How To Drain A Pool Using The Pool Pump
Lowering or emptying a swimming pool using its existing filtration system requires setting the multiport valve to the waste position to bypass the sand or DE filter entirely. Executing this process incorrectly can cause catastrophic liner shrinkage, structural hydrostatic uplift, or burn out your pool pump motor by running it dry.
Pre-Operation & Equipment Checklist
Lowering your swimming pool water level is occasionally necessary for water chemistry resets, localized surface repairs, or seasonal winterization. Utilizing your existing circulation equipment rather than renting a submersible utility pump is efficient, but it requires precise operational control. Neglecting pre-operation planning can lead to flooded yards, damaged property, or severe damage to your pump's mechanical seals and wet end.
- Essential gear and tools: Backwash hose or a flexible discharge hose matching your waste port diameter, heavy-duty hose clamps, wire brush, pH and total alkalinity test kit, and a submersible safety backup pump just in case.
- Mandatory prerequisite knowledge: Local municipal ordinances regarding chlorinated wastewater discharge, hydrogeological awareness of your local water table, and familiarity with your specific pump horsepower and flow rate (typically ranging from 40 to 90 gallons per minute).
- Estimated budget and duration benchmarks: Zero cost if you already own a discharge hose; 1 to 4 hours of active monitoring depending on pool volume and the depth of water being removed.
Step-by-Step Drainage Execution Workflow
Step 1: Inspect Local Regulations and Hydrostatic Conditions
Before turning a single valve, verify your local municipality's codes regarding chlorinated or salt-water discharge into storm drains or yards. Simultaneously, investigate your local water table conditions. If you live in an area with high groundwater saturation, completely emptying a pool can result in the entire shell popping out of the ground due to unchecked hydrostatic pressure.
Warning: Never drain a vinyl-liner pool completely without the direct supervision of a pool professional. As water is removed, the liner shrinks rapidly, losing its elasticity and pulling away from the coping tracks permanently.
Step 2: Attach the Discharge Hose to the Waste Port
Locate the waste or backwash port on your multiport valve, which is typically threaded with a 1.5-inch or 2-inch male pipe thread (MPT). Screw a barbed hose adapter into this port and secure a heavy-duty backwash hose over the fitting using a corrosion-resistant stainless-steel hose clamp. Unroll the discharge hose completely down your property slope, ensuring it leads to a legal sanitary sewer cleanout or an approved drainage ditch away from your foundation and your neighbor's property.
Step 3: Power Down the Filtration System
Always turn off the circuit breaker supplying power to your pool pump before touching the multiport valve handle. Attempting to rotate a multiport valve while water is actively pumped under high pressure can score the internal spider gasket, destroying the seal and causing severe leaks across all filter settings.
Step 4: Adjust the Multiport Valve to Waste
Push down firmly on the multiport valve handle, rotate it clockwise until the indicator arrow points squarely to the Waste or Drain position, and release the handle to lock it securely into the notch. This internal mechanism routes water entering from the skimmers and main drains directly out of the waste port, bypassing the filter medium entirely so debris-heavy water and chemical sludge do not clog your sand, cartridge, or diatomaceous earth grids.
Step 5: Prime, Execute, and Monitor the Drainage Process
Turn the pool pump circuit breaker back on to initiate drainage. Because you are pulling water through an extended discharge line, verify that the pump primes successfully and water is flowing steadily out the end of the discharge hose.
Pro-Tip: Never leave a pool pump running unattended while draining. If the water level drops below the skimmer openings, the pump will begin sucking air, lose its prime, and overheat within minutes, melting the impeller and destroying the shaft seal.
Step 6: Shut Down When the Target Level is Reached
Once you have lowered the water to your desired depth, immediately turn off the pump at the breaker. Return to the multiport valve, depress the handle, and turn it back to the standard Filter position. Disconnect the discharge hose, store it out of direct sunlight, and restore your chemical balancing routine as soon as refilling begins.
How to prime a hose to drain a pool cover - kloand
Pool Drainage Method Comparison Matrix
| Drainage Parameter | Multiport Waste Valve Method | Submersible Utility Pump Method | Siphon Hose Method |
|---|---|---|---|
| Equipment Cost | Low (Hose purchase only) | Medium ($100 to $250 purchase) | Low (Garden hose or PVC) |
| Flow Rate Efficiency | High (40 to 90+ GPM) | Medium (15 to 45 GPM) | Very Low (2 to 5 GPM) |
| Risk of Pump Damage | High (Dry-running hazard) | Low (Self-contained unit) | None |
| Operational Complexity | Medium (Requires valve manipulation) | Low (Plug and play) | High (Prone to losing prime) |
Common Site Failures & Field Fixes
- Root Cause: The pool pump loses its prime mid-drain, making a loud screeching sound and failing to move water.
- Actionable Fix: Immediately turn off the breaker. Check for obstructions in the skimmer basket, verify that the water level hasn't dropped below the skimmer faceplate, and fill the pump strainer pot with water to re-establish a prime before restarting.
- Root Cause: Water leaks out of the waste port even when the multiport valve handle is set to a different position.
- Actionable Fix: The internal spider gasket is worn, torn, or dislodged. Power down the system, unscrew the top cover of the multiport valve, inspect the rubber gasket, and replace it with an OEM-matched replacement part using silicone-based lubricant.
- Root Cause: The discharge hose balloons, detaches from the fitting, or bursts under backpressure.
- Actionable Fix: Replace cheap, thin plastic film backwash hoses with a reinforced vinyl or heavy-duty heavy-duty blue discharge hose, and double-clamp the connection using dual stainless-steel gear clamps.
Frequently Asked Questions
Can I drain my pool completely using just the pool pump?
You can lower the water level significantly, but you should rarely drain a pool completely unless you are executing major structural renovations. Completely emptying concrete, fiberglass, or vinyl pools introduces extreme risks of wall collapse, liner failure, or hydrostatic floating.
Where should I direct the wastewater when draining my pool?
You must direct pool water to a sanitary sewer cleanout on your property or a legal stormwater drainage area that complies with local environmental regulations. Avoid routing chlorinated or salt water directly onto sensitive landscaping, vegetable gardens, or neighboring properties.
Why is my pump losing prime while draining the pool?
A pump loses its prime during drainage typically because the water level in the pool has dropped below the mouth of the skimmers, causing the system to pull air instead of water. To prevent this, monitor the pool continuously and shut down the system when the water is a few inches above the skimmer bottom.
How do I protect my pool liner while lowering the water?
Never drain a vinyl-liner pool entirely on a hot sunny day or leave it empty for more than 24 hours. The vinyl material loses its plasticizers and shrinks rapidly when exposed to air and heat, preventing you from safely refilling the pool without destroying the liner.
Master Your Pool Maintenance Strategy Today
Keep your swimming pool operating at peak efficiency by pairing correct equipment operation with proactive seasonal water management. For complex plumbing configurations or total structural rehabilitations, consult a licensed pool professional to protect your investment.
