An infinity pool looks like the simplest thing in the world: water that disappears over an edge instead of stopping at a wall. Underneath that effect sits one of the most engineering-intensive pool types you can build, and getting it wrong does not mean a slightly untidy edge. It means the effect does not work at all.
One or more edges of the pool sit lower than the water level, so water constantly spills over into a narrow trough called a weir or catch basin. From there it drains into a separate holding chamber, a balance tank, positioned below the main pool. A pump then returns that water to the main pool. That is what keeps the system balanced.
The balance tank is not optional and it is not small. It has to hold enough water to absorb the volume that spills over during normal use, swimmers displacing water, wind, and rain, without overflowing itself or running dry. Every infinity pool is really two connected vessels: the pool you swim in, and a second tank you never see.
A standard pool needs a shell, a filtration circuit, and a skimmer or two. An infinity pool needs all of that plus a second structural tank, a separate set of pipework to move water between the two, and controls dedicated specifically to running the overflow edge. The pump handling the weir typically runs on a variable speed drive so the overflow rate can be tuned rather than left to blast at full pressure.
None of that is decorative. The balance tank has to be excavated, waterproofed, and structurally sound in its own right, sitting below grade and often below the water table depending on the site. The additional pipework and controls needed to run the skimmer edge are a permanent running cost as well as an installation one, since that pump operates continuously whenever the effect is active.
On a conventional pool, a coping edge that is a few millimetres out of level is invisible. On an infinity pool, it is the entire problem. Water only spills evenly along the vanishing edge if that edge is level to within a couple of millimetres across its full length. Even a small deviation means water pools thicker at one end and barely trickles at the other. That breaks the sheet effect that makes the pool look infinite in the first place.
This is why infinity pools are not a retrofit-friendly feature and why the build tolerance matters more here than on any other pool decision. Get the edge wrong by even a small margin during construction and there is no adjustment that fixes it afterwards without rebuilding the edge itself.
Constantly moving water loses heat and water faster than still water. An infinity edge keeps a thin sheet of water in motion and exposed to air across its full width, which increases evaporation compared with a standard pool of the same surface area. That means higher water loss (more top-up needed) and higher heat loss (more energy to maintain temperature), both as an ongoing running cost rather than a one-off.
This is worth factoring in at the planning stage, not discovering after the first winter. It is one of the reasons infinity pools suit climates and use patterns where the pool runs for extended periods rather than sitting idle, since the running cost is tied to how long the overflow effect is active, not just to pool size.
Given the evaporation and heat loss the overflow edge creates, an infinity pool should always be fitted with a cover. Specifically a slatted floating cover rather than a simple solar cover, since it needs to sit properly against a moving water edge rather than a static one. Alongside the cover, the pool needs controls that let you switch the skimmer edge off entirely when the pool is closed.
Running the overflow effect continuously, day and night, whether anyone is using the pool or not, is the single easiest way to turn an infinity pool's running costs into a genuine problem. A cover plus the ability to stop the edge on demand turns it back into a feature you control rather than a system that runs regardless.
If the full infinity edge is more engineering and running cost than you want to commit to, a deck level pool gets you most of the visual effect for a fraction of the complexity. A standard pool sits with the water roughly 150mm below the coping. A deck level pool holds the water within around 15mm of the coping, so it reads as flush with the surrounding patio rather than sitting in a visible basin.
Because the water is not spilling continuously over an edge into a separate balance tank, a deck level pool does not need one. It does need a specialist skimmer designed to work at that reduced water depth, along with additional controls on the pipework to manage the finer water-level tolerance. That is real added complexity compared with a standard pool, but nowhere near the balance tank, dedicated overflow pump, and evaporation profile of a true infinity edge. For a lot of gardens, that is the honest answer. Origin Aqua would rather tell you that upfront than let a sales conversation about the full infinity edge run long before anyone mentions it.
Debris collects in the catch basin the way it never does on a standard pool, since every leaf and bit of grit that lands anywhere near the edge eventually washes over and sits in the trough. That basin needs checking and clearing regularly, not just at the start of the season.
The overflow pump works harder than a standard filtration pump, since it runs whenever the edge is active, so servicing intervals are shorter. The balance tank water level also needs monitoring: too low and the pump risks running dry, too high and the tank can overflow into areas it was never meant to reach. It is one more thing to stay on top of, and most new owners underestimate how much attention it needs in the first year.
That depends on what you are optimising for. If the priority is the visual effect and the site has a view worth framing, a slope down to water, open countryside, a coastline, an infinity pool delivers something no conventional pool shape can. Without a view to frame, most of the justification disappears, since the entire point of the design is what happens at the edge you are looking past.
If the priority is running cost and low maintenance, the balance tank, dedicated pumps, and evaporation losses make it one of the more demanding pool types to own. A deck level pool is worth considering before committing to the full infinity edge, since it closes most of the visual gap without closing the cost gap in the same way.
Not fundamentally. Whether water overflows into a balance tank and returns, or simply recirculates through a standard skimmer, biological filtration acts on the whole water volume, not on how it physically moves around the site. Origin Aqua's Mineral+Biome® system works the same way regardless of pool architecture. An infinity edge does not need a different or additional water treatment approach.
The same rules apply as for any garden pool: most fall under permitted development, but the balance tank excavation and any retaining structure needed for a sloped site can bring in additional considerations. See our full planning permission guide before finalising the design.
The overflow edge is only a few centimetres of vertical drop into the catch basin, not a cliff edge. The weir is designed at a height and width that lets water spill over evenly, and the drop into the basin is shallow and contained, not a fall hazard in normal use.
The recurring issues are all downstream of the same root cause: the balance tank and overflow system. Debris collecting in the catch basin, higher evaporation and heat loss, the overflow pump running continuously if there is no cutoff control, and construction tolerance issues if the edge was not built level enough in the first place.
Expect a meaningful premium over a standard pool of the same size, driven by the balance tank construction, the dedicated overflow pump and controls, and the added precision required during the build. See our full UK swimming pool cost breakdown for the base figures an infinity pool builds on top of.
As safe as any other pool when built correctly. The overflow edge itself is not a safety hazard, since the drop into the catch basin is shallow. Standard pool safety considerations, fencing, alarms, and supervision, apply the same way they would to any pool.
If the site has a view and the visual effect matters to you, yes. If low running cost and simplicity matter more, a deck level pool or a standard pool will suit you better. It is a genuine trade-off, not a straightforward upgrade.
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