How To Blow Out Your Pool Lines Like A Professional
Winterizing your inground swimming pool requires completely clearing all subterranean plumbing lines of trapped water using a high-powered pool blower or air compressor to prevent catastrophic freeze damage. Achieving a successful blowout demands specific air volume delivery, strategic valve sequencing, and proper anti-freeze application to protect your investment through sub-zero temperatures.
Pre-Operation & Equipment Checklist
Proper preparation prevents structural cracking of PVC pipes, skimmer housing damage, and equipment failure during hard winter freezes. Before initiating the blow-out process, gather all necessary tools, verify your pool water chemistry, and clear the surrounding equipment pad.
- Essential gear, tools, and materials include a dedicated pool winterizing air blower (minimum 1.5 to 3 horsepower) or an oil-less air compressor capable of delivering 20 to 40 PSI, heavy-duty winterizing plugs with stainless steel bolts, expandable rubber plugs, non-toxic propylene glycol pool antifreeze (rated to at least -50 degrees Fahrenheit), pipe thread sealant tape, and a long-handled screwdriver or socket set.
- Mandatory prerequisite knowledge and standards dictate that you must lower the water level below the skimmer and return lines (typically 12 to 18 inches below the coping for vinyl liners, or just below the tile line for concrete), completely drain all filtration equipment, pumps, heaters, and chlorinators, and ensure atmospheric temperatures are consistently below freezing only after the procedure is finished.
- Estimated duration benchmarks range from 2 to 4 hours for standard residential configurations, with a professional tool investment or rental cost offsetting thousands of dollars in potential plumbing replacement expenses.
Step-by-Step Pool Plumbing Winterization Workflow
Step 1: Lower the Water Level and Clear the Equipment Pad
Begin by attaching a backwash hose to your multiport valve and pumping the pool water down to the correct level, ensuring no water remains in the skimmer throats. Next, remove the drain plugs from the pump housing, filter tank, chlorinator, and pool heater, storing them securely in the pump basket to prevent loss. Turn off all electrical power to the pump at the breaker panel to prevent accidental dry-firing during the procedure.
Warning: Never use automotive antifreeze or windshield washer fluid in your pool lines, as these formulas contain petroleum distillates that will permanently stain pool surfaces, damage liners, and introduce toxic chemicals into the water table.
Step 2: Blow Out the Skimmer Lines and Main Drain
Connect your air blower or compressor hose to the skimmer suction port or prime it through the pump basket housing using a specialized winterizing adapter plate. Direct high-pressure air through the skimmer lines first until a violent, bubbling boil erupts from the main drain at the deep end of the pool, indicating all water has been evacuated.
Pro-Tip: Once air bubbles continuously rise from the main drain, quickly insert a winterizing plug into the main drain valve at the equipment pad or use a standpipe mechanism to lock the air column in place before sealing the skimmer.
Step 3: Seal Skimmer Housings and Return Jets
With the main drain sealed, divert the air stream to blow out the individual return lines, working methodically from the return closest to the equipment pad to the farthest one. Watch each return jet in the pool until a continuous, fine mist of air droplets emerges, then immediately thread a threaded winterizing plug with an O-ring into the wall fitting. Pour a half-gallon of non-toxic propylene glycol directly down each skimmer throat before inserting a Gizzmo skimmer bottle to absorb any residual expansion forces.
Step 4: Finalize Above-Ground Plumbing and Cover Installation
Inspect all exposed unions, valves, and manifold connections to ensure absolute dryness, leaving valve handles in a semi-open or 45-degree position to prevent moisture from pooling inside the ball valves and cracking the PVC casings. Wrap your pool pump, filter, and heater in breathable, weather-resistant winter covers to protect them from windblown debris, UV degradation, and residual precipitation. Finally, pull your winter safety cover or solid tarp securely over the pool perimeter, anchoring it firmly with water bags or heavy-duty deck weights.
How To Blow Out Lines In Inground Pool: Essential Steps For Winter ...
Technical Parameters and Equipment Specifications
| Equipment Component | Recommended PSI / Power | Primary Function | Failure Risk if Omitted |
|---|---|---|---|
| Pool Air Blower | 1.5 to 3 HP (High Volume, Low Pressure) | Safely displaces water without overheating PVC | Pipe joint separation, thermal stress cracking |
| Air Compressor | 20 to 40 PSI (Regulated) | Alternative continuous high-pressure air source | High-pressure blowouts can rupture aged PVC lines |
| Non-Toxic Antifreeze | Propylene Glycol (-50°F rating) | Prevents condensation freeze-lock in vertical runs | Skimmer throat destruction, cracked underground lines |
| Expansion Gizzmo | 1.5-inch or 2-inch threaded plastic | Absorbs ice expansion pressure inside skimmer housing | Skimmer body collapse requiring excavation |
Common Site Failures and Field Fixes
- Root Cause: Air escapes through an unsealed skimmer or a loose union fitting during the blowout, preventing pressure from reaching the main drain.
- Actionable Fix: Check all above-ground valve positions, tighten clamp connections, and use a wet/dry vac or an inflatable winter plug to temporarily seal open skimmer ports while forcing air through alternate lines.
- Root Cause: Water pools back into the return lines due to an uneven slope or insufficient air displacement velocity.
- Actionable Fix: Increase blower output or switch to a high-volume compressor, clear the lines a second time, and immediately pour propylene glycol down the lines to displace remaining moisture droplets.
- Root Cause: The Gizzmo bottle cracks or pops out of the skimmer housing over the winter because it was installed without thread sealant tape or proper torque.
- Actionable Fix: Wrap the Gizzmo threads with three to four passes of PTFE thread tape, coat with pool lube, and thread it snugly into the skimmer base without over-tightening into brittle plastic.
Frequently Asked Questions
Can I use a standard shop vacuum to blow out my pool lines?
Yes, a high-capacity shop vacuum operating on the exhaust (blower) setting can successfully clear shallow pool lines on smaller above-ground pools or simple inground layouts. However, large inground pools with long runs and deep main drains typically require a dedicated pool winterizing blower or compressor to generate the necessary air volume.
How do I know when the main drain is completely clear of water?
You will know the main drain is completely clear when you observe a steady, vigorous stream of large air bubbles boiling aggressively across the deep end floor of the pool surface. Once this continuous boil is established, you must immediately close the main drain valve at the equipment pad to lock the air column inside the pipe.
Should I leave my pool filter pump connected during the winter?
No, leaving your pump, filter tank, and heater connected and full of water during freezing temperatures will result in cracked housings and destroyed internal grids or heater manifolds. All peripheral equipment must be fully drained, unplugged, and stored in a dry, protected environment like a shed or garage.
What happens if I forget to add antifreeze to the skimmer lines?
Skipping pool antifreeze leaves microscopic pockets of condensation vulnerable to freezing, expanding, and cracking the subterranean PVC lines or concrete skimmer throat. Repairing a cracked underground pool line requires costly excavation, concrete cutting, and professional plumbing reconstruction.
Protect Your Pool Investment All Year Long
Mastering the pool line blowout process ensures your backyard oasis survives harsh winter conditions and opens smoothly when swim season returns. Schedule your seasonal winterization routine well before the first hard freeze to guarantee structural integrity and peace of mind.
