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Zero edge pool or negative edge pool ?

By April 7,2020 May 12th, 2021 No Comments

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For some time now, the zero edge pool, called also deck level pool, has been very fashionable; but other types of overflow should not be forgotten. There are, in fact, 4 main ones and, even if the principle of operating is more or less the same, the aesthetic effect can be very different.

The overflow in brief

When building a swimming pool, the question arises as to the usefulness of setting an overflow. It is often put forward for aesthetic reasons, but this is not its only attraction. A post about the principle of overflow can already be found in our blog but we remind you of the principle here.
In a traditional swimming pool, concrete or not, the water is sucked up by the skimmers. In the overflow pool, the water is sucked up by the pump in the balancing tank and returns to the pool after filtration and possibly heating and disinfection. Then this water in excess in the pool overflows into a gutter located below and will join by gravity the balancing tank usually located in or near the pump room. And the cycle will start all over again.

Why an overflowing swimming pool?

Most of the pollution is found on the entire surface of the water: dust, pollen, dead insects, hair and sun oil, among others.
The skimmers are the only openings to suck up the surface water and send it to the filtration system.  For a 10 x 5 swimming pool this means a maximum suction length of 1 metre (2 skimmers).
If we consider the same pool with an overflow over a length, the skimming of the surface water is multiplied by 10 and the impurities floating on the water have no time to settle onto the bottom. Imagine then the performance of  a zero edge swimming pool!
That’s why, for the same pump flow rate, the filtration of the overflow swimming pool is much more efficient.

The zero edge pool or mirror swimming pool

With its resolutely contemporary design, it is one of our favourites. Named so because it seems to “sit” on the terrace like a “mirror”, it is of great elegance. It is a peripheral overflow that exudes a very calm atmosphere.
Perfectly silent, the water overflows into the perimeter gutter covered by a grate, as is often the case in communal swimming pools. However, this grating is frequently replaced by a slot in the terrace lining through which the water reaches the gutter and then the balancing tank. This second version is undoubtedly much more aesthetic.

In the photo, a very discreet slot has replaced the traditional and ugly grating. Contrary to popular belief, this deck level pool is not limited to rectangular pools; you can see the proof here.

zero edge pool

Even if it is not noticeable at first glance and if it is sometimes unfortunately forgotten, it is necessary to note the 2 slight inverted slopes in order to avoid rainwater, dust or cleaning water from the terrace to mix with the pool water. At the same time, the pool water will not escape too much onto the terrace during untimely dives.
Usually, the water from the terrace should be collected in a specific gutter or directed towards the garden, if suitable.
In conclusion, this type of overflow is perfectly adapted to patios, flat spaces between buildings or without any particular view. And remember, it can be adapted to all pool shapes, geometric or free form.

The pool with overflow under coping

It is the oldest and is now used very rarely. It can still be seen in old swimming pools in some countries such as Morocco, Tunisia….
It was essentially designed to allow a skimming of the water surface (where the pollution is the strongest) by injecting clean water into the pool and thus discharging to the sewer the surface water that overflowed through this under coping gutter. This method, widely used in the past, represented a significant consumption of water, but it was the only way to discharge the most polluted part of the water.
It is moreover probable that the legend that runs on the high water consumption of overflow pools comes from there, since there was no balancing tank at the time. If you would like information on how the balancing tank works in an overflow swimming pool, click here.
Much less spectacular than the other types of overflow, its use is, today, often reserved for certain configurations, such as the renovation of old pools that already have such a under coping gutter or certain indoor pools. The water is, of course, not thrown down the drain, but sent to the balancing tank.

The infinity or negative edge overflow swimming pool: Spectacular

It is certainly one of the best known, because it has a fantastic aesthetic impact. It reveals all its beauty on sloping terrain, but it is possible to use it even on almost flat ground .
It often equips only one side of the pool perimeter. From the house or terrace, it gives the perfect illusion that the water disappears into nature.
The secret to the success of such an overflow is to make the gutter absolutely invisible from the terrace or the house and, above all, to make it silent and safe!  Silence is achieved by the right profile, whereas if the design is not correct, the noise of a waterfall can become infernal. Note the profile on the two attached photos, from the overflow to the house or from the house to the overflow.

negative edge pool

Specifying here that this is our favorite overflow is probably unnecessary and the various pictures you can see on our website will confirm it! And don’t forget that the sea view is not essential for such an overflow.

The zero edge pool with waterfall overflow: a luxury mix

After having explained the 3 main types of overflows: under coping overflow, infinity overflow and zero edge pool overflow, we will answer the question Can we mix several types of overflows? More and more of you are asking this question. And we can answer in the affirmative, as shown in the picture below.

zero edge infinity pool
The most frequently used combination is, of course, the infinity overflow and the deck level overflow. The visual effect of the former is combined with the atmosphere provided by the latter. Which one is your favourite? Have a look at other examples on our gallery.

The questions you may have

How to build a zero edge pool or an infinity pool?

These are of course pools to be buried, at least partially. For this type of project, a builder will offer you concrete, shotcrete or hollow blocks systems; however, some manufacturers offer pools in kits and shells. It is also possible to consider self-construction if you have detailed plans.

How much does a zero edge pool cost?

For a swimming pool with infinity overflow, it is necessary to count approximately 1,000 €/m2 of water surface; this price includes the construction of the pool, the balancing tank and the pump room as well as the necessary equipment. For a 0 edge pool, you should add about 10%.
We remind you that according to studies, the construction of a swimming pool brings from 10 to 25% of added value to a house.

Indoor or outdoor swimming pool

The deck level  pool is perfectly suited for indoor installation. It can be perfectly integrated into the layout of a space dedicated to bathing, why not by adding a spa.

Is it possible to install a roller shutter on a mirror pool?

Many manufacturers offer roller shutters to be installed in all types of infinity pools. For projects with complex shapes we often call on GRANDO Cie.

How to choose the design of an overflow swimming pool?

Deciding whether to have a zero edge pool or an infinity swimming pool is primarily a matter of taste. However, the topography of the land, the environment of the pool, its position in relation to the house, the view, etc. must be studied; in short, many parameters must be taken into account and that is our work.

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