Managing your pool during the winter months is just as crucial as maintaining it during the swimming season. While you may not be diving into the water when temperatures drop, proper winter pool care is necessary to protect your investment and ensure your pool is in good condition when warmer weather returns. One of the biggest questions pool owners face each year is: What do you do with pool water in the winter? The answer depends on several factors, including your climate, the type of pool you own, and your long-term goals for water conservation and maintenance.
This guide will walk you through the best practices for handling pool water in winter, including draining, covering, chemical balancing, winterizing equipment, and more.
The Importance of Winter Pool Maintenance
Properly preparing your pool for winter is essential. Failure to do so can lead to costly damage from freezing temperatures, algae growth, and equipment failure. While the specific steps you take will vary depending on your location, understanding how to care for your pool water is key to long-term pool health.
Regional Considerations
In regions where winter temperatures regularly fall below freezing, pool owners must winterize their pools by draining or partially draining the water and protecting pipes and pumps from ice damage. In milder climates, where freezing is less common, you might only need to cover the pool and maintain basic chemical balance.
Check Local Guidelines
Before proceeding with any winter pool care, always check local plumbing and environmental codes. Some areas have restrictions on how much water you can drain due to water conservation laws or municipal regulations.
Should You Drain Your Pool for Winter?
The question of whether to drain your pool for winter is one of the most common—and potentially most damaging—if not done correctly. In most cases, you should not completely drain your pool unless you have a specific reason to do so, such as undergoing major repairs or re-plastering the pool surface.
Partial Drain vs. Full Drain
For most in-ground pools, it’s recommended to lower the water level slightly—typically below the skimmer—and leave enough water to protect the pool structure. Saltwater pools, in particular, often require water to remain in the pool to protect the salt cell and other components. For above-ground pools, partial draining is often not sufficient; in colder climates, full draining may be necessary.
Risks of Draining a Pool Completely
- Structural damage: Pools can rise above ground due to hydrostatic pressure from groundwater.
- Equipment damage: If water is left in lines or equipment, freezing can cause cracks.
- Stain development: Drained pools may accumulate dirt or stains if not cleaned thoroughly.
| Pool Type | Recommended Draining Level | Winterization Tips |
|---|---|---|
| In-ground Concrete | 6–12 inches below skimmer | Use airbags or leave water at a safe level |
| Vinyl Liner In-ground | Just below the skimmer | Use a winter cover and air pillow |
| Above-ground | Completely drain | Disassemble and store pump and filter |
Winterizing Your Pool Water
Once you’ve decided how much water to leave in your pool, the next step is to winterize it properly to protect against algae, bacteria, and freezing damage.
1. Balance the Water Chemistry
Before winter sets in, it’s essential to balance your pool’s chemical levels to inhibit algae growth and corrosion. The key parameters to test and adjust are:
- pH (Ideal range: 7.2–7.6)
- Alkalinity (70–80 ppm)
- Chlorine (1–3 ppm)
- Calcium Hardness (200–400 ppm for plaster pools, 150–250 ppm for vinyl pools)
2. Add a Winterizing Chemical Kit
Most pool stores sell pre-assembled winter chemical kits, which typically include:
- Algaecide to prevent winter algae growth
- Chlorine shock to eliminate organic contaminants
- Enzymes to break down oils and other organic substances
Adding these chemicals ensures the water remains clean and balanced while the pool is unused.
3. Use a Pool Cover
A proper pool cover is one of the most effective tools for winter pool care. Whether your pool is in-ground or above-ground, investing in a high-quality winter cover is essential to prevent debris from entering the water, reduce evaporation, and keep sunlight from encouraging algae growth.
There are several types of pool covers:
| Cover Type | Best For | Pros | Cons |
|---|---|---|---|
| Solid Vinyl Cover | Winterizing in cold climates | Blocks sunlight, keeps debris out | Requires a pump or cover reel |
| Mesh Safety Cover | Heavy-duty use and safety | Drains water, durable for snow | May allow sunlight through |
| Thermal Blanket | Moderate climates | Insulates water, saves chemicals | Not durable for heavy winter use |
Protecting Pool Equipment During Winter
Winter pool care doesn’t stop with the water. Your pool equipment—including pumps, filters, heaters, and automatic cleaners—must also be winterized to prevent damage.
Winterizing Your Pool Pump and Filter
To prevent water from freezing inside the equipment:
- Turn off the circuit breaker.
- Drain water from the pump, filter, and heater using drain plugs.
- Remove drain plugs and valves to allow air circulation.
- Store any removable parts indoors, especially in areas of heavy freeze.
Using a shop vacuum or air compressor to blow out lines is a common practice in colder climates.
Caring for Saltwater Pools
Saltwater pool systems require special attention. After shutting down the system:
- Drain the saltwater chlorine generator cell completely.
- Rinse the cell with fresh water and store it indoors.
- Test the salt level and adjust it before winter to avoid corrosion during inactivity.
Managing Pool Water Temperature
Even when the pool is not in use, managing its temperature can affect its condition over winter. In areas with extremely cold temperatures, lowering the water level and insulating the water surface can help prevent ice-related damage.
Insulation Options
Consider floating pool pillows or airbags in the pool. This helps absorb pressure if ice forms on the surface and prevents it from pushing directly against the pool walls.
How to Use Air Pillows
- Place them in the deepest end of the pool.
- Secure them with cords or let them float freely.
- Cover the pool after positioning the pillows.
This is particularly important for vinyl liners, which are more susceptible to damage from ice expansion.
Should You Keep the Pool Heater On in Winter?
In most cases, the answer is no. Pool heaters should be shut down and winterized. If you live in a mild climate and are only closing the pool temporarily, you may consider keeping it at a lower setting. However, for long-term pool closure during cold winters, draining and covering the pool is more effective and energy-efficient.
Heater Winterization Steps
- Turn off the gas line and electricity.
- Drain water from the heater and associated lines.
- Wrap the unit to prevent moisture or debris from entering.
- Remove any electronic components and store indoors.
What About Pool Water Conservation?
In areas facing water shortages or drought conditions, it’s important to consider conservation strategies even in the winter swimming pool closure process. Drainage should be minimized whenever possible.
Alternatives to Draining Pool Water
Instead of fully draining your pool, consider:
- Using a pool cover to reduce evaporation and contamination.
- Recirculating or using the water in landscaping (if safe).
- Donating or transferring pool water to another pool or use in irrigation if local regulations allow.
Additional Winter Pool Tips
- Check the pool cover regularly for standing water and debris.
- Use a pool cover pump to remove rain or snowmelt that accumulates on solid covers.
- Keep the pool’s filtration system clean before shutting down for winter.
- Label all pool equipment and valves for easy startup in spring.
- Record chemical levels, equipment settings, and any specific notes to help you reopen next season.
Conclusion: Smart Winter Pool Water Practices
Knowing what to do with pool water in the winter is essential for maintaining the integrity of your pool and equipment. Whether you live in a cold climate that requires full winterization or a mild area where simple coverings and chemical adjustments suffice, the proper care of your pool during the off-season will extend its lifespan and save you time and money in the long run.
From balancing water chemistry and using effective covers, to properly winterizing equipment and making decisions on drainage, each of these steps contributes to safe and effective winter pool management. Always remember to tailor your winter pool care strategy to your local climate and follow manufacturer recommendations for all pool equipment. By doing so, you ensure your pool will be ready for another season of enjoyment once spring returns.
Should I drain my pool for the winter?
Draining a pool for the winter is generally not recommended unless necessary for repairs or maintenance. Completely draining a pool can lead to structural damage due to ground water pressure, which may cause the pool to shift or even pop out of the ground. For most in-ground pools, the proper method is to lower the water level slightly—below the skimmer but not entirely—to protect against freezing and expansion damage while maintaining the structural integrity of the pool.
Above-ground pools may require different handling, sometimes necessitating full draining depending on the model and climate. If you live in an area with harsh winters and freezing temperatures, it’s crucial to follow manufacturer guidelines for your specific pool type. In many cases, a partial drain combined with winterizing chemicals and a secure cover is the ideal way to protect your pool without risking damage from being completely empty.
How do I winterize my pool water?
Winterizing pool water begins with thoroughly cleaning the pool, including brushing the walls and vacuuming debris from the floor. Next, balance the water chemistry by testing and adjusting the pH, alkalinity, calcium hardness, and chlorine levels. Proper chemical balance prevents corrosion, staining, and algae growth during the off-season. After balancing the water, add a winterizing algaecide and a shock treatment to ensure the water remains clear and bacteria-free throughout the winter months.
Once the chemicals are added, lower the water level appropriately (usually below the skimmer) and drain water from the plumbing lines using a blower or compressor. It’s important to add a winter pool cover securely to prevent debris and animals from entering the water. In areas with freezing temperatures, using a floating pool cover or inserting an air pillow under the cover can help absorb ice expansion and reduce stress on the pool structure.
Can I use a tarp as a winter pool cover?
While tarps can be used in emergencies, they are not an ideal replacement for a proper winter pool cover. Tarps are often not designed to handle the specific demands of pool winterization, such as UV resistance, durability against snow and ice, and proper water drainage. Using a tarp may lead to sagging, tearing, or allowing debris and moisture to enter the pool, which could result in cleaning issues and potential damage to the pool surface.
Instead, invest in a specially designed winter cover that fits your pool’s dimensions. Solid covers are great for keeping debris out, while mesh covers allow water to pass through, reducing the risk of standing water accumulation. These covers are typically reinforced and come with grommets for secure attachment with water bags or anchors. The right winter cover is a crucial component of a successful pool winterization process.
What chemicals do I need for winterizing my pool?
To properly winterize your pool, you’ll need a few key chemicals: a pool shock, algaecide, and a water balancing kit. Begin by testing your water to adjust pH, alkalinity, and calcium hardness before winter arrives. This step helps prevent corrosion or scaling during the months when the pool isn’t actively being maintained. Once the water is balanced, a shock treatment using a chlorine-based or non-chlorine shock will eliminate bacteria and organic contaminants.
After shocking the pool, add a high-quality winter algaecide to inhibit algae growth during the colder months. Some winterizing kits include all the necessary chemicals in one package, making the process more efficient. It’s also wise to add stain and scale inhibitors to protect the pool surfaces from discoloration due to mineral buildup. These chemicals should be evenly distributed around the pool before covering it for the season.
How often should I check the pool during winter?
Even though your pool is covered during winter, it’s still beneficial to check it periodically, ideally every few weeks when conditions allow. Regular checks ensure the cover remains secure and intact, preventing debris, leaves, and excess water from accumulating on the pool surface. You should also look for signs of shifting, tearing, or sagging, which could lead to water accumulation and potential damage to the pool’s structure or cover system.
If your climate experiences heavy snowfall or rain, you may need to pump excess water off a solid cover to prevent undue stress. For mesh covers, it’s essential to ensure proper drainage through the cover and that the pool water level is stable. Monitoring the pool’s condition throughout the winter season can help you avoid costly repairs and minimize cleaning efforts when it’s time to reopen the pool in spring.
Do I need to run the pool pump during winter?
Once the pool is properly winterized and covered, there’s typically no need to run the pool pump throughout the entire winter. However, it’s a good idea to run the pump for a few hours during the initial winterization process to circulate the added chemicals. After that, unless you live in a milder climate where freezing is not a concern, you can shut off and store your pool equipment properly.
In some areas, it’s beneficial to occasionally run the pump during winter thaws to maintain water circulation and prevent stagnation under the cover. If you do decide to run the pump intermittently, ensure the temperature is above freezing and that water will not freeze in the plumbing lines. Otherwise, it’s best to leave the system off after winterization. Remember to keep the electrical components protected to avoid moisture-related damage during the off-season.
What steps should I take to reopen the pool in spring?
To reopen your pool in spring, start by removing the winter cover carefully, using a pool cover pump to eliminate any standing water on top. Clean the cover before storing it to extend its lifespan and prevent mold growth. Next, begin refilling the pool to its normal operating level, as some water loss is typical during winter due to evaporation and precipitation.
Inspect the skimmer, pump, and filter for any signs of debris or wear, and clean them before starting up the system. Reconnect the plumbing lines and backwash the filter to help restart circulation. Test the water chemistry and balance the pH, alkalinity, calcium hardness, and sanitizer levels. Shock the pool after the first few days of circulation and add algaecide to address any early signs of algae. Once the water is clear and balanced, you’re ready for another swimming season.