Infinity pools, vanishing edges and perimeter overflow.
The edge that disappears into the view is a hydraulic system as much as a design. On the right site, from Montecito to Malibu, nothing else comes close.
An infinity pool, also called a vanishing edge, keeps the water level exactly at the top of one wall so it spills continuously over a weir into a catch basin below, where a dedicated pump returns it to the pool. The illusion works when the edge is dead level, the basin is sized for surge, and the site falls away behind the wall. It is a second vessel with its own hydraulics, which is why it adds meaningfully to engineering and cost. Perimeter overflow applies the same idea to every edge.
How the edge works
One wall of the pool, the weir, is built to a precise height and the water is held a fraction above it, so a thin sheet flows over the edge at all times. Below and behind the weir sits the catch basin, a trough that collects the overflow. A dedicated edge pump draws from the basin and returns water to the pool, so the sheet never stops while the system is running. The main circulation, filtration and heating run separately.
Three things decide whether the effect is right. The weir must be level to within a few millimeters along its full length, or the sheet breaks into streams; we set the tile on the weir with a laser and check it before the water goes in. The basin must hold the surge: the volume displaced when people get in, the wind-driven wave on an exposed site, and the evaporation between top-ups. And the edge pump must be sized to the length of the weir, because a long edge with a small pump runs dry in a breeze.
Where it belongs
The edge needs a fall behind it, because the illusion depends on seeing nothing but view beyond the water. Hillside lots in Montecito, the Riviera, Hope Ranch, Malibu and the Conejo hills are the natural sites. On a flat lot the edge can still be built as a raised wall with a basin below, spilling toward a lower terrace, and that version reads as a feature wall rather than a disappearing edge.
Wind is the other siting question. A bluff-top pool in Malibu takes wind across the sheet every afternoon, and the basin and pump are sized for it. It is routine engineering, but it is engineering, and it is one reason we walk the site before we draw.
What it adds
Structurally, the weir wall and basin are a second vessel, engineered and steel-tied to the shell and often sitting on the steepest part of the lot, which means footings, caissons or a grade beam and a soils report. Hydraulically, it is a second pump, a second set of plumbing, an autofill and a level control. Visually, it is the most tile you will buy for any pool, because the weir, the basin and the wall face are all finished. In our recent projects, an infinity edge on a hillside sits in the upper part of our estate range; the cost guide explains where.
Perimeter overflow and knife edge
Perimeter overflow takes the vanishing edge all the way around: the water level sits flush with the deck on every side and spills into a slot or a hidden gutter, so the pool reads as a flat plane of water set into the terrace. A knife edge is the version with a barely visible slot. Both need a surge tank sized for the whole perimeter and a deck built to a tolerance most decks are not, and both are the most demanding pools we build. On a modern house with a rectilinear plan, nothing else looks like it.
Living with one
An edge pool uses more water to evaporation than a conventional pool, because the sheet exposes more surface, and the edge pump is one more piece of equipment on the pad. Automation handles both: the edge runs on a schedule, the autofill keeps the basin level, and the whole system sits on one controller. A cover on the main vessel keeps evaporation and heat loss down when the pool is not in use, and it is required by the 2025 Energy Code on heated outdoor pools.
Sources
Requirements change and every parcel is different. Verify with the jurisdiction before relying on any figure here; we do, on every job.
Questions we are asked
Infinity pool or vanishing edge: what is the difference?
None. Infinity edge, vanishing edge, negative edge and disappearing edge all describe the same construction: a weir wall the water flows over into a catch basin. Perimeter overflow and knife edge are related designs where the water spills on every side.
Can you build an infinity pool on a flat lot?
Yes, as a raised pool with the basin below the weir and the edge spilling toward a lower terrace or a planted bed. It reads as a feature wall rather than a disappearing horizon, and it is a beautiful thing in its own right.
How much more does it cost?
Meaningfully more: a second vessel, a second pump system, more engineering and far more tile. In our recent projects an infinity edge on a sloped lot sits within the estate range on our cost page. Every project is unique and custom to its environment, so the site visit decides the number.
Does the water run over the edge all the time?
Only when the edge pump runs. Most clients schedule it for the hours they are outside and let the pool sit as a still reflecting surface the rest of the day, which is its own kind of beautiful.
Tell us about the property.
We walk your property, talk through grade, access and what your jurisdiction will look for, and follow up with a written proposal setting out every line of the scope.