How To Drain Your Pool: The Complete Professional Guide To Emptying And Resetting Your Basin

Draining a swimming pool requires careful management of hydrostatic pressure, local municipal discharge codes, and weather conditions to prevent structural collapse or surface etching. Executing this procedure safely involves utilizing a submersible utility pump, monitoring water tables, and preparing the empty vessel for immediate refilling or maintenance.

Pre-Operation & Equipment Checklist

Emptying a swimming pool is a major mechanical and structural procedure that should only be performed every five to seven years, or when total dissolved solids (TDS), calcium hardness, or stabilizer levels exceed critical chemical thresholds that water replacement is the only remediation. Before initiating this workflow, you must verify local environmental regulations regarding wastewater discharge, as pumping chlorinated or chemically balanced pool water directly into storm drains may violate municipal ordinances.

• Essential Gear, Tools, and Materials:

  
  
  
  • Submersible utility pump (minimum 1/4 to 1/2 horsepower with garden hose or discharge hose attachment)
  • Discharge hose (sufficient length to reach an approved sanitary sewer cleanout or legal drainage area)
  • Garden hose for residual rinsing and scrubbing
  • Heavy-duty pool brush with nylon bristles (avoid wire brushes on plaster or vinyl)
  • Non-toxic, pool-safe acid wash or surface cleaner (if removing severe staining or scaling)
  • Personal protective equipment (rubber gloves, safety glasses, and sturdy footwear)
  • Submersible sump pump (backup unit for heavy debris or puddling)

• Mandatory Prerequisite Knowledge and Standards:

  
  
  
  • Hydrostatic pressure assessment: Verify the local water table is low; never drain a pool during heavy rainfall or saturated ground conditions to prevent the shell from "popping" out of the ground.
  • Structural identification: Confirm whether your pool is concrete/gunite, vinyl-liner, or fiberglass, as each requires vastly different handling during and after the empty phase.
  • Discharge destination compliance: Route wastewater to a sanitary sewer cleanout or lawn area that can absorb heavy moisture without causing property erosion or neighbor disputes.

• Estimated Budget and Duration Benchmarks:

  
  
  
  • Time investment: 4 to 12 hours for active pumping, plus an additional 24 to 72 hours for refilling depending on local flow rates.
  • Financial cost: Zero if utilizing existing equipment, or $150 to $300 if renting heavy-duty commercial trash pumps or hiring professional waste-water hauling services.

Step-by-Step Drainage and Basin Reset Workflow

Step 1: Pre-Test Water Chemistry and Plan the Discharge Route

Begin by testing your pool water to ensure chemical levels are within acceptable limits for discharge. If chlorine levels are high, stop adding chlorine for 5 to 7 days prior to draining to let sunlight naturally dissipate the sanitizer, or utilize a sodium thiosulfate dechlorinator. Connect your discharge hose to the submersible pump and route it away from your foundation, neighbor's property, and storm drains, directing the flow toward an approved sanitary sewer cleanout or a wide, sloped lawn that can safely percolate the volume.

Warning: Never pump high-concentration chlorinated or saltwater directly onto delicate landscaping, as it will instantly kill grass, shrubs, and ornamental plants.

Step 2: Position the Submersible Pump and Initiate Pumping

Lower the submersible utility pump carefully into the deepest end of the pool, ensuring it sits flat on the floor and is not buried under thick leaves or heavy sediment. Plug the pump into a Ground Fault Circuit Interrupter (GFCI) protected outlet, preferably utilizing a heavy-duty outdoor extension cord rated for wet locations. Turn on the pump and monitor the initial outflow to ensure the discharge hose is secure, free of kinks, and moving water efficiently away from the basin.

Step 3: Monitor Water Levels and Manage Debris Accumulation

As the water level drops, walk the perimeter of the pool to check for any anomalies or structural settling. As the remaining water pools in the deep end, sweep residual leaves, twigs, and sludge toward the pump intake, but take care not to let the pump ingest large debris that could clog the impeller. If your pump lacks an automatic shut-off float switch, monitor the progress closely to prevent the motor from running dry, which will quickly burn out the internal seals.

Step 4: Execute Hydrostatic Pressure Relief (Concrete Pools Only)

For concrete and gunite pools built in areas with high water tables, locate the hydrostatic relief plugs situated at the very bottom of the deep end floor and open them immediately once the water level drops below the main drain. Opening these brass or PVC plugs allows subterranean ground water to enter the pool rather than building up immense pressure beneath the shell, which can crack the concrete or lift the entire structure out of the earth.

Pro-Tip: Leave hydrostatic relief plugs open throughout the entire duration the pool is empty, and only retighten them immediately before you begin refilling the basin with fresh water.

Step 5: Perform Immediate Surface Cleaning and Acid Washing

Once the pool is completely empty, inspect the interior surfaces while they are still damp. For standard plaster pools, scrub the walls and floor with a mixture of pool cleaner and water to remove mineral rings, algae roots, and grime. If stubborn calcium scaling or severe staining persists, perform a professional acid wash by diluting muriatic acid with water in a plastic watering can, applying it systematically from the shallow end down, and neutralizing the runoff with soda ash before rinsing it directly to the waste port.

Step 6: Inspect Structural Elements and Initiate Refilling

Before turning the water back on, inspect all return fittings, skimmer throats, main drain grates, and underwater light niches for cracks, loose gaskets, or deteriorating mastic expansion joints. Once repairs are completed and hydrostatic plugs are securely closed, place multiple garden hoses into the deep end of the pool to begin the uninterrupted refilling process. Never stop the filling process once started until the water reaches the middle of the skimmer opening, ensuring even, uniform pressure distribution across the entire structural shell.

Pool Surface Matrix and Drainage Parameters

Common Site Failures and Field Fixes

• Root Cause: The pool shell shifts, cracks, or lifts out of the ground during or immediately after draining due to saturated surrounding soil.

  
  
  
  • Actionable Fix: Always verify local weather patterns and hydro-geological conditions before draining. Ensure hydrostatic relief valves are fully opened on concrete pools, and never drain pools in clay-heavy soils during rainy seasons.

• Root Cause: The vinyl liner shrinks, pulls away from the track, and becomes brittle, making it impossible to reinstall.

  
  
  
  • Actionable Fix: Never drain a vinyl-liner pool completely on a hot, sunny day. If a partial drain is required for repair, leave at least one foot of water in the deep end and prop the liner if necessary.

• Root Cause: The submersible pump motor burns out or trips the breaker continuously during the drainage process.

  
  
  
  • Actionable Fix: Ensure you are using a dedicated 15-amp or 20-amp GFCI circuit with an appropriately gauged outdoor extension cord. Keep the pump intake clear of heavy leaves and sediment sludge to prevent cavitation and motor overheating.

• Root Cause: Severe chemical staining or etching appears on the plaster surface as the water recedes and dries.

  
  
  
  • Actionable Fix: Keep the interior plaster wet by spraying down walls with a garden hose periodically during the drainage process, and perform your acid wash or surface cleaning immediately before the mud and scale can bake into the pores.

Frequently Asked Questions

Can I drain my pool completely by myself?

Yes, homeowners can successfully drain a swimming pool using a standard submersible utility pump, provided they follow strict safety guidelines regarding hydrostatic pressure, local discharge laws, and surface material limitations. However, vinyl-liner and fiberglass pools carry significantly higher risks of structural failure and often require professional intervention to avoid catastrophic damage.

How long does it take to drain and refill a typical swimming pool?

Pumping out a standard 15,000 to 20,000-gallon residential pool usually takes between 6 to 12 hours using a standard 1/2 horsepower submersible pump. Refilling the pool with municipal tap water typically takes anywhere from 24 to 72 hours, depending on your home's water pressure and flow rate per minute.

Is it safe to drain a pool in the middle of summer?

Draining a pool in the peak of summer exposes plaster, concrete, and vinyl surfaces to intense ultraviolet radiation and extreme heat, which can crack plaster, bake scale permanently into surfaces, and cause vinyl liners to shrink rapidly. Whenever possible, schedule your pool draining for mild, overcast spring or autumn days.

What should I do with the wastewater when emptying my pool?

You must check local municipal codes, as many cities prohibit discharging chlorinated pool water into storm sewers because it harms aquatic life in local waterways. Route your discharge hose to an approved sanitary sewer cleanout on your property or distribute the water slowly across a large, well-draining lawn area where chlorine can safely dissipate.

Why do I need to leave water in a vinyl-liner pool?

Vinyl pool liners rely on the immense weight of the water column to press the material firmly against the walls and floor of the supporting structure. If you remove all the water, the liner will quickly lose its tension, shrink from ambient air temperature, pull out of the coping tracks, and suffer irreversible distortion.

Ensure the long-term structural integrity and water quality of your backyard oasis by pairing safe drainage practices with professional water chemistry balancing. Consult with our certified technicians today for expert assistance with complex pool renovations and seasonal maintenance plans.