Draining a pool sounds straightforward until you are standing there an hour in, watching the water level barely move. The method you use makes an enormous difference. Done right, a standard above-ground pool can be emptied in a few hours. Done wrong, you are waiting all day, or worse, damaging your pump in the process.
This guide covers the fastest ways to drain a pool, what equipment gives you the best speed, and the key precautions that protect your pool, your garden, and your drainage system throughout.
Key Takeaways
- A submersible pump is the fastest method for emptying a pool quickly – significantly faster than gravity or filter-based draining
- Never run a pump dry – always monitor water levels and switch off before the pump loses suction
- Chlorinated pool water should not be discharged onto lawns, into watercourses, or near planted areas
- In Portugal, drain to a sewer connection or cesspool – check local regulations before discharging large volumes
- Inground pools should never be fully drained without professional guidance – hydrostatic pressure can lift or crack the shell
- Above-ground pool liners should not be left empty and exposed to sun for extended periods
When Should You Empty a Pool?
Draining is not part of regular pool maintenance – in fact, it should happen as rarely as possible. Water removal puts stress on liners, risks pump damage, and requires responsible disposal of treated water.
That said, there are clear situations where draining becomes necessary. High total dissolved solids (TDS) that can no longer be corrected by chemical treatment, a full seasonal close with storage, major repairs to the liner or structure, or persistent algae contamination that has not responded to treatment – all are legitimate reasons to empty the pool.
If you are draining simply because the water looks bad, it is worth attempting a full shock and clarifier treatment first. A proper chemical reset is faster, cheaper, and far less disruptive than a full drain and refill.
The Fastest Methods to Empty a Pool
Submersible Pump
This is the quickest option available and the one to choose when speed matters. A submersible pump sits directly in the water and pushes it out through a connected discharge hose. Flow rates vary by pump size – a pump moving 500 litres per minute will drain a standard above-ground pool in two to three hours.
Place the pump at the deepest point of the pool for maximum efficiency. Direct the discharge hose to an appropriate drainage point before switching on. As water levels drop, reposition the pump to keep it submerged and maintain suction.
Most submersible pumps struggle with the final few centimetres of water. A flat-bottom pool will leave a thin layer that the pump cannot reach – a mop, sponge, or wet vacuum handles this last step more practically than waiting for the pump to labour through it.
Pool Filter on Waste Setting
If your pool has a sand or DE filter with a multiport valve, the waste setting bypasses the filter and discharges water directly out of the system. This is a useful method for partial drains, lowering the level by 20–30 cm during maintenance, and is faster than running on filter mode.
Switch the pump off before rotating the multiport valve. Turn to the waste position, then restart the pump. Monitor the water level continuously and switch off before the water drops below the skimmer line. Running the pump dry causes immediate damage to the impeller and seals.
For cartridge filter systems without a multiport valve, use the drain plug at the back of the filter housing or a three-way valve between the pump and filter if your setup includes one.
Gravity Drain (Built-in Drain Valve)
Most Intex and similar above-ground pools include a drain valve at the base of the pool wall. Connect a garden hose adaptor and run the hose to a suitable drainage point. Gravity does the work and there is no power required.
The obvious limitation is speed. Gravity drainage is slow, and with a large pool it can take the better part of a day. It is, however, completely passive and requires no additional equipment. For small pools or situations where you simply want to leave it running overnight, it works fine.
Tilt the pool gently toward the drain once most of the water has gone to clear the remaining volume. The last few litres will pool in the low corner but a sponge or small wet vacuum handles this more efficiently than waiting.
Siphon Method
A siphon requires nothing more than a long hose and a lower endpoint than the pool. Submerge the hose completely to fill it with water, seal both ends with your thumbs, then place one end at the bottom of the pool and the other at your discharge point below pool level. Release both ends and gravity draws water continuously through the hose.
This method works and costs nothing, but flow rate is limited by hose diameter. It is best suited to small above-ground pools or situations where no pump is available. For a large pool, use a submersible pump instead and you will see that the time difference is significant.
How to Drain an Above-Ground Pool Quickly: Step by Step
- Choose your method. For speed, use a submersible pump. For a partial drain, use the filter waste setting. For a simple low-effort drain, use the gravity valve or siphon.
- Plan your discharge point. Pool water treated with chlorine, algaecide, or other chemicals cannot be discharged onto lawns, into garden beds, near trees, or into open watercourses. The chemicals harm vegetation and can affect soil biology. Direct water to a municipal sewer connection, cesspool, or storm drain, and in Portugal, verify local regulations for large-volume discharges before you begin.
- Set up before starting. Position the pump, extend the discharge hose its full length to the drainage point, and confirm there are no kinks restricting flow. A kinked hose reduces flow rate dramatically.
- Monitor continuously. Do not leave a running pump unattended. As water levels drop, pump position may need adjusting. Switch off before the intake loses suction – the sound of the pump tone changing is usually the first sign the water is too low.
- Handle the last few centimetres. No pump drains a pool completely flat. Use a wet vacuum, mop, or sponge to remove the remaining water from the pool floor before folding or leaving the liner exposed.
- Dry and protect the liner. If storing the pool, allow the liner to dry fully in the sun before folding – at least an hour of direct sun. Dust with talcum powder to prevent the walls from sticking and to absorb residual moisture.
What to Do With the Water
This step is skipped in most guides and it should not be. Chlorinated water discharged carelessly causes real damage.
Direct discharge onto a lawn will brown or kill grass, particularly with high chlorine levels. Water that flows into a ditch, stream, or irrigation channel introduces chemicals into the local ecosystem. In areas of Portugal with septic systems, large volumes of chemically treated water can disrupt the bacterial balance needed for the system to function.
The safest option is always a municipal sewer connection. If that is not available, allow chlorine to dissipate naturally before draining by stopping chlorination a week before and leaving the pool uncovered in sunlight – chlorine breaks down with UV exposure. Test the water before draining: a chlorine level below 0.1 ppm is generally safe for soil discharge.
Draining an Inground Pool: A Different Set of Rules
Everything above applies to above-ground pools. Inground pools require a fundamentally different approach and in most cases should not be drained without professional involvement.
The reason is hydrostatic pressure. An inground pool shell – whether concrete, fibreglass, or vinyl – is balanced by the weight of the water inside it. Remove that water and the surrounding soil pressure, combined with groundwater beneath the shell, can physically lift the pool out of the ground or crack the structure. This is not a rare worst case – it happens, and the repair costs are significant.
If an inground pool genuinely needs full draining, consult a pool professional who can assess groundwater conditions, relieve hydrostatic pressure through dedicated relief valves, and advise on safe timing.
Draining a Natural Pool: A Completely Different Question
Natural swimming ponds are not drained the way conventional pools are, and most do not need to be. The water is part of a living system supporting plant life, biological filtration and the microbial balance that keeps the water clean without chemicals.
Draining a natural pool removes that balance entirely and requires rebuilding it from scratch. For cleaning, maintenance or water quality adjustment, targeted interventions – selective plant management and partial water exchange – are almost always preferable to a full drain.
At Oásis Biosistema, our natural swimming ponds are designed so that a full water change is never required. The combination of mechanical filtration, UV sterilisation, ozone technology and a white quartz sand base keeps the water permanently crystal clear without the seasonal draining cycles that conventional pools demand. If you are finding that the maintenance demands of a conventional pool are starting to outweigh the enjoyment, it is worth understanding what a different kind of water feature can look like.
Conclusion
Emptying a pool quickly comes down to having the right equipment and a clear plan before you start. A submersible pump with a good flow rate, a properly routed discharge hose, and continuous monitoring will get most above-ground pools drained in a few hours rather than a full day.
The parts that slow people down are almost always the same: starting without a discharge route planned, leaving a pump running unattended until it runs dry, or underestimating how much time the last few centimetres take without the right tool. Get those details right and the job is straightforward.
Drain responsibly, protect the liner, and if you are draining to close for the season – do it at the right time, with the chemistry balanced, so the pool is ready to go the moment the water comes back.
FAQ
What is the fastest way to empty a pool?
The submersible pump is fastest, draining pools in 8–14 hours depending on size. Two-inch pumps move 1,800 to 2,400 gallons hourly. Alternatively, rent trash pumps moving 10,000+ gallons per hour for large pools. Position the pump at the deepest point and discharge away from foundations. Faster than siphoning or garden hoses which take days to drain pools.
How do I clear a pool in 24 hours?
Shock the pool heavily (triple dose), run the filter continuously, brush walls and floor vigorously, add clarifier or flocculant, backwash the filter frequently, and balance pH (7.2–7.6). Use algaecide for green water. Vacuum debris to waste. Test and adjust chlorine levels. Crystal-clear water requires proper chemistry, circulation and filtration working together consistently.
How do I get water out of my pool without a pump?
Siphon water using a garden hose: submerge the hose completely, cap both ends, place one end in the pool and the other downhill outside, then release the caps. Gravity drains the water slowly. Alternatively, use a wet vacuum for small amounts or bail manually with buckets (extremely slow). Submersible pumps remain the most practical method.
Can I drain my pool with a garden hose?
Yes, drain pools using the garden hose siphon method: fill the hose with water, seal both ends, place one end in the pool and the other end downhill below water level, then release. Gravity creates a siphon draining slowly (20–48 hours for average pools). Faster with larger diameter hoses. Submersible pumps drain much faster than siphoning.
