteract soil pressure and groundwater buoyancy. Without water:
- Floors can lift, bow, or crack.
- Walls may warp — especially in vinyl and fiberglass pools.
- Expansion joints and tiles can come loose due to moisture and temperature shifts.
In severe cases, a pool may have to be completely rebuilt.
Loss of Liner Integrity
Vinyl-liner owners are particularly at risk with empty pools. Once drained:
- Liners can dry out and lose elasticity.
- Creases or folds formed without water pressure may remain permanent, leading to leaks upon refill.
- Color fading and mildew buildup can worsen, especially in humid environments.
Liner replacement costs can range from $1,500 to over $5,000 depending on pool size and quality.
Damage to Pool Equipment and Systems
Pool components like pumps, filters, heaters, and automation systems suffer in an empty pool environment:
- Filters and valves dry up and fail to re-initiate properly.
- Chemical feeders can corrode or calcify, especially chlorine and salt-based systems.
- Pumps without water may overheat and become damaged.
Soil and Foundation Shifts
Proper backfill and soil compaction are essential for in-ground pools. When the pool is left empty for an extended period, soil can shift or collapse around the structure.
In extreme cases, such as with unstable clay soils or water-saturated ground, empty pools may:
- Settle unevenly.
- Develop wall cracks.
- Require expensive underpinning or foundation correction.
Best Practices for Maintaining a Pool During Draining Periods
If you need to drain your pool — for repairs, refilling after contamination, or seasonal maintenance — it’s critical to follow the correct protocol to minimize risk.
1. Have the Correct Equipment Ready
Before draining your pool, make sure you have:
- A groundwater pressure monitoring device or professional technician to assess hydrostatic risk.
- Dewatering equipment, like sump pumps or submersible pumps.
- Professional pool service team for guidance and setup.
2. Covering the Pool Structure
Cover the empty pool with:
- Heavy-duty plastic tarpaulins to reduce dust accumulation and solar exposure.
- Supportive beams for vinyl or fiberglass walls if the draining period is expected to extend beyond safe limits.
These precautions reduce the chances of structural damage or liner degradation.
3. Use Water Sensors
For concrete pools, install water sensors in hydrostatic valve or footer regions, which can alert you to rising groundwater levels that may necessitate immediate water refill or emergency pumping.
4. Perform Regular Inspections
If your pool is empty for an extended time, periodic inspections by a certified technician are highly recommended. Signs to look out for include:
- Unusual ground moisture near the pool area.
- Cracked plaster (in concrete pools).
- Distorted vinyl or fiberglass surfaces.
- Signs of rusting or clogged equipment.
5. Refill Promptly When Conditions Permit
Once service is completed or repairs are finished, refill the pool quickly. Refilling after long emptiness should always be done slowly with attention to:
- Ground displacement risks.
- Hydrostatic pressure buildup.
- Water chemistry treatment to avoid calcium scaling and corrosion.
When Should You Consult a Pool Professional?
Draining your pool improperly can lead to costly damage — and in extreme cases, loss of the entire structure. When in doubt or in the following situations, it’s best to consult a local pool service professional:
- Unidentified signs of structural cracking or wall movement.
- Uncontrollable rises in groundwater while the pool is empty.
- High humidity or freezing weather affecting metal or vinyl components.
- Uncertainty about filtration system integrity after long periods of dry storage.
An expert can help assess the risks and possibly offer temporary hydrostatic buoyancy solutions, such as installing a support water bladder or soil pressure barriers.
In Conclusion: Know the Limits of an Empty Pool
In summary, how long a pool can be without water is not a simple one-size-fits-all answer. It hinges on multiple factors including:
- The type of pool — whether concrete, vinyl, fiberglass, or above-ground.
- Climate and groundwater conditions — both seasonal variability and regional factors.
- The reason for draining — temporary cleaning, extensive repairs, or seasonal storage.
- Maintenance practices during the drainage — covering, monitoring, and upkeep of equipment and liners.
By understanding how long your specific pool can safely remain without water, you’re better equipped to protect your investment and avoid expensive structural damage. Whether dealing with an unexpected water loss or scheduling planned maintenance, planning ahead and seeking professional guidance can make all the difference.
If you’re preparing to drain your pool — whether for maintenance, construction, or relocation — never underestimate the importance of professional support. And remember: pool maintenance is as much about water levels and chemicals as it is about structural integrity and seasonal preparedness.
Knowing your pool’s limits when it’s empty could very well preserve your backyard oasis for years to come.
What happens if a pool sits without water for too long?
Leaving a pool without water for an extended period can lead to serious structural and maintenance issues. Without water, the pool’s surface can dry out and crack—especially in concrete or vinyl-lined pools—where the materials are designed to remain hydrated or supported by water pressure. Exposed plaster can chip or delaminate, and vinyl liners may shrink or become brittle. Additionally, the lack of water can allow hydrostatic pressure from groundwater to push the pool upward, potentially causing it to pop out of the ground in severe cases, particularly with inground models.
Proper winterization or emptying procedures should always include the use of equalization valves to prevent groundwater-related damage and the placement of a protective cover to minimize debris accumulation. For above-ground pools, the structure may collapse inward or warp without the support of water. Furthermore, pool equipment such as filters, pumps, and heaters can be damaged if not properly winterized or drained. Thus, leaving a pool dry for too long without taking precautions can lead to costly repairs or even require total reconstruction.
How long can an inground pool safely be left empty?
An inground pool should generally not remain empty for more than a few weeks unless specifically designed or prepared for a longer period of disuse. Most manufacturers recommend that inground pools only be emptied temporarily for repairs, cleaning, or renovations, and even then, precautions must be taken to prevent damage. The allowable duration depends on several factors including soil conditions, the type of pool construction, and the water table in the area.
If groundwater is present, the empty pool can be subject to upward pressure that can cause cracks, shifting, or even catastrophic failure. Emptying a pool in an area with high water tables requires continuous dewatering during the period it remains empty. To safeguard against damage, it’s typically recommended to keep an inground pool filled or to follow the guidance of a professional who can ensure proper hydrostatic pressure balance using valves and pumping systems if necessary.
Can an above-ground pool be left empty during winter?
An above-ground pool can be left empty during winter, but only if it is completely dismantled and stored properly. If the pool structure remains in place and is not fully taken down, leaving it empty can be risky. Without water, the metal or polymer walls may warp, collapse, or become damaged due to harsh weather, snow accumulation, or strong winds. Most above-ground pools rely on the water’s weight and pressure to maintain their shape and stability throughout the year.
For seasonal pools, the typical solution is to either completely disassemble the pool and store its components indoors or keep the structure filled with water and properly winterized. If you have a permanent above-ground pool that cannot be easily deconstructed, it’s usually best to maintain it like an inground pool—by balancing chemicals, adding a winter cover, and keeping water in it to prevent structural issues. The method depends on the design and manufacturer’s recommendations.
What are the risks of draining a pool for an extended period?
Draining a pool for an extended period exposes it to multiple risks, the most serious of which is structural damage due to groundwater pressure. In areas with a high water table, groundwater can push up through the base and sides of an empty pool, leading to cracks, shifting, or even the entire pool being lifted out of the ground. This is particularly common with concrete and fiberglass inground pools. Another significant concern is the deterioration of the pool’s surface and components such as the plaster, tiles, or vinyl liner, all of which are designed to remain submerged or at least moist.
In addition to physical damage, draining a pool can result in equipment damage if not properly winterized. Filtration systems, heaters, and plumbing lines may be compromised by freezing temperatures or corrosion due to stagnant moisture. Algae and bacteria can also flourish in an empty pool if it’s exposed to humid conditions and frequent rainfall. These contaminants can stain surfaces and add to the cleaning and restoration workload when refilling the pool, making it more expensive and time-consuming to reinstate.
How can I protect my pool if I need to drain it for maintenance or repairs?
If you need to drain your pool for any reason, the first step in protecting it is to consult a professional, especially for inground pools. Hydrostatic pressure can be a major concern, so installing hydrostatic relief valves is crucial in areas with high groundwater levels. Covering the empty pool with a durable, tightly-fitted pool cover will help keep out debris and prevent accidental damage from weather or animals. Additionally, placing a sump pump nearby can help manage any rising groundwater during the period the pool is empty.
For the pool structure itself, it’s important to address any cracks or surface issues before draining to avoid accelerated damage. If exposed surfaces like plaster or tile start to dry out, applying a moist mister or spraying light water mist can help prevent premature cracking. Equipment should be properly blown out and stored or winterized to avoid internal freezing or corrosion. Taking careful steps when emptying the pool ensures it remains in stable condition until it can be safely refilled and reactivated.
Is it okay to leave a pool empty for a few days?
Leaving a pool empty for a few days, such as during cleaning or minor repairs, typically does not pose a significant risk, especially if the weather is mild and groundwater levels are low. Short-term draining for tasks like resurfacing, leak repair, or equipment replacement can usually be done safely with minimal precautions. However, it’s still wise to take steps such as covering the pool to limit the buildup of debris and protecting exposed areas from direct sunlight or unexpected rain.
That said, even within a few days, the potential for damage depends largely on the specific environment and pool type. Fiberglass and vinyl-lined pools are particularly vulnerable to sun damage and warping when exposed. If temperatures drop at night, condensation and moisture inside the pool shell could lead to mold or mildew growth if the structure isn’t ventilated properly. While short-term draining is generally acceptable, it’s important to be aware of the conditions that may affect the pool when water is removed.
How does leaving a pool empty affect maintenance costs in the future?
Leaving a pool empty for an extended period can significantly increase future maintenance and repair costs. Structural issues such as cracking, surface delamination, liner damage, or equipment failure can occur when the pool is without water for too long. These problems often require costly professional repairs—sometimes even complete renovations—if the damage is extensive. In particular, inground pools are prone to shifting when empty, which can lead to re-levelling or foundation stabilization costs.
Additionally, pools left without water may accumulate dirt, algae, and other contaminants that require an intensive cleaning process before the pool can be used again. This may involve acid washing or replastering, which adds to the overall expense. Chemical balance and system efficiency may also be affected once the pool is refilled, requiring recalibration of filtration components or replacement of corroded pipes and valves. To minimize long-term costs and ensure the pool remains operational, it’s wise to avoid draining the pool unnecessarily and to implement protective measures when draining is unavoidable.