Last updated: September 2026
Short answer: There are four pool overflow types in regular use — standard overflow, elevated overflow, perimeter (zero) overflow and Wiesbaden overflow. All four hold the water at or above the surround, take it away over the rim into a channel, and need a balance tank to work. They differ in where the channel sits, whether you can see it, how much of the surround stays usable, and whether the detail belongs in a hotel pool or should stay in a private garden.
The choice is not a finish. It is fixed on the day the reinforcement is tied, because the channel is part of the shell and the balance tank is part of the plant room. This guide sets the four pool overflow types side by side — with the tile modules, the channel bodies and the delivered pools behind them — and says plainly where each one belongs. We build custom swimming pools as a turnkey contractor, so these are the four details we detail, tile and commission ourselves.
What are the four pool overflow types, and how do they differ?
The four pool overflow types are standard, elevated, perimeter (zero) and Wiesbaden. Three of the four work in both private and commercial pools; perimeter overflow is the 1 detail our reference set restricts to private pools. The difference is the position of the channel and whether its grate is visible from the water.
Every one of them is an overflow pool in the hydraulic sense. The water surface is the working surface: it sits level with, or above, the rim, and the top layer — the layer carrying sun oil, dust and skin cells — runs continuously over the edge instead of being pulled sideways by a skimmer. What changes between the four pool overflow types is the architecture of that edge, not the principle behind it.
A skimmer pool is the other family entirely. There the water sits some centimetres below the coping and is drawn through wall-mounted skimmer throats. It is cheaper to build and it is a different product. If you are still choosing between the two families, our page on overflow and skimmer swimming pools sets out the shell and plant-room consequences of that first fork.
How does a standard overflow channel actually work?
A standard overflow is the classical detail: the pool rim finishes at deck level, the water runs over it, and a channel immediately outside the rim catches it under a removable grate. In our reference set that grate is ceramic in the same natural-stone finish as the deck, so the channel reads as 1 continuous floor.
Water leaves the channel by gravity and lands in the balance tank. From there the circulation pumps push it through the filters and the treatment train and return it to the pool floor and walls. Nothing about that loop is decorative: the channel is the intake for the whole system, and if it is undersized or badly fallen, the filtration behind it never sees the surface layer it was bought to clean.
The grate is the part people touch. It is walked on barefoot, it is lifted for cleaning, and it has to sit flush enough that nobody catches a toe. Our standard overflow sheet carries 13 ceramic formats for exactly this reason, including 6 × 60 cm and 6 × 50 cm channel-edge strips and a 25 × 12.5 cm coping piece with a 12 mm radius on the nose.
Where does a standard overflow belong in a project?
Standard overflow belongs anywhere the pool has to absorb a crowd. It is the only 1 of the four pool overflow types whose channel capacity is openly visible and easy to service, which is why it carries most hotel, club and school work. Our reference set marks it usable in both private and commercial pools.
Bather load is the reason. When 20 people enter a pool at once, the volume they displace has to go somewhere in seconds, and the channel is the only route. A wide channel under a liftable grate gives the surge a fast, inspectable path. A narrow slot does not, which is where the other pool overflow types start to have opinions about who is allowed to swim.
It is also the detail that survives ordinary maintenance. Grates come up, the channel gets brushed, leaves come out. In an indoor swimming pool that matters less; in an outdoor pool under trees it decides how the pool looks by August.
What makes an elevated overflow different from a standard one?
An elevated overflow raises all 4 sides of the pool above the surrounding deck. The water spills over the raised rim, falls down the outside face and lands in a recessed channel at deck level. From inside the water you see no edge at all; from outside, the pool reads as an ornamental basin standing proud of the floor.
The document that defines our four pool overflow types puts it plainly: all sides of the pool are elevated relative to the surround, which gives an infinite pool effect for the person in the water and an ornamental look for everyone else. It is cleared for both private and commercial use. What it asks for in return is a deck that can be dropped, because the channel now sits below the finished floor on every side.
Tiling changes too. The raised face is a visible elevation, not a hidden edge, so the reference sheet carries narrow rim strips at 7 × 60 cm and 7 × 75 cm alongside large deck formats at 60 × 120 cm and 75 × 75 cm. Fourteen formats in total — the widest palette of the four, because there is simply more surface on show.
Is an elevated overflow the same thing as an infinity pool?
No. An infinity pool spills over 1 side only, and it needs a view and a level drop beyond that side to hide the catch basin. An elevated overflow gives the same edgeless reading on all four sides, on flat ground, with no borrowed landscape. They solve the same perception problem by opposite means.
That distinction matters on a flat plot. Architects often arrive asking for a vanishing edge because it is the image they have seen, then discover the site has nothing to vanish into. An elevated overflow answers the same brief without the topography, and it does it on every elevation rather than one. Where the site genuinely does fall away, a true infinity pool is still the stronger move.
There is a maintenance difference as well. A vanishing edge concentrates the whole overflow onto one wall, so that wall’s level tolerance and its catch basin do all the work. An elevated overflow spreads the same duty around the full perimeter, which is gentler hydraulically and less forgiving geometrically.
Why is perimeter (zero) overflow restricted to private pools?
Perimeter overflow, also called zero overflow, has no channel grate on the surface at all. The water reads as a sheet of glass finishing flush against the stone. Our reference set clears it for private pools only — the 1 restriction among the four pool overflow types — because everything that makes it beautiful also makes it intolerant.
Two things drive the limit. First, capacity: the whole overflow has to pass through a slot you are not allowed to see, so there is no room to oversize the opening when bather numbers rise. Second, tolerance: with no grate to visually break the line, any deviation in the rim level shows up immediately as water standing on one side and a dry edge on the other.
That is a fair trade in a villa garden, where the pool is used by a household and the picture is the point. It is a poor trade in a hotel, where 30 guests can arrive together and the pool has to keep working while the surface is disturbed. For a commercial brief we would steer the same client towards a standard or Wiesbaden detail.
What does a perimeter overflow ask of the structure and the deck?
It asks for a rim that stays level all the way round and a deck that drains away from the slot rather than into it. Our reference sheet offers perimeter overflow in only 6 ceramic formats, running from 60 × 120 cm down to mosaic, because every extra joint is one more chance for the line to wander.
The 6 formats are 60 × 60 cm, 60 × 60 × 2 cm, 60 × 120 cm, 30 × 60 cm, 15 × 15 cm and 5 × 5 cm mosaic. Large formats are the point, not a style preference. A 60 × 120 cm porcelain unit gives you 120 cm of straight, factory-flat edge at a time; a mosaic gives you 5 cm. On a 12 m pool that is the difference between ten setting-out decisions per side and two hundred. The perimeter detail is the one place where tile size is a structural argument.
Below the tile, the shell has to be poured and given its full curing time before the rim is set, and the slot has to fall continuously to its outlets. None of this is exotic. It is simply work that cannot be corrected later, which is why the perimeter detail has to be chosen before the shell, not after the client has seen a photograph.
What is a Wiesbaden overflow, and what makes its channel different?
A Wiesbaden overflow starts the spill on the pool border itself and carries it in a pre-formed ceramic channel body, with a ceramic grate laid on top. It is the only 1 of the four pool overflow types whose channel arrives as a manufactured component rather than being formed in concrete on site.
The name belongs to German pool vocabulary, where the Wiesbadener Rinne describes this detail; Wiesbaden is a spa city in Hessen with a long thermal bathing history. The practical gain is surround: because the channel body sits immediately at the pool border and carries its own cover, the usable deck starts sooner and the pool reads wider. Our reference set clears it for private and commercial pools alike.
The components are dimensioned rather than described. Grate covers come in 25 × 50 cm and 30 × 30 cm, the 30 × 30 including two mitred corner pieces so the channel turns a corner without a site cut. The channel bodies beneath them carry hard millimetre figures — 295 across the module, 138 through the internal throat, and 194, 244 and 119 on the three body profiles drawn.
How do the four pool overflow types compare side by side?
Side by side, the 4 details separate on three questions: where the channel sits, whether its grate is visible, and who is allowed to use the pool. The table below is taken from our own concept pool design reference set, which defines each type and states its permitted use in 1 line each.
| Overflow type | Where the channel sits | Grate visible? | Permitted use | Ceramic formats in our set |
|---|---|---|---|---|
| Standard overflow | Outside the rim, at deck level | Yes, flush with the deck | Private and commercial | 13 |
| Elevated overflow | Below deck level, outside a raised rim | Recessed, read as a shadow gap | Private and commercial | 14 |
| Perimeter (zero) overflow | Behind a narrow slot at the stone line | No | Private only | 6 |
| Wiesbaden overflow | On the pool border, in a ceramic channel body | Yes, ceramic cover on the body | Private and commercial | 3 grate formats |
Read the last column as a design instruction rather than a stock list. The perimeter sheet is short because the detail wants long, flat units and punishes joints. The elevated sheet is long because the raised face is on show from the garden and has to be composed like a wall, not a floor.
Which standards govern the overflow channel?
Three documents do most of the work. DIN 19643-1, released in 2023 and running to 74 pages, sets the general requirements for treating swimming pool water. EN 15288-1:2018 covers safety in design. National law then adds its own layer.
Turkey’s swimming pool health regulation is unusually direct about the channel. Published in the Official Gazette on 6 March 2011 under number 27866, its Article 4 defines a swimming pool as a structure whose floor, walls, overflow channels and reserve tank are lined in material that does not affect water quality — and which has a continuous recirculation flow. The channel is not an accessory in that definition. It is part of what the word “pool” means.
The same article defines turnover time as the period needed for the total pool volume to pass once through the filtration system, and Article 8 requires the pool to be emptied and generally cleaned at least once a year. Those two clauses are worth reading together with your chosen overflow detail, because a channel you cannot lift a grate off is a channel you will be cleaning the hard way. The European standards themselves reach Turkish projects through the Turkish Standards Institution catalogue, which is where a specification should name them.
Why does every overflow pool need a balance tank?
Because the pool has no freeboard. With the water sitting at the rim, there is nowhere inside the pool for displaced volume to go, so a buried tank holds the difference. All 4 pool overflow types are deck-level systems in this sense, and all 4 need one; a skimmer pool does not.
The UK Pool Water Treatment Advisory Group puts the requirement without qualification in Technical Note TN32: on any deck-level system a balance tank will be incorporated to ensure that the pool water remains at the optimum level for effective surface water removal under all operating conditions. Read that backwards and it explains most overflow failures. If the level is wrong, the surface is not being removed, and the treatment plant is filtering the wrong water.
Three loads decide the tank: the volume bathers displace at the busiest moment, the volume held in the channel and pipework itself, and the volume a filter backwash takes out of circulation. Get it wrong in the small direction and the pool sucks air. Get it wrong in the large direction and you have paid for a concrete room nobody needed.
How does tile format decide what the overflow edge can look like?
Tile format is the hidden constraint in all 4 pool overflow types. The edge is built from manufactured units, so the smallest change you can make to its geometry is 1 unit wide. That is why our reference sheets list formats rather than adjectives: 60 × 120 cm behaves nothing like 5 × 5 cm mosaic at a rim.
Mosaic still has a job. A 5 × 5 cm sheet on a 297 × 297 mm backing bends around a curve that a large porcelain unit cannot approach, which is why the elevated and standard sheets both carry it. It simply should not be carrying the visible level line of a perimeter overflow, where every one of those joints is a chance to lose the plane.
The channel itself is the sharper example. A Wiesbaden channel body arrives at fixed dimensions and the grate is made to sit on it; a site-formed concrete channel is whatever the formwork gave you, and the grate then has to be cut to fit. Deciding that early is a tiling decision that turns into a programme decision.
Which delivered pools stand behind these four details?
Between 2020 and 2025 we built the swimming pools at 17 named hotels, along with public, school and residential pools across several countries. That work is what the four pool overflow types are drawn from: a reference set written by a contractor who has had to build all 4 of them, not a catalogue assembled from images.
On the hotel side we built the pools at the One&Only Portonovi in Montenegro, the Four Seasons and Port Baku in Azerbaijan, the Hyatt Regency in İzmir, the Hilton Bomonti, the Dusit Thani Maslak, the Pera Tulip Şişhane and the Yeşilköy Holiday Inn in Istanbul, the Sheraton and the Radisson Blu in Batumi, Hillside Su and Club Salima in Antalya, and the KBF Hotel in Algiers.
On the facility side the list runs to the Heybeliada Olympic swimming pool and the İstinye Park decorative pool in Istanbul, the Presidential Complex indoor pool in Ankara, the State Palace pool in Dushanbe, the Aktau pool complex in Kazakhstan, Yeditepe University’s outdoor pool, and 8 İstek Foundation school campuses. On the residential side, the Tahincioğlu Nidapark indoor pool in Sarıyer and private pools in Tashkent and Girne.
Two honest caveats. Naming a hotel says we built its pool; it is not an endorsement, and we do not use anyone’s marks. And our reference document records the projects and the four details separately — it does not record which detail went into which pool, so we do not claim that here. For the commercial side of this work, see how we approach commercial spa projects.
What goes wrong when the overflow type is decided too late?
Three things, in this order. The shell is already poured to the wrong rim geometry. The plant room was sized without a balance tank, or with one 2 sizes too small. And the deck falls run towards a channel that has since moved. Each of those is concrete work, and concrete work is the expensive kind to revisit.
The pattern is familiar on fast programmes. A shell goes in early to unlock the landscape trades, the interior designer arrives later with a perimeter overflow in the mood board, and the rim that was built to sit 30 mm proud now has to finish flush against stone that was never set out for it. Nobody did anything foolish; the decision simply happened after the deadline it belonged to.
The fix is calendar, not technique. Fix the overflow detail at concept stage, alongside the shell type, and let the tile module and the balance tank follow from it. On an outdoor swimming pool the same rule applies to the deck falls, which have to be drawn before the paving is ordered.
How should you choose between the four pool overflow types?
Answer 3 questions in order. Is the pool private or commercial? If commercial, perimeter overflow is out and you are choosing between the other 3. Does the surround need to be as wide as possible? That points at Wiesbaden. Do you want an edgeless reading on every side without a level drop? That is elevated overflow.
If none of those pull hard, build a standard overflow. It has the largest serviceable channel, the widest tiling palette after elevated, and the fewest ways to go wrong in the second year of operation. It is the detail we specify when the brief is a working pool rather than a photograph, and it is behind most of the commercial work above.
What we will not do is pick the detail from a rendering. The right answer depends on the bather load, the deck level you can achieve, the plant room you have and the tile module you can source — and those are four site facts, not preferences. Send us the plan and the level survey and we will tell you which of the four pool overflow types the site will actually carry. Talk to our pool design team before the shell drawings are issued.
Who is writing this
Sauna Dekor has been building wellness and water facilities since 1987 and is now in its 40th year, manufacturing in its own Istanbul facility with a team of 19 and working under TS EN ISO 9001:2015, with projects delivered in more than 35 countries. On pools we work turnkey: shell, waterproofing, equipment package, installation and commissioning.
What we do not do is equally clear. We do not manufacture the circulation pumps, the filters, the dosing equipment or the underwater lighting. Those come from the equipment manufacturers we buy from and work alongside — AQUA Industrial Group, DAB Water Technology, Behncke, Hugo Lahme and Oase among them — and any certification on that equipment belongs to its manufacturer, not to us. The TS EN ISO 9001:2015 certificate is ours; the rest are theirs.
Frequently asked questions about pool overflow types
Can a skimmer pool be converted into an overflow pool?
Rarely without rebuilding the rim. The conversion needs a channel around the pool, a balance tank, and a raised water line, which together touch the shell, the deck and the plant room. On most existing pools the honest answer is a new shell rather than a conversion.
Which of the four overflow details is simplest to build?
Standard overflow, by a clear margin. The channel is formed with the shell, the grate is a manufactured ceramic unit, and the level tolerance is forgiving because the grate visually breaks the line. Perimeter overflow is the demanding end of the same idea.
Does an overflow pool use more water than a skimmer pool?
It holds more, because the balance tank is filled as well as the pool, but it does not necessarily lose more. Evaporation depends on surface area, temperature and air movement rather than on the edge detail you chose.
How wide is a pool overflow channel?
It follows from the grate module and the flow the channel has to carry, not from a fixed rule. In our reference set the visible width is set by ceramic covers at 25 × 50 cm and 30 × 30 cm, and by channel bodies dimensioned in millimetres beneath them.
Can a perimeter overflow go into a hotel pool?
Our reference set clears perimeter overflow for private pools only. The slot cannot be oversized without becoming visible, so it has little margin when a group of guests enters together. For hotel work we specify standard or Wiesbaden instead.
Does an indoor pool need a different overflow detail?
The detail is the same; the surround changes. Indoors there are no leaves to trap but there is condensation and constant humidity, so grate liftability and channel drainage matter more than they do outside, and the deck material has to stay safe when permanently damp.
Sources
- DIN 19643-1, Treatment of water of swimming pools and baths — Part 1: General requirements, released 2023-06, 74 pages.
- BS EN 15288-1:2018, Swimming pools for public use — Safety requirements for design, published 12 December 2018.
- Türk Standardları Enstitüsü, standard catalogue search, where the Turkish adoptions of the European pool standards are listed.
- Pool Water Treatment Advisory Group, Technical Note TN32: Balance tank design for deck-level pools, January 2016.
- Pool Water Treatment Advisory Group, Code of Practice, the UK reference for pool water treatment and circulation.
- World Health Organization, Guidelines for safe recreational water environments, Volume 2: Swimming pools and similar environments, 2006, ISBN 92 4 154680 8.
