Is It OK to Leave a Pool Drained? Understanding the Risks, Benefits, and Best Practices

Leaving a pool drained is a decision many pool owners face at some point. Whether it’s due to maintenance, repairs, or simply the off-season, draining a pool may seem like a logical or even necessary step. However, it’s not a decision to be made lightly. In this comprehensive guide, we explore whether it’s OK to leave a pool drained, the short- and long-term implications, and the best practices to ensure your pool remains in top condition.

Why Would Someone Leave a Pool Drained?

There are several common reasons why a pool owner may consider leaving their pool empty:

• Seasonal closure in colder climates where winterization requires draining some or all of the water
• Structural repairs, such as fixing cracks, leaks, or resurfacing the pool shell
• Renovations or upgrades, like adding water features, new tiles, or changing pool lighting
• Prolonged absence or vacation homes where maintaining water chemistry isn’t practical

While these scenarios may justify draining a pool temporarily, understanding the implications of this action is crucial for avoiding damage and costly repairs in the future.

Types of Pools and Draining Considerations

Different types of pools respond differently to being drained:

Each pool type comes with specific risks and recommendations. Inground concrete pools, for example, can be especially vulnerable to hydrostatic pressure when empty, which may cause the entire structure to lift out of the ground.

Risks of Leaving a Pool Drained

While draining a pool might seem straightforward, the hidden risks can be significant, especially when the pool is left empty for an extended period.

Structural Damage

One of the most critical concerns when draining a pool is the possible structural damage caused by hydrostatic pressure. Groundwater in the surrounding soil can exert upward force on the pool shell when it’s empty. Over time, this pressure can cause inground pools—especially concrete and fiberglass—to shift, crack, or even “pop” entirely out of the ground.

Hydrostatic Pressure and Water Table Levels

Pools located in areas with a high water table are at greater risk. When the pool is emptied, the surrounding water has nothing to counterbalance it, potentially lifting or damaging the structure. This risk increases during or after heavy rains, when groundwater levels rise.

Damage to Pool Surfaces

For concrete pools, draining without proper precautions can lead to several surface-level issues:

• Plaster drying out and cracking—concrete pools often have a plaster finish that needs hydration to maintain integrity
• Cleaning and staining issues—once drained, residual chemicals can damage the surface if left to dry

Fiberglass pools can also develop problems when drained, particularly if not supported properly or left exposed to sunlight, causing the shell to fade or warp.

Issues with Pool Equipment

Even when the pool is empty, the surrounding equipment such as pumps, filters, and heaters must be winterized or protected. Leaving them exposed to freezing temperatures or debris can lead to long-term damage, requiring costly repairs or replacements the next season.

Unintended Environmental or Safety Hazards

Empty pools can become safety or legal hazards:

• Attracting pests or becoming a standing water source for insects like mosquitoes
• Risk of accidents—children or animals may fall into an uncovered drained pool
• City regulations prohibiting empty pools for safety and sanitary reasons

Many municipalities require that any pool—drained or filled—be securely fenced or covered when not in use.

When Is It Okay to Leave a Pool Drained?

Despite the risks, there are certain situations where draining and leaving a pool empty may be acceptable, particularly with the right precautions and timing.

Time of Year and Climate Considerations

In regions with cold winters, draining a pool partially or completely is often part of the winterization process to prevent freezing and pipe damage. In such cases, it’s only acceptable during the appropriate season and with proper winterizing steps taken to protect the structure and plumbing.

Preparing for Draining

To reduce risks when draining in winter prep:

• Backwash and clean the filter
• Drain water from pipes and pumps
• Use air plugs or expandable foam to prevent freezing damage
• Install a sturdy winter cover, not just a tarp

Short-Term Draining for Repairs

If you’re performing maintenance like tile cleaning, leak repair, or surface resurfacing, it may be necessary to drain the pool temporarily. In general:

• Drain only when absolutely necessary
• Leave it empty for no longer than a few days
• Take special care in areas where groundwater is a risk

For example, if you’re repairing a crack in a concrete pool, you’ll need it free of water to allow the repair products to cure effectively. However, it’s inadvisable to leave the pool completely drained for weeks under such circumstances.

Use of Hydrostatic Relief Valves

If your pool has a hydrostatic relief valve, this can help reduce pressure from groundwater in certain draining circumstances. Always consult a pool professional before draining, especially if you’re not certain whether your pool is equipped with these features.

Replacing or Removing Pools Permanently

If you are removing a pool or installing a new one, a full drain can be appropriate. However, it still requires care:
– Dismantle or seal off the area to ensure safety
– Inform local zoning or building inspection authorities
– Refill or properly cover the structure if removal is not completed

In such cases, leaving the pool empty may be okay temporarily, but always comply with local ordinances to avoid penalties or liability.

How to Safely Drain a Pool: Best Practices

When draining is necessary, approaching it the right way can make all the difference in protecting your investment and avoiding damage.

Check Local Regulations First

Before draining your pool, check with your city or county about discharge regulations. In many places, you cannot drain pool water into storm drains due to chlorine, salt, or chemical content that can harm local waterways.

Pool Water Disposal Options

• Dispose through household sewer clean-out
• Dechlorinate and discharge onto grass (if local codes permit)
• Contact professionals who specialize in pool water removal

Turn Off and Winterize Equipment

Never simply start draining without first shutting off and winterizing the equipment. This includes:

• Turn off the main power supply to the pool pump and heater
• Drain all lines and blow them out with an air compressor
• Use pool antifreeze in lines and filters to prevent freezing damage

Control Groundwater and Hydrostatic Pressure

If your region has high groundwater levels:

• Never fully or partially drain a pool in the spring, when water tables peak
• Monitor groundwater levels before making the decision to drain
• Use sandbags or temporary supports for fiberglass and vinyl pools

Many pool professionals advise that concrete pools must never be fully emptied without proper support.

Protect the Pool Surface

Once drained:

• Keep the surface clean and dry
• Use surface protectants or coverings to prevent UV degradation
• Store liner clips or tensioning devices for vinyl pools to avoid warping

If your pool is plastered, it’s a good idea to hose down the walls periodically to keep the surface hydrated during long-term draining in dry periods.

When to Seek Professional Help

Pool draining should not be a DIY task if you’re unsure of the risks or lack the proper tools. Here’s when you should call a professional:

If You’re Draining for the First Time

Not all pools can be safely drained. An expert can assess your pool type, groundwater levels, and structural needs before beginning the process.

If You Suspect Leaks or Structural Damage

Draining a leaky pool during high groundwater conditions can be dangerous and even costly. A certified pool technician can locate and fix leaks without fully draining the pool.

If You Live in an Area with a High Water Table

Professionals have the tools and knowledge to safely manage hydrostatic pressure and can advise on hydrostatic relief valves or temporary pump stations.

For Major Renovations or Resurfacing

Projects like retiling, replastering, or installing new equipment often require emptying portions of the pool. A qualified contractor can ensure the process is done correctly and safely.

Alternatives to Fully Draining a Pool

In many cases, you don’t need to completely empty the pool. Consider these alternatives:

Partially Draining the Pool

For maintenance like tile cleaning or waterline repair, draining just a portion can reduce structural stress. Use a submersible pump and wet vacuum to clean and repair without fully emptying.

Use Pool Repair Products That Work Underwater

Modern repair kits allow you to fix cracks, leaks, and tile issues without draining the pool. These are especially useful for temporary fixes until more extensive repairs can be made.

Seasonal Pool Covers and Maintenance Kits

Instead of draining your pool for winter, you can use a heavy-duty safety cover and maintain chemical balance with slow-dissolving tablets or flocculants. This keeps algae growth at bay and protects the surface without fully draining.

Conclusion: Is It OK to Leave a Pool Drained?

So, is it OK to leave a pool drained? The short answer is: sometimes, but with significant caveats.

If you’re dealing with cold climates and winterizing your pool, careful partial or complete draining is acceptable when done correctly. For short-term repairs, always assess the necessity and limit the time the pool is left empty. But for the average pool owner, especially with concrete or fiberglass structures, extended periods of draining can pose serious risks.

Ultimately, safety, structural integrity, environmental regulations, and proper maintenance are all critical factors to consider when deciding if leaving a pool drained is the right move.

Always consult with a licensed and experienced pool professional before draining your pool—your long-term enjoyment and the value of your property depend on it.

Final Checklist Before Draining Your Pool

1. Determine if draining is absolutely necessary
2. Consult local and environmental regulations
3. Check groundwater levels and structural risks
4. Winterize equipment safely
5. Plan for proper water disposal
6. Store or protect surface materials and equipment
7. Re-fill or winterize your pool before the season changes

Taking the time to make informed decisions and consult professionals can help ensure your pool remains in peak condition, whether it’s filled with water or temporarily empty.

Can leaving a pool drained cause structural damage?

Yes, leaving a pool drained for an extended period can lead to structural damage, especially in in-ground pools. Pools are designed to have water in them at all times, which helps balance the pressure between the water inside and the groundwater outside. When pools are emptied, especially in areas with a high water table, hydrostatic pressure from underground water can push the pool upward, causing it to crack, shift, or even “pop” out of the ground.

Additionally, the absence of water can cause tiles to loosen, plaster to dry and crack, and vinyl liners to shrink or warp. While short-term draining for maintenance or repairs is sometimes necessary, leaving a pool drained without proper precautions or oversight increases the risk of permanent damage that may require expensive repairs or even complete reconstruction.

Are there any benefits to draining a pool completely?

There are a few specific benefits to completely draining a pool, though they usually apply only in certain situations. For example, thorough cleaning, major repairs, or resurfacing projects often require full drainage to allow contractors to work effectively and safely. Draining can also reset chemical balance problems or help remove persistent algae buildup that can’t be cleared by partial draining methods.

In some cases, owners may also drain a pool to replace outdated components such as plumbing, tiles, or liners. However, these benefits come with risks, and full drainage should be done sparingly, with due consideration to weather conditions, groundwater levels, and the structural integrity of the pool shell. Consultation with a professional is often advisable before making the decision to fully drain any pool.

How long can you leave a pool drained without causing damage?

The amount of time you can safely leave a pool drained depends on the pool type, local environmental conditions, and the care taken during the draining process. In general, above-ground pools can be left drained for longer periods since they aren’t subjected to hydrostatic pressure from below. However, in-ground pools should not be drained for more than a few days — and even then, only under controlled conditions and when groundwater levels are low.

Even a short period without water can begin to affect the structural materials, especially during hot or dry weather, which can lead to plaster damage or cracking in concrete pools. To minimize the risk of damage, professionals usually recommend keeping the draining period as brief as possible and draining during seasons when the water table is at its lowest, such as late summer or early fall.

What precautions should you take if you need to drain your pool?

If you must drain your pool, it’s essential to take certain precautions to protect its structure and longevity. First, check groundwater levels by consulting a local pool professional or digging a small test hole nearby to assess if the water table is high. If it is, draining could be dangerous without hydrostatic relief valves or professional dewatering equipment. You should also clean the pool thoroughly before re-filling, ensuring that no debris or contaminants remain.

In addition, monitor the pool shell during the draining period and avoid extended exposure to direct sunlight or freezing temperatures. For in-ground pools, it’s wise to use bracing or water-filled weights if the draining period extends longer than expected. When refilling, do so as quickly as possible to evenly distribute pressure and avoid material distortion, and retest chemical levels before use to ensure water safety.

Can a pool be left partially drained safely?

Yes, it is generally much safer to leave a pool partially drained rather than completely empty. Partial draining can help perform certain maintenance tasks or chemical treatments without exposing the entire structure to the risks of being fully empty. Homeowners can keep enough water in the pool to maintain pressure balance and prevent liner shrinkage or plaster damage.

The ideal water level when partially draining typically depends on the type of pool. For pools with skimmers, water should stay above the skimmer opening to prevent damage. If performing routine tasks like cleaning or vacuuming, temporary lowering of the water level is acceptable. However, even partial draining should be monitored, especially if prolonged, to ensure environmental or temperature-related stress doesn’t cause any unintended damage to the pool structure.

Is it safe to drain a pool by myself, or should I consult a professional?

While small amounts of water can often be safely drained from a pool by homeowners using a pump, full drainage or prolonged draining should typically be left to professionals. Pool specialists can evaluate conditions such as the water table, local weather, and pool type to determine if draining is safe and what preventive measures are needed. Attempting this process without proper knowledge increases the risk of irreversible damage and costly repairs.

If structural work is involved, such as replacing tiles or repainting the interior, professionals have the necessary equipment and experience to maintain pressure balance and protect the pool during the process. They can also ensure the discharged water complies with local regulations, preventing environmental harm or fines. For homeowners unsure about the process or risks, hiring a licensed pool contractor is often the safest and most cost-effective choice.

What should I do after draining my pool to ensure it remains in good condition?

After draining a pool, the first step is to inspect the structure for any damage or wear that may have occurred during the drainage. Look for cracks, loose tiles, lifting, or warping in the liner or plaster, and make necessary repairs before refilling. Next, thoroughly clean the empty structure by brushing surfaces and rinsing away debris and sediment to create a fresh start for the refilling process.

When refilling, do so as quickly as possible to avoid exposure-related damage, and ensure the water level reaches the appropriate height for your pool’s design. Once filled, properly balance the chemicals and run the filtration system for several hours to circulate and purify the water. Allow the water to stabilize before swimming to ensure safety and longevity for continued use.