Closing your inground pool for the winter or for a long break is an essential task if you want to protect your pool and equipment. Many people think they need to drain all the water, but actually, closing an inground pool without draining water is safer, more efficient, and better for your pool. Draining can cause structural problems, ground pressure issues, and even cracks in the surface. If you close your pool properly—with the water still inside—you prevent damage, reduce costs, and save time for next season’s reopening.
This guide will walk you through every step to close your inground pool without draining the water. You’ll find practical tips, expert advice, and important warnings to help you avoid common mistakes. Whether this is your first time closing a pool or you want to improve your process, you’ll find everything you need here.
Why You Should Not Drain Your Inground Pool
Many pool owners are tempted to drain their pools to make winterizing easier, but this often leads to more problems than solutions. Here’s why keeping the water is the better choice:
Protects The Pool Structure
Your pool is designed to have water inside. The water pressure inside balances the ground pressure outside. If you remove the water, the outside soil can push against the empty shell, especially with concrete or fiberglass pools. This pressure can cause cracks or even make the pool pop out of the ground.
Prevents Drying And Cracking
Pool surfaces—like plaster or vinyl—can dry out and crack without water. The sun and cold temperatures damage the empty surface quickly. Cracks mean expensive repairs when you open the pool again.
Safer For The Environment
Draining a pool can send thousands of gallons of chemically-treated water into storm drains, harming local water systems. Keeping the water inside is a more environmentally-friendly way to close your pool.
Saves Money And Effort
If you close your pool with water inside, you avoid the cost and effort of refilling thousands of gallons in spring. Refilling also means balancing chemicals all over again, which is costly and time-consuming.
When To Close Your Inground Pool
Timing is important. If you close too early, you might get algae growth. If you close too late, freezing temperatures can damage equipment and pipes.
- In colder areas, close the pool when water temperature drops below 65°F (18°C). Algae stop growing below this temperature, and you’ll use fewer chemicals.
- In warmer climates, you may close later, but always before leaves and debris become a problem.
- Watch the weather forecast—never wait until the first hard freeze.
Essential Equipment And Chemicals
Before you start, gather everything you need. Missing a key item can make the process longer and less effective.
Equipment Checklist
- Pool cover (safety or winter type)
- Cover weights or water bags
- Pool skimmer and net
- Pool vacuum
- Pool brush
- Water testing kit
- Winterizing plugs (for return lines, skimmers, drains)
- Air compressor or shop vac (for blowing out lines)
- Pool antifreeze (non-toxic, for plumbing)
- Pump and filter system (for lowering water, if needed)
Chemicals Needed
- Chlorine shock or non-chlorine shock
- Algaecide (winter-specific is best)
- PH increaser/decreaser
- Alkalinity increaser
- Calcium hardness increaser
- Metal sequestrant (especially for well water)
- Stain and scale preventer
Step-by-step Guide To Closing Inground Pool Without Draining
Let’s break down the full process. Each step is important, and skipping or rushing one can cause problems later.
1. Clean The Pool Thoroughly
Before adding any chemicals or covering, the pool must be spotless. Debris left in the water can cause stains, promote algae, or clog your system.
- Skim the surface to remove leaves, bugs, and floating debris.
- Brush walls and floor to loosen dirt and algae.
- Vacuum the pool (manual or automatic) for a deep clean.
- Empty skimmer and pump baskets.
Pro tip: Don’t wait until the last day to clean. Leaves and dirt are easier to remove when they are fresh, not after sitting for days.
2. Test And Balance Water Chemistry
Balanced water is critical. If your water is not balanced, you risk corrosion, scaling, or algae over winter.
- PH: Aim for 7.4–7.6.
- Alkalinity: 80–120 ppm.
- Calcium hardness: 200–400 ppm.
- Chlorine: 1–3 ppm (but you’ll shock later).
Use a high-quality test kit, not just strips, for accurate results.
3. Shock The Pool
Shocking means adding a large dose of chlorine or non-chlorine oxidizer to kill bacteria, algae, and organic matter.
- Use 1–2 pounds of shock per 10,000 gallons of water.
- Run the pump overnight after shocking to distribute the chemicals.
- Wait until chlorine level drops below 3 ppm before adding winter algaecide.
Non-obvious insight: Always shock at dusk or night—sunlight breaks down chlorine quickly, reducing its effectiveness.
4. Add Winterizing Chemicals
After shocking and running the pump, add winter algaecide, metal sequestrant, and stain preventer. These protect your pool water and surfaces during the months ahead.
- Winter algaecide helps prevent algae growth even if chlorine drops.
- Metal sequestrant stops staining from metals in the water.
- Stain and scale preventer reduces calcium build-up and surface stains.
Follow label instructions for dosage based on your pool size.
5. Lower Water Level (but Don’t Drain)
You do not need to drain the pool—just lower the water level a bit.
- For mesh covers, lower water to 12–18 inches below the skimmer.
- For solid covers, lower water to 3–6 inches below the skimmer.
- Never drain all water—keep enough to cover the entire floor and most of the wall.
Important: Too much lowering increases risk of pool damage. Too little, and freeze expansion may overflow the pool.
6. Blow Out The Plumbing Lines
One of the most crucial steps is protecting your pipes and equipment from freezing. Water left in pipes can expand and crack them.
- Turn off the pump and filter.
- Use an air compressor or shop vac to blow air into the skimmer and through the return lines, pushing water out.
- When only air comes out, plug each line using winterizing plugs.
- Add non-toxic pool antifreeze to the lines for extra protection.
- Repeat for main drain (if possible), vacuum line, and any water features.
Common mistake: Forgetting to plug the lines tightly can let water seep back in, causing freeze damage.
7. Prepare The Filter And Pump
Each filter type has a special way to winterize. The goal is to remove water and protect from freezing.
Sand Filters
- Set the valve to “winterize.”
- Open the drain plug and let all water out.
- Remove the pressure gauge and store indoors.
Cartridge Filters
- Remove the cartridge; clean and dry it.
- Open the air relief and drain plugs to release water.
De Filters
- Backwash and clean the filter.
- Open all drain plugs.
- Remove grids and store indoors if possible.
Pump
- Remove all drain plugs.
- Tilt the pump to let out water.
- Store the pump basket indoors.
Pro tip: Store small parts like plugs and gauges in a labeled bag so you don’t lose them.
8. Remove And Store Pool Accessories
Take out ladders, handrails, diving boards, and any other removable accessories.
- Clean and dry all items.
- Store them in a dry, sheltered place to prevent rust or weather damage.
9. Install The Pool Cover
A strong cover keeps debris out and helps safety. The type of cover you use changes the installation.
- Safety covers anchor into the deck and keep children/pets safe.
- Winter covers use water bags or weights to hold in place.
Make sure the cover:
- Stretches tightly across the pool.
- Leaves no gaps for leaves or critters to enter.
- Is free from tears or holes.
Non-obvious insight: Check under the cover once or twice during winter for excessive water or debris. Early attention prevents headaches in spring.
10. Final Check And Maintenance Tips
Don’t just cover and forget. Even closed pools need a little attention through the cold months.
- Check the cover after storms for rips or heavy water.
- Remove standing water with a cover pump.
- Brush off snow to prevent cover collapse.
- If you see water level dropping under the cover, inspect for leaks (even in winter).
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Common Mistakes To Avoid
Even experienced pool owners sometimes make preventable errors. Here are the biggest pitfalls and how to avoid them:
- Skipping water testing before closing. Even if the pool “looks” clean, chemistry can be off.
- Not shocking enough or too close to closing—chlorine must circulate and drop to safe levels before adding other chemicals.
- Leaving water in lines—even a little can freeze and crack pipes.
- Improper cover installation—gaps or loose covers allow debris and small animals in.
- Forgetting to store accessories—they rust or get damaged if left outside.
- Not checking the pool mid-winter—small problems can grow if left until spring.
Comparing Pool Closing Methods
Some pool owners still debate whether to drain, partially drain, or close with water. Here’s a simple comparison to see why closing with water is best:
| Method | Cost | Pool Damage Risk | Winter Effort | Reopening Work |
|---|---|---|---|---|
| Draining All Water | High (refilling, repairs) | Very high (cracks, floating) | Medium | High (rebalance, refill) |
| Partial Drain | Medium | Some (if too low) | Medium | Medium |
| Closing With Water | Low | Very low | Low | Low (just adjust chemistry) |
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Essential Pool Chemicals: What They Do
Many beginners use too many or too few chemicals. Here’s a quick guide to the main types and their purpose:
| Chemical | Purpose | When to Add |
|---|---|---|
| Chlorine shock | Kills bacteria, algae | Before closing (night) |
| Algaecide | Prevents algae growth | After shocking, before cover |
| pH increaser/decreaser | Balances acidity | After testing, before shocking |
| Calcium increaser | Protects surfaces | If hardness is low, before closing |
| Metal sequestrant | Prevents stains | After shocking, before cover |
| Stain/scale preventer | Protects liner, tile | After shocking, before cover |
Safety Tips When Closing Your Pool
Closing your inground pool is not just about the water and pipes—safety is always important.
- Never close a pool alone—have someone nearby in case of emergency.
- Always use gloves when handling strong chemicals.
- Keep children and pets away from the pool area during closing.
- Secure all pool covers tightly to prevent accidents.
- Store chemicals in a locked, dry place, away from heat and children.
Troubleshooting Common Closing Problems
Even with careful planning, you might face issues. Here’s how to handle the most common ones:
Green Water When Closing
If your water is green, you likely have an algae problem. Shock heavily, brush, and run the filter until the water is clear before closing. Never cover a pool with algae—it will get worse.
Cloudy Water
Cloudy water usually means poor filtration, imbalance, or too much debris. Clean the filter, vacuum thoroughly, and balance chemicals. Wait for the water to clear before covering.
High Metal Content
If you have well water or old pipes, metals can build up and stain your pool. Add a metal sequestrant before closing to prevent brown or black stains.
Freezing Forecast Before Closing
If you’re surprised by an early freeze, turn off equipment, blow out lines, and add antifreeze as soon as possible. Temporary covers can help until you finish the process.
Opening Your Pool In Spring
The way you close your pool affects how easy it is to open again. Here’s what you can expect if you close the pool properly without draining:
- Water will be clearer and easier to balance.
- Less debris and staining.
- No structural damage from ground pressure.
- Less time and money spent on repairs.
Just reverse the steps: remove the cover, reconnect and prime equipment, balance water, and enjoy your pool sooner.
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Two Insights Most Beginners Miss
- Blowing out lines is more important than lowering water. Many new owners focus on water level but forget the pipes. Even a small amount of water in plumbing can cause expensive cracks. Always use an air compressor or shop vac to remove water from every line.
- Winter algaecide is not the same as summer algaecide. Winter formulas work slower but last longer. Using the wrong type means algae can still grow under the cover. Always choose products labeled for winter or long-term closing.
Where To Get More Help
If you’re unsure about any step, ask a local pool professional or check guides from trusted resources like the SwimmingPool.com website. They offer more details and safety tips.
Frequently Asked Questions
What Happens If I Drain My Inground Pool Before Closing?
Draining an inground pool can cause structural damage, cracks, or even make the pool shell rise out of the ground. Most manufacturers and experts advise against it unless you need major repairs.
Can I Use The Same Chemicals For Closing As During The Swimming Season?
Some are the same (like shock), but winter algaecides and stain preventers are made for long-term use. Always check the product label for the best results.
How Often Should I Check My Pool After Closing?
Check your pool cover every 2–4 weeks for water, debris, or damage. After heavy storms, check as soon as possible. Early attention prevents bigger problems.
Do I Need To Run My Pool Pump During Winter?
No, once you close and winterize your pool, you should turn off and disconnect your pump. This prevents freezing and saves energy.
What If I Forget To Blow Out One Of The Lines?
If water stays in the pipes, it can freeze, expand, and crack the plumbing. If you think you missed a line, try to blow it out again or add extra pool antifreeze for protection.
Closing your inground pool without draining the water is the safest and most effective way to protect your investment. With careful planning and attention to detail, you’ll avoid costly damage and enjoy a smoother opening next season. Take the time now, and your pool will thank you all year long.