ConstructionSantorini

F-12 · External works

Swimming pool construction

On a caldera plot, a pool is a retaining structure that happens to hold water.

Short answer

A pool on a Santorini slope is a structural problem before it is a leisure one: it retains ground on one side and holds water on the other, which makes it an engineered structure. Water supply, evaporation in summer wind and plant room siting are the three practical constraints owners underestimate.

What to expect

Typical duration8–20 weeks depending on structure and access
Cost bandFigures live in the cost index
Permit requiredYes — structure, and often drainage and water supply too
Seasonal constraintBuild in the closed season for a summer opening

The structure comes first

On a flat inland plot a pool is a tank in the ground. On a Santorini slope — which is most of the interesting sites — it is a retaining structure holding back the hillside on the upslope side while holding water against a face that may be partly free-standing on the downslope side.

That combination has to be engineered. Ground conditions, drainage behind the structure, and what happens to the hillside when you remove several hundred cubic metres of it are all part of the design, and none of them is a pool-builder's decision.

free-draining backfill behind the full height weep holes at 1.5–2 m centres perforated land drain to daylight winter rain reaches the back of the wall pressure builds from the bottom up so the drain sits at the bottom batter — the face leans into the slope retained height Above roughly 1.5 m of retained height a wall stops being landscaping and becomes a structure that needs an engineer.
A-05 Terrace wall on volcanic ground. Almost every failure on the island is water, not load — the wall was built to hold soil and never given a way to let water out.

Infinity edges — which is what almost everyone wants on a caldera plot — add a balance tank, a higher pumping duty and a considerably less forgiving structural tolerance, because the edge only works if it is genuinely level.

Where the water comes from, and where it goes

  • Filling. There is no assumption of an adequate network supply for a pool here. Filling is frequently by tanker, or from a desalinated supply, and both need planning rather than a hose.
  • Evaporation. Open water plus summer heat plus persistent wind produces meaningful losses. A cover is not a luxury item on this island — it is how you avoid topping up by tanker repeatedly through August.
  • Backwash and emptying. Where the discharge goes is a real question on a property without network drainage, and it interacts with the permit. It gets designed, not improvised.
  • Rain. Winter runoff from surrounding terraces into a pool area needs routing, or the pool becomes the drain for the whole terrace.

Plant room, the item that gets forgotten

Pool plant needs a location that is ventilated, drained, accessible for service, electrically safe and — in a designated settlement — not visible. On a compact caldera plot that is a genuinely difficult set of requirements and it has to be solved in the design, not found afterwards.

Noise matters too. A pump running under a bedroom, or against a neighbour's wall in a dense settlement, becomes a dispute. Siting and isolation are cheap at design stage.

Materials and finishes in this environment

  • Coping and surround stone chosen for a surface people walk on barefoot in full sun. Some visually appealing dark stones become unusable in July.
  • Fixings, ladders, handrails and light housings in A316 stainless. Anything less will stain the coping and seize within a few seasons.
  • Tile or finish specified for salt, chlorine and UV together, which narrows the field considerably.
  • Movement provision between the pool structure and the surrounding terrace, because they will move differently.
Thin cover — 15 mm Correct cover + grade for XS3 15 Chloride reaches the bar. The bar expands. The cover spalls. Two to six years on an exposed elevation. Repair cost: cut out, passivate, re-form, re-finish — many times the cost of the cover. cover to code low-permeability mix + protective coating to the exposed face Cover, mix design and stainless fixings are specified together. Getting one of the three right is not a specification. A316 stainless at every anchor, balustrade base and hidden fixing within reach of spray.
A-04 Corrosion of embedded reinforcement. Rust occupies several times the volume of the steel it came from, so the concrete is pushed off from the inside — the crack is the symptom, the cover was the cause.

Questions people actually ask

How long does a pool take to build?

Eight to twenty weeks, driven mostly by structure and access. A pool on a flat plot with vehicle access is at the fast end; a structural pool on a caldera slope with hand-carried material is at the slow end and beyond.

Do I need a permit for a pool?

Yes. It is a structure, it usually involves excavation and retention, and the water supply and discharge arrangements form part of the application. In a designated settlement its visibility is also considered.

Can I have an infinity edge?

On a suitable plot, yes — and it is a more demanding build: a balance tank, higher pumping duty, and a genuinely level edge with very little tolerance. It is worth budgeting for properly rather than adding late.

How much does it cost to fill and run?

Filling depends on your water source and volume, and running cost is dominated by pumping and heating. Evaporation losses in a windy August are real — a cover changes the arithmetic substantially. Bands are in the cost index.

Can you build a pool on a small caldera plot?

Frequently yes, though it may be a plunge pool rather than a swimming pool once setbacks, structure and plant space are accounted for. We would rather tell you that at the start than design something that will not fit.

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