One-side overflow: water at the edge on one side only

How it works

In a perimeter overflow pool, the water spills over on all sides into a channel covered by a grating about 25 cm wide, collects in a balance tank, is filtered and returns. A one-side overflow follows the same logic, except that the channel and grating are on one side only. On the other sides the edge sits slightly above the water, as in a skimmer pool.

The result is a pool that looks like a mirror at floor level from one angle, while from the others it has a clean, visible edge. For the basics of the perimeter option, see overflow channel pools.

The grating on the overflow side can be plastic or marble, to tie in with the paving; the differences are explained in the overflow grating. On plots with a difference in level, there is also a variation where the water falls into a channel below the edge, so that no edge is visible from the terrace at all. It is a more demanding solution and depends on the ground levels.

Compared with a perimeter overflow

The balance tank is not left out just because the overflow is on one side only. The water that swimmers displace as they get in has to go somewhere, and that depends on how many there are, not on the length of the channel.

When it suits

• A pool with a view. The overflow side faces the sea or the valley, and the water seems to merge with the landscape.
• A sloping plot. The downhill side is a natural place for an overflow. See also a pool on a sloping plot.
• A pool next to the house. The side facing the living room or terrace becomes a mirror, while the sides facing the garden stay simple.
• A pool close to a wall or boundary. Where there is no room for a grating all the way round.

When the pool is large and many people will use it at once, as at a holiday rental, a perimeter overflow usually keeps the surface cleaner. For a simple family pool with no particular view, a skimmer pool remains the simplest solution.

What to watch for

1. The wind. If the prevailing wind pushes leaves and dust towards the overflow side, the cleaning almost takes care of itself. If it blows the other way, debris collects along the other sides.
2. The position of the inlets. The return inlets are placed so that they push the surface towards the channel. See the role of each fitting in pool inlets and fittings.
3. The levels. The edge on the overflow side must be perfectly level, otherwise the water spills over at one point only.
4. The transition at the corners. This is where the channel meets the raised edge, and the detailing decides the final look.

The feasibility of a one-side overflow, the position of the tank and the levels are checked for each plot at the site survey.

Questions

See also