Once associated exclusively with luxury hotels and high-end residences, overflow pools are now increasingly integrated into private gardens worldwide. Beyond their visual impact, they offer measurable technical advantages — superior water quality, more efficient filtration, and reduced maintenance compared to traditional skimmer systems.
What is an overflow pool?
In an overflow pool, water spills continuously over a weir — partial or total — and is collected by a gutter surrounding or running beneath the pool. A balancing tank equipped with a water level sensor compensates for variations caused by bathers, evaporation, and rainfall. From there, a filtration pump returns the water to the pool, maintaining a continuous and stable hydraulic circuit.
Types of overflow swimming pools
Choosing the right overflow system depends on several factors: the topography of the site, available space, the relationship between pool and house, architectural style, and the desired visual effect.
Infinity edge overflow pools
Among all overflow pool configurations, the infinity edge is the most sought-after. The negative edge weir allows water to flow continuously over the edge, creating the impression that the pool has no boundary — the water line appears to merge with the horizon. The waterfall effect can be modulated to produce a quieter, more discreet flow. On a sloped or terraced site, the visual impact is particularly striking.
Zero edge overflow pools
In a perimeter overflow pool, water spills over all four sides. The edges blend seamlessly into the surrounding deck — there is no coping, and the water surface sits at exactly the same level as the terrace. As water spills from the pool, it flows into a channel installed under a slot or grate, then into a balancing tank at a lower level.
This configuration works particularly well in a garden or on a terrace adjacent to the house, creating a calm, mirror-like atmosphere. The reverse slopes of the channel reduce water loss and ensure a quiet, controlled return.
Mixed overflow pool designs
It is possible to combine both systems — a negative edge weir on one side and a perimeter overflow on the other three. This configuration captures a directed view while maintaining the Zen calm of a zero-edge finish on the remaining sides. The visual result is exceptional.
The design and operation follow the same principles as the individual systems. A preliminary design allows you to visualise the result before construction begins.
Note: contrary to a common misconception, a standard pump is sufficient for overflow pools — no specific pump is required.
Morana's advice
Choosing the right overflow for your pool
Selecting the right overflow configuration is one of the most consequential decisions in a pool project. Each option — infinity edge, zero edge, or mixed — responds to a specific site, view, and architectural context. Professional advice at this stage prevents costly adjustments later.
Surround yourself with the right people
Once the design and technical plans are in place, the quality of execution depends entirely on the skill of the teams on site. A well-detailed plan is only as good as the contractor who builds it.
Overflow pool benefits and disadvantages
The disadvantages
An infinity edge or zero-edge pool costs approximately 20% more than a standard skimmer pool. The difference reflects the construction of the overflow gutter, the balancing tank, and a slightly oversized filtration system. A negative or zero edge pool requires a designer with specific experience in overflow hydraulics — this is not a project that can be handed to a general pool contractor without detailed technical plans.
The benefits
The overflow filtration system prevents impurities from accumulating at the water surface. Leaves, insects and other debris are continuously removed by the overflow. Return inlets at the pool floor ensure better distribution of treatment products and heated water, simplifying maintenance.
A zero-edge pool appears to sit flush with the terrace — the walls dissolve into the water surface. An infinity pool creates the impression that water extends to the horizon, merging with the landscape beyond.
Overflow pool design process
Designing an overflow pool requires more than technical execution. When non-specialised contractors are involved, clarity at the design stage becomes essential. Accurate drawings and well-defined reference levels ensure that the project can be executed correctly, even by teams without specific overflow pool experience.
A preliminary design phase allows the project to be shaped in relation to the site, the surrounding architecture and the intended use of the pool. Decisions about proportions, positioning and visual relationships are established at this stage, long before construction begins.
For a broader, design-led perspective — where proportions, alignment and visual intent are defined before technical decisions — explore our Infinity Pool Design & Construction Guide.
Drawing the plans
In addition to the general plan, section drawings, execution details and hydraulic layouts are required. When calculating the volume of the balancing tank, the dimensions of the pool, the type of overflow and the length of the overflow edge must all be taken into account. The frequency of use is also a factor.
Conclusion
Overflow pools combine aesthetic intent with hydraulic precision. Whether the project calls for an infinity edge, a zero-edge perimeter finish, or a mixed configuration, each system responds to a specific site, view and architectural context.
The investment is justified by long-term performance — easier maintenance, superior water circulation, and a visual result that a standard skimmer pool cannot achieve.
Morana Water Design has been designing overflow pools internationally for over 30 years. From preliminary concept to full technical execution, our plans give your project the precision it requires.
Frequently Asked Questions — Overflow Swimming Pools
What is the difference between an overflow pool and an infinity pool?
Overflow pool is the technical term describing the water circulation system. Infinity pool refers specifically to pools with a vanishing edge effect where water appears to merge with the horizon. All infinity pools are overflow pools, but not all overflow pools are infinity pools.
How much does an overflow pool cost compared to a regular pool?
An overflow pool typically costs 20% more than a standard skimmer pool. The additional cost covers the overflow gutter system, balancing tank construction, and a slightly oversized filtration system.
Can overflow pools be built on any terrain?
Overflow pools can be built on various terrains, but sloped sites are ideal for infinity edge effects. Flat terrain works well for zero-edge designs. Professional assessment of topography, drainage and structural requirements is essential for optimal results.