PVC Accessories

When we talk about hydraulic installations in swimming pools, one of the key elements to ensure a good performance of the filtration and purification system is the diameter of the PVC pipe. Choosing the right size not only affects the performance of the pump, but also the energy efficiency and durability of the system.

Most common sizes for private pools

In standard size residential pools, i.e. those with an approximate volume of up to 60-70 m³, the most common size is:

Ø50 mm (1½ inch) PVC pipe

This diameter is sufficient to handle normal filtration and return flows, without significant head loss or choking.

Larger capacity pools

When dealing with larger pools, for example, between 80 and 100 m³, it is advisable to opt for a larger diameter:

Ø63 mm (2 inch) PVC pipe

This increase in diameter makes it possible to maintain an adequate flow without overloading the pump, avoiding noise, vibrations or excessive pressure in the installation.

when to increase the diameter even more?

In larger installations, such as community or semi-Olympic pools, larger diameters can be used:

• Ø75 mm (2½ inches)
• Ø90 mm (3 inches)
• Ø110 mm (4 inches)

These sections are chosen based on technical calculations of flow rate, length of the installation, number of hydraulic elements (nozzles, skimmers, sumps, etc.) and maximum water speed recommended to avoid noise or cavitation.

Additional considerations

• The water velocity in suction pipes should not exceed 1.5 m/s, and in discharge pipes, 2 m/s. Exceeding these limits can generate noise and efficiency losses.
• Using an insufficient diameter is a common mistake in old or poorly designed installations, causing problems such as excessive pressure, pump wear or poor filtration.
• In installations with variable speed pumps, choosing the right diameter helps to maximize efficiency in low flow cycles.

One of the fundamental aspects to take into account when designing or maintaining a hydraulic installation in swimming pools is the pressure that PVC pipes and fittings must withstand. Although the working pressure in a swimming pool is relatively low, materials with very wide safety margins are used, both for durability and for technical and regulatory requirements.

Typical working pressure in a swimming pool

In most private pools, the operating pressure of the filtration system is usually around 0.8 bar (approximately 0.8 atmospheres).

This pressure is mainly generated by the pump when pumping water through the filter and the return circuit.

For hydraulic installations in swimming pools, pressurized PVC pipe, also known as pressurized PVC (PVC-P), is commonly used. The use of non-pressurized PVC is not recommended under any circumstances, since it is not designed to withstand the hydraulic loads and mechanical stresses of the ground when the pipe is buried.

Classification by nominal pressure (PN)

PVC pipes and fittings are classified according to their nominal pressure (PN), which indicates the maximum pressure they can withstand at 20°C continuously. The most common in swimming pools are:

• PN 8: Withstands up to 8 bar pressure
• PN 10: Pressure rating up to 10 bar

Both options are more than sufficient for domestic installations, since they offer a very wide safety margin with respect to the real working pressure.

what about fittings (elbows, tees, sleeves, etc.)?

PVC fittings (elbows, tees, unions, etc.) are usually made of PVC-U (non-plasticized rigid PVC) with even higher ratings:

• PN 16: They withstand up to 16 bar pressure

This guarantees the structural safety of the installation, even under demanding conditions, such as vacuum filling, water hammer or soil deformation.

PVC fittings for swimming pools must comply with specific standards to ensure their quality and safety.

In Europe and Espa, the most relevant standard is UNE-EN ISO 1452, which regulates PVC piping systems for water conduction and sanitation under pressure.

This standard covers various technical and manufacturing aspects, especially in Part 3: Fittings, which establishes the requirements to be met by these parts.

In addition, it is advisable that the fittings have quality certifications such as AENOR, which guarantees compliance with current standards. These certifications are a guarantee that the products have passed rigorous technical controls and offer safety, durability and compatibility with existing systems.