For their beauty and elegance, infinity pools have long been a dream. Often, they can be considered the jewels of the garden due to their fusion with their surroundings. Unfortunately, their technical qualities frequently remain unnoticed. Knowing how an infinity pool filtration system works will help you better understand why water quality is significantly improved.

How Does An Infinity Pool Filtration Unit Work?

A swimming pool’s water filtration is made up of two elements: the hydraulic circuit, which filters the water, and the equipment installed in the plant room.

The circulation of the water in the overflow pool

In a regular swimming pool, the filtration pump draws water into the pool through the skimmers. The water is then sent to the filter tank and returns to the pool after passing through any heater and water treatment.

There are two types of overflow pools: a pool where water spills over the side, known as an infinity pool, and a pool around an edge, known as a zero-edge pool. The vanishing water from the pool reaches a gutter below; it flows by gravity into a nearby balance tank. Pumps draw water through a drain embedded in the bottom of the balance tank. The water passes through the filter unit and returns to the pool through the inlets.

plan piscine
Infinity pool piping layout drawing designed by Morana Water Design

By looking at a plan of an overflow pool, it is easier to grasp how this works. You can see the flow of water into the balance tank, the suction (out of the pool), and the return (back into the pool).

What’s In The Plant Room?

The basic plant room of an overflow pool isn’t that different from a pool with skimmers. Besides the pump and filter that make up the filtration unit, there are also:

  • A system to regulate the water level in a catch basin based on factors such as the number of bathers in the pool, evaporation, or rain.
  • More safety valves and check valves are required.

For clean water, use the overflow principle

A negative edge pool and a zero edge pool use reverse flow technology to keep the water cleaner and clearer. The filtration system and water treatment assist in this process.

An overflow pool's hydraulic circuit plays a big role in water maintenance

It is the overflow pool principle that helps keep the pool water cleaner and clearer, but the filtration system and water treatment also assist. An infinity or zero deck pool’s hydraulic system plays a critical role in water quality maintenance. The principle of an overflowing pool allows a complete skimming of the water surface. This is not the case for a regular pool. We recall that impurities, including sunscreen residue, insects, and plant debris are found on the surface. Additionally, the inlets embedded in the pool ground ensure better mixing of chemical products and prevent dirt buildup. This makes pool maintenance easier.

Get the drawings you need for your pool filter installation.

Morana's advice 👇

Don’t oversize the filter unit

An oversized filter unit may seem like a good idea for better filtration, but it can actually lead to higher energy consumption and increased maintenance expenses. A properly sized filter unit, on the other hand, provides efficient filtration and saves on both upfront and long-term expenses.

Plan for the future

Depending on the size of your budget, you may not be able to consider all the options when building your swimming pool. Ensure that future installations will be possible.

But what is the filtration unit for?

Pumps and filters work together to maintain the water quality in an overflow pool, just as they do in a pool with a skimmer. The first one sucks water into itself and sends it back into the pool. Meanwhile, the second one retains impurities. Filters are classified by filtration fineness expressed in microns, such as sand filters or that contain recycled glass, cartridge filters, or diatomaceous earth filters.

Note: There is a pressure gauge on the sand filter. This controls how clogged the filter gets and how well it can filter the pool water. Keep the needle in green at all times.

Water is disinfected either manually with chlorine tablets or automatically with equipment in the plant room. The goal is to prevent the growth of algae, bacteria, germs, and fungi in the water and on the walls of the infinity pool.

If you plan to build your own top level or infinity pool, getting expert advice is definitely worthwhile.


The Filtration Unit For An Infinity Pool Is Generally Quite Complex

A properly designed hydraulic system and equipment installation in the plant room are vital when building an overflow pool. With the pool design as a guide, one can determine the locations of the drains and inlets, as well as how the piping leads to the filtration unit. If you place each valve and device in the right place, you’ll avoid pipes crossing and pressure losses.

Design of the overflow channel and the balance tank can be tricky if you want to construct a pool yourself. If it is a negative edge pool, the gutter can sometimes be used as a balance tank. A catch basin will need to be built next to the plant room if it’s a zero edge pool.

In What Ways Does Morana Water Design Help Define Your Filtration System?

It is your choice whether to build your pool yourself or to hire a pool builder. At least in the first case, having an overflow pool designer on hand is useful.

Select the appropriate filtration unit

Our experts recommend the right filtration system for your pool based on the number of people using it, its size and the water quality. The balance tank is sized appropriately to save you money. A second pump for the overflow or a large filter can often be avoided, as they are often unnecessary.

How to get hydraulic layouts

Based on the pool general plan, Morana Water Design produces the plumbing drawing and the layout for the filtration system and optional equipment installation in the plant room. You can have a plumber who isn’t an expert on overflow pools install the filtration system.


Filtration systems for infinity pools or deck-level pools are not necessarily difficult to install, but they cannot be installed randomly. Professional drawings allow you to plan the placement of equipment, valves, and the pipe routing. It is not uncommon to find equipment rooms with crisscrossing pipes, which makes it difficult to access valves or repair them. By having a plan prepared by experts, you will be able to avoid this problem and ensure the performance and maintenance of the pool are optimized.