Maintaining a clean, safe, and attractive inground pool requires regular attention to many aspects of pool upkeep. One of the most critical—and often debated—maintenance tasks is draining the pool. Whether you’re a new pool owner or have been managing your pool for years, understanding when and how often to drain an inground pool is essential for preserving water quality, chemical balance, and the integrity of the pool structure.
This comprehensive guide explores the various reasons you may need to drain an inground pool, the factors that determine how often to do so, and the practical steps to follow. We’ll also provide tips on how to avoid unnecessary draining and what environmental and local regulations may apply.
Why You Need to Drain Your Inground Pool
There are several situations that may require pool drainage, but not all are equally urgent. Here are the main reasons why draining your pool is necessary:
Excessive Chemical Build-Up
Over time, chemicals such as chlorine, calcium, and cyanuric acid (CYA) accumulate in your pool water. This build-up can cause:
- Cloudy or discolored water
- Eye or skin irritation for swimmers
- Reduced effectiveness of chlorine
In such cases, partial or full draining may be the only solution to restore proper chemical balance.
High Total Dissolved Solids (TDS)
As the name suggests, TDS refers to the sum of all dissolved materials in the water. High TDS levels can make water feel salty or cause scaling. The ideal TDS level is between 0–1,500 ppm. If it exceeds 2,500 ppm, draining becomes necessary.
Maintenance or Repairs
Draining the pool is essential if:
- Interior resurfacing or plaster repairs are needed
- There are issues with the plumbing system
- If you need to winterize the pool
These maintenance tasks often require the water level to be significantly lowered or completely emptied.
Severe Contamination or Algae Bloom
Though rare, severe algae overgrowth or contamination (e.g., after a storm, flooding, or a sewage leak) can overwhelm the filtration system and sanitizers. In these situations, draining the pool might be the most effective and safe course of action.
How Often Should You Drain an Inground Pool?
As a general rule of thumb, most pool experts recommend draining and refilling an inground pool every three to five years. However, this is not a one-size-fits-all rule due to varying factors such as:
Pool Type and Material
Different types of inground pools have different maintenance needs:
| Pool Type | Recommended Drain Frequency |
|---|---|
| Concrete (Gunite) | Every 5–7 years |
| Vinyl Liner | Every 3–5 years |
| Fiberglass | Every 5–10 years |
Concrete pools are more robust and can go longer without draining. However, they are more vulnerable to mineral build-up due to their porous surface. Vinyl pools, on the other hand, are prone to staining and wear, so they may require more frequent attention.
Usage Intensity
Pools used daily, especially in households with many swimmers or in commercial settings, need more frequent draining. High swimmer load leads to faster chemical and contaminant build-up, increasing the burden on your filtration system and chemical regimen.
Local Water Quality
The quality of the water supply can also influence drainage frequency. Hard water, rich in calcium and minerals, accelerates scaling and necessitates more frequent draining. Soft water, though less likely to contribute to scaling, can increase the likelihood of etching in concrete pools if not monitored.
Chemical Maintenance Practices
Proper chemical maintenance can prolong the time between drainings. Conversely, inconsistent practices or heavy reliance on certain chemicals (like those based on stabilizers) may shorten intervals between full drains.
Environmental Factors
If your pool is in an area with high pollen, dust, leaves, or rainfall, you’ll likely need to manage your water more frequently. Outdoor pools are also exposed to sun-evaporation cycles, which can lead to TDS increases and higher chemical demand.
Signs That Your Pool Needs Draining
Knowing when to drain your pool can save you from costly damage and health hazards. Here are some key indicators to look for:
Water Test Results
Use a professional test kit or take a sample to your local pool store to check the following levels:
- Cyanuric acid (CYA) — Levels above 100 ppm reduce chlorine efficiency.
- TDS — Exceeding 2,500 ppm means water is too saturated.
- Calcium hardness — Above 400 ppm can lead to scaling.
- pH levels — Consistently unbalanced.
These readings can determine whether partial or full draining is required.
Visual and Sensory Indicators
Be alert for signs that can be seen or felt:
- Cloudy, foamy, or oily water that persists despite filtering and chemical treatment
- Stains on walls and floor that won’t respond to brushing or stain remover
- Chalky residue when touching pool surfaces (scaling)
- Unpleasant odor or irritation to eyes/skin
These issues tend to signal that chemical balances are beyond repair through normal pool maintenance and draining is necessary.
Impact on Water Feel
If the water feels different—bitter, slimy, or salty—it could indicate high TDS or chemical imbalances. These are subtle yet important cues from your pool to take action.
Types of Pool Draining Scenarios
Understanding the different draining levels can help determine the appropriate course of action:
Partial Drain
A partial drain involves removing only a portion of the water, typically through the main drain or using a submersible pump. This is often sufficient when:
- High CYA levels are detected
- Minor staining or scaling is developing
- Preparing pool for shock treatment
You can also lower the pool water level to below the skimmer line during winterization to prevent freezing damage.
Complete Drain
Full draining removes all water from the pool. This is generally the only solution if:
- Major plaster issues or resurfacing are required
- Severe contamination has occurred
- Algae is out of control and chemicals are ineffective
- Major structural repairs are being done
However, full draining can be costly and time-consuming, and may expose the pool to potential damage if not done properly.
Can You Safely Leave Your Pool Empty?
Never leave your empty pool unattended for too long. For concrete pools, extended periods of emptiness without water can result in:
- Rising groundwater pressure cracking or lifting the shell
- Drying and shrinking of plaster surfaces
- Structural weakening due to ground movement
Vinyl and fiberglass pools also risk damage from heat distortion or collapse if left empty improperly.
How to Properly Drain an Inground Pool
If you’ve determined it’s time to drain your pool, follow these essential steps to protect your pool structure and surrounding property:
1. Check Local Water Regulations
Before you begin, verify local laws on pool water discharge. Some areas prohibit draining into storm drains, gutters, or local waterways due to chemical levels or environmental impact. There may also be restrictions during drought conditions or water conservation periods.
2. Choose the Right Drainage Method
There are several effective methods for draining a pool:
- Using a submersible pump—Ideal for partial or full draining and offers better control.
- Dedicated drain plug—Some pools come with a drainage system designed to empty via underground lines.
- Garden hose siphon method—A slow but inexpensive option for small water reductions.
Always ensure proper hose placement to avoid water reentry or nearby damage.
3. Monitor Water Level During Draining
For concrete pools, in areas with high water tables, it’s advised to not empty the pool completely unless necessary. Draining more than 1/3 of the depth without backfilling or anti-floating measures can be dangerous.
Degree of Draining and When:
| Degree of Drain | Use Case | Time Required |
|---|---|---|
| 40–60% drain | Adjust chemical imbalance or prepare for shock treatment | 1–2 days |
| Full drain | Resurfacing, liner replacement, or repair | 3+ days |
4. Proper Disposal of Drain Water
Pool water typically contains chlorine or salt and should be dechlorinated before release unless permitted otherwise. Use a dechlorination kit or sodium thiosulfate to safely neutralize chlorine levels before discharging the water.
Discharge water into:
- Sanitary sewer systems (with permission)
- Permitted drainage areas
- Non-sensitive ground zones (avoid waterways or wildlife habitats)
5. Protect the Pool During and After Draining
If partially drained, ensure your pump and filtration system are not running dry, which can damage equipment. If fully drained, follow these best practices:
- Keep it filled temporarily with groundwater relief systems if required.
- Secure the pool area to prevent accidents or debris build-up.
- Keep the pool bottom wet if left empty for a few days to control dust.
Alternatives to Frequent Pool Draining
Draining a pool can be time-consuming, expensive, and environmentally wasteful. Fortunately, there are several preventive and alternative maintenance strategies to extend the time between full drainings.
Proper Water Chemistry Management
Maintaining a balanced chemical regime is the most important step toward pool water longevity. Monitor:
| Parameter | Recommended Range | Solutions to Maintain |
|---|---|---|
| Free Chlorine | 1–3 ppm | Regular testing, shock treatments |
| pH | 7.4–7.6 | pH increasers/decreasers |
| Alkalinity | 80–120 ppm | Alkalinity adjusters |
| Calcium Hardness | 200–400 ppm | Hardness reducers or calcium additives |
Regular testing can help you avoid letting minor problems become big enough to require draining.
Use a Saltwater Chlorination System
Saltwater pools are not chlorine-free but generate chlorine from salt. These systems regulate chlorine levels more consistently and reduce the accumulation of stabilizers like CYA, which can decrease the need for draining.
Install a Reverse Osmosis (RO) Water Treatment System
Advanced filtration systems, such as RO units, can effectively remove dissolved solids without draining your pool, extending the life of your water and reducing water waste.
Encourage Shower Before Swimming
Minimizing the introduction of body oils, lotions, and dirt reduces contaminant levels that contribute to chemical demand and discoloration.
Use a Pool Cover
While primarily used for heat retention and debris control in colder climates, pool covers limit evaporation and reduce the need for make-up water, helping maintain chemical concentrations.
Environmental Considerations and Water Conservation
With climate change concerns and growing water scarcity, pool owners are under pressure to conserve resources. Proper water management, including delaying unnecessary draining and using partial draining where possible, has a direct positive impact.
Water Reuse and Treatment
Some innovative pool owners use treated stormwater or greywater systems for top-off in hot conditions. In certain areas, you may even be able to use filtered backwash water for irrigation (if dechlorinated).
Community and State Guidelines
Check with your local water authority or environmental protection office for rebates or regulations related to pool draining. Some regions, like drought-prone California, have strict guidelines or offer incentives for alternative treatments and water recycling.
Professional Pool Services
Hiring a professional pool service can ensure optimal maintenance and timely detection of imbalances. A skilled technician will know when to drain your pool based on readings and the condition of your water and structure, often saving you from premature or unnecessary complete drainings.
Conclusion: A Balanced Approach to Pool Drainage
Draining an inground pool is a necessary but not routine procedure. Understanding the factors that influence how often to drain your pool can help you make informed decisions about pool maintenance. Whether your pool needs draining every three years or closer to seven depends on your usage, local climate, water supply, and overall maintenance habits.
By proactively managing water chemistry, using advanced systems like RO treatments and saltwater chlorination, and following local water conservation guidelines, you can prolong draining intervals while maintaining a clean, enjoyable, and safe swimming environment.
Always assess your specific pool type, water quality, and local regulations before deciding to drain. A well-maintained pool not only offers more fun but also lasts longer, reduces repair costs, and minimizes your environmental footprint.
How often should you drain an inground pool?
Draining an inground pool is not something that needs to be done frequently. On average, it’s recommended to completely drain and refill your pool every 5 to 7 years. However, this can vary based on factors like water quality, local evaporation rates, and chemical usage. If the water becomes heavily contaminated or if maintenance has been neglected, you may need to drain the pool sooner.
Regular maintenance such as balancing pH levels, using the right pool chemicals, and cleaning the filter can help extend the interval between full drainings. Partial water replacement, which involves removing a portion of the pool water and refilling it, can also help manage mineral and chemical buildup. Ultimately, periodic testing of water chemistry and close observation of the pool’s condition should help guide decisions about draining.
What are the risks of not draining an inground pool regularly?
If a pool isn’t drained on a regular basis, the water can become saturated with chemicals, minerals, and contaminants that are difficult to manage through regular maintenance alone. Over time, this can lead to scaling on pool surfaces, cloudy water, and malfunction of filtration systems. In turn, this makes the pool harder to clean and can affect the efficacy of sanitizers like chlorine.
Additionally, high total dissolved solids (TDS) can cause discomfort for swimmers, such as skin irritation and eye redness. Continued use of highly saturated water can also damage the pool’s equipment and reduce its lifespan. In extreme cases, especially in areas with high evaporation, stagnant or overly concentrated water can lead to etching or spotting on plaster surfaces.
Do I need to drain my pool before winter?
Draining your pool completely before winter is not typically necessary for most inground pools. Instead, most experts recommend partially lowering the water level below the skimmer and returning jets to accommodate for expansion if freezing occurs. Completely draining the pool in winter can actually be harmful, as water in the ground can push the empty pool upward, causing structural damage.
Proper winterization involves balancing the pool water, adding winterizing chemicals, cleaning the pool thoroughly, and installing a winter cover. This protects the pool from debris and ice damage. Each pool is different depending on location and climate, so always follow the winterization guidelines specific to your type of pool and local weather conditions.
Can evaporation cause a pool to need draining?
Yes, in regions with high evaporation and limited or no rainfall, pool water can lose significant volume over time. As water evaporates, the chemicals and minerals in the pool remain behind, leading to increased concentrations that can negatively impact pool health. When these levels become too high, it becomes necessary to drain part or all of the pool to reset the chemical balance.
To avoid issues from evaporation, regular testing and adjustment of water chemistry is essential. Adding fresh water periodically can help, but in areas where evaporation is severe, draining and refilling may be the only practical solution. Monitoring local weather patterns and compensating accordingly will help you maintain clean, safe water without unnecessary drainings.
How do high chemical levels influence the need to drain an inground pool?
High chemical levels, especially when total dissolved solids (TDS) are elevated, can interfere with the performance of sanitizers like chlorine. This reduces the effectiveness of water treatment and can result in persistent algae growth and cloudy water. The only effective way to correct this, once TDS or chemical concentrations pass acceptable levels, is to drain a portion or all of the pool and replace it with fresh water.
Typical indicators that chemical levels are too high include scaling on pool surfaces, irritation to swimmers’ eyes and skin, and more difficulty maintaining sanitizer effectiveness. Testing water regularly—using either a home kit or professional service—helps you track chemical levels. When these become unsalvageable through other chemical adjustments, it’s time to consider partial or full draining.
Can partial draining of an inground pool help extend the time between full drainings?
Yes, partial draining is a helpful way to manage water chemistry and extend the time between full drainings. By replacing a portion of the pool water, typically 20-50% depending on chemical levels, you can dilute concentrations of minerals, chlorine byproducts, and other dissolved solids. This not only improves clarity and comfort but also helps keep equipment running efficiently.
To perform partial draining correctly, be sure not to lower the water level below the skimmer unless your filtration system is turned off and winterized. Use a submersible pump for precise draining and refill using a garden hose with a water source that meets pool-grade quality. Monitoring your chemical balance before and after partial draining will help you decide whether a full drain remains necessary.
Is it safe to drain an inground pool on my own?
Draining a pool is a task that requires preparation, the right equipment, and careful monitoring. While some pool owners choose to do it themselves, mistakes like draining too quickly or not preparing the structure properly can lead to significant damage, including shifting or floating the pool due to ground pressure. It’s important to follow the manufacturer’s recommendations and consult a professional if conditions are uncertain or extreme.
If you’re planning to DIY, ensure proper drainage of water away from the pool and into suitable outlets to avoid flooding your yard or neighboring areas. You must also check local regulations, as some cities restrict or regulate how pool water is disposed of. Always turn off the pump and other systems as required, and if you’re not confident in your understanding of the process, it’s better to hire a professional to avoid accidents or costly repairs.