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During winter, pools should be drained below the skimmer to prevent damage from freezing. The skimmer is usually the highest point of most in-ground pools, so draining below this level exposes the walls and floor to freezing temperatures. Draining to this level reduces the weight of the remaining water, preventing cracks and pops from ice expansion. The pump, filter, and other pool equipment should also be properly winterized before draining.
Should You Drain Your Pool Below the Skimmer for Winter?
When winterizing an in-ground pool, most experts recommend draining the water level below the skimmer opening. This is done to prevent freeze damage as temperatures drop below freezing. Here are some key reasons why draining below the skimmer is recommended:
Prevents Ice Damage to Pool Surface
The skimmer opening is usually the highest point on the pool walls. By draining below this level, you expose more of the pool surface to the air. This allows the remaining water to expand as it freezes without putting excess pressure on the pool shell. If you leave the water level high, the ice has nowhere to expand and can crack or pop the plaster. Draining below the skimmer gives the ice room to expand safely.
Reduces Weight and Pressure
When water freezes, it expands in volume by almost 10%. This expansion puts tremendous pressure on the pool shell and structure. By draining away most of the water, you reduce the overall weight and pressure on the pool walls and floor. The less water remaining, the less potential for damage from ice expansion.
Prevents Skimmer Damage
The skimmer itself can also crack and break if water is left in this top portion of the pool. As water in the skimmer freezez, it expands forcefully. This can easily damage the skimmer housing and components. Draining below this level keeps these expensive parts safe from freezing issues.
Allows For Proper Winterizing
Draining below the skimmer line gives you full access to winterize the skimmer, plumbing, and pump/filter system. The return jets, drain plug, pump basket, and filter should all be fully drained and dried out. Lowering the water to the skimmer opening allows you to properly winterize all associated pool equipment and plumbing.
How Low Should You Drain the Pool?
Most pools should be drained to at least 6-12 inches below the skimmer opening. Here are some guidelines on how far down to drain for winter:
- Fiberglass pools – Drain to just below the skimmer
- Vinyl liner pools – Drain to midway on wall
- Gunite pools – Drain 12-18 inches below skimmer
Fiberglass pools require less draining since they are more flexible than other surfaces. Vinyl liner pools can safely be drained to about mid-way down the wall. For concrete or gunite pools, draining even lower down to 18 inches is recommended.
Mark Water Level
Use a grease pencil or tape to mark the water level after draining. This helps you refill to the same level in spring. Avoid draining too low, as completely drying out the pool surface can cause plaster cracking or damage.
Cover Pool Immediately
After draining, the pool should be immediately covered with a safety pool cover. This prevents rain from filling it back up and keeps out leaves and debris over winter.
Steps to Drain a Pool for Winter
Draining an in-ground pool properly for winter involves a specific sequence of steps:
- Test and balance chemicals – Get water chemistry balanced before draining.
- Clean pool surfaces – Remove algae and debris before draining.
- Shut off electricity – Turn off power to pump and other equipment.
- Remove plugs – Remove skimmer and return jet plugs.
- Attach hose – Connect pump outlet hose to direct water away from pool.
- Open drain valve – Open valve at bottom main drain if available.
- Start pump – Turn on pump to start draining water.
- Winterize equipment – Drain and protect pump, filter, pipes, etc.
- Lower water level – Run pump until water is lowered properly.
- Mark level – Mark lowered water level for spring reference.
- Install cover – Cover pool immediately after draining.
This systematic process allows for complete drainage and winterizing of the entire pool system. Rushing through or skipping steps can lead to damage.
Avoid Pumping Off Too Much Water
While it’s important to lower the level sufficiently, pumping off too much water is problematic. If the water level drops too far, the hydrostatic valve under the pool can be damaged. This important valve prevents groundwater from lifting the pool out of the ground. Avoid draining off more than 18 inches below the skimmer.
Closing Tips for Pool Skimmers
The skimmer itself also needs to be properly winterized when closing a pool. Follow these tips for skimmer preparation:
- Drain and dry skimmer housing – Remove all water from the skimmer body using a wet/dry shop vac.
- Remove basket – Take out skimmer basket and store dry over winter.
- Seal openings – Plug skimmer opening and pipe with a gizmo or winter plate.
- Disconnect hoses – Detach filter hoses from the skimmer housing.
- Cover skimmer – Drape skimmer opening with plastic or canvas for winter.
Ensuring no moisture is left in the skimmer body prevents freezing and cracking over winter. Cover plates and plugs keep out snow, debris, and animals.
Winter Considerations by Pool Type
Draining requirements also depend on the specific pool type and material:
Concrete/Gunite Pools
- Drain to 12-18 inches below skimmer
- Steel wall pools drain to just below skimmer
- Mark water level before covering
- Cover with mesh safety cover
Vinyl Liner Pools
- Drain to midway down pool wall
- Loosen liner from wall as water lowers
- Do not drain completely empty
- Cover with water tubes or mesh cover
Fiberglass Pools
- Only need to drain below skimmer opening
- These flex more than other surfaces
- Immediately cover entire pool
- Consider floating pool cover
Understanding the structural differences of each pool type ensures proper winterizing for your specific pool surface and construction.
Prepping Pool Equipment for Winter
In addition to the pool itself, all related plumbing and equipment must be properly winterized each fall. Here are key steps to take:
Pump and Filter
- Completely drain pump basket and filter
- Disconnect hoses and pipes
- Remove and store filter cartridge or DE grid
- Cover pump motor to protect from moisture
- Consider installing freeze plugs
Heater and Plumbing
- Drain water from heater using flush plugs
- Disconnect heater from pump and plumbing
- Seal off return jets and other plumbing openings
- Blow out all pool pipes using air compressor
Automation System
- Disconnect all electrical connections
- Remove main controller from poolside
- Store sensors and other hardware safely
- Turn off circuit breakers for equipment
Completely removing water from all equipment prevents freeze damage. Disconnecting parts makes spring start-up and reassembly easier as well.
What Else Should be Done When Closing a Pool?
Along with proper draining and winterizing steps, a few other tasks should be completed when shutting down your pool:
- Clean and scrub all pool surfaces
- Balance chemicals and add algaecide
- Remove loose items and debris from the pool
- Turn off electricity to pool equipment
- Shut off gas supplies to heater and other appliances
- Lubricate o-rings and gaskets
- Cover pool with mesh safety cover
- Consider a water bag for added pressure
Addressing these aspects ensures the pool is protected from chemical imbalance, debris, and standing water over the winter months.
Is it Bad to Leave Pool Full Over Winter?
Leaving the pool completely full over winter can definitely lead to damage. Here are negatives if you don’t drain the water level down:
- Ice expansion can crack and pop the pool shell.
- Freezing water can destroy your skimmer.
- Valves and plumbing may burst from frozen water.
- Ladders, rails, and slides can be damaged.
- The cover will stretch from the weight.
- Chemistry is difficult to balance.
- Debris and algae accumulate in standing water.
For both safety and preventing costly repairs, it is highly recommended to drain pools below the skimmer before winter. Covering a fully filled pool often leads to extensive damage.
Maintain Some Water for Structure
While most water should be drained, you still want to avoid completely emptying the pool basin. Some water helps support the surrounding ground and prevents pressure issues. Leaving some water reduces the risk of compromising the structure over the winter.
Tips for Draining an Above Ground Pool
Above ground pools have different preparation steps for winter:
- Drain water level 2-3 feet below top rim
- Use sump pump if drain is not accessible
- Loosen liner and cover posts with foam
- Winterize pump and filter equipment
- Consider a pool cover or tarp
- Disconnect power to appliances
The principles are similar, but lowering the water level requires more effort in most above ground pools. Keeping the liner covered in water prevents sun and weather damage.
More Vulnerable to Freezing
Since above ground pools sit on top of the ground rather than in the ground, they are more exposed to cold air and freezing temperatures. Extra precautions may be needed in colder climates.
Refilling the Pool in Spring
When it’s finally time to reopen your pool after winter, use these tips for refilling:
- Remove cover and debris from pool
- Reconnect plumbing parts and hoses
- Make repairs to plaster, tile, or liner
- Reinstall ladders, rails, filters, and baskets
- Attach water hoses and start filling slowly
- Fill to marked level determined in fall
- Add chemicals and run filter as normal
- Inspect equipment and make repairs as needed
- Consider draining and refilling if water is murky
Take your time restarting equipment and systems. Refilling too quickly can overshoot the target level. Give chemicals time to disperse before using the pool.
Watch for Damage as Water Level Rises
Closely observe all areas of the pool as the basin refills. Any cracks, leaks, or shifting will be revealed as the water level climbs. Make repairs and adjustments immediately to prevent bigger issues.
Common Questions and Concerns
How much water should be drained from the pool?
As a standard guideline, water should be lowered to 6-12 inches below the skimmer opening. Vinyl pools can go halfway, while concrete pools drain up to 18 inches below skimmer level.
What problems can happen from not draining the pool for winter?
Freezing water can crack the pool shell and skimmer housing. Ice expansion also ruptures plumbing lines. Pool covers can collapse from the weight. Chemical imbalance and debris accumulate as well.
Should I turn off power to the pool before draining it?
Yes, you should shut off electricity to the pump, filter, and appliances before draining begins. This prevents equipment damage if water levels run too low. Never operate pool equipment without ample water.
How do I reopen my pool after winterizing?
In spring, reconnect plumbing parts, reinstall filters and baskets, and attach water supply hoses. Refill slowly to marked level. Add chemicals and run filter regularly. Make repairs as needed before normal use.
Can I leave my pool partially filled over winter?
You need to drain below the skimmer opening, but some water should remain. Leaving 1-2 feet in the deepest areas provides support and prevents groundwater pressure issues that could damage the pool structure.
Conclusion
Preparing your pool properly each fall is crucial to preventing costly freeze damage over winter. Draining below the skimmer opening eliminates many issues caused by ice expansion and standing water. This process also allows for full winterization of equipment and surfaces. Covering the lowered water level keeps out debris until spring. With the right preparation, your pool will be ready for another season of reliable swimmimg when warmer weather returns.