Water Pressure-Reducing Valve: What It Is, How It Works, and How to Choose One

The water pressure from the public water supply is not always adequate for the systems it serves. When it is too high or unstable, leaks, noise, water hammer, and malfunctions in faucets, water heaters, and industrial equipment can occur.

A water pressure-reducing valve is the component that solves this problem: it reduces the inlet pressure to a stable and safe level, regardless of fluctuations in the water supply. In this guide, we explain what it is, how it works, how to install and adjust it, and what criteria to follow when choosing the right model.

A pressure-reducing valve (PRV) is a mechanical device that reduces the pressure of a fluid as it passes through and maintains a constant pressure downstream at the set value. In the case of water, it protects the entire system downstream from excessive pressure from the water supply network.

Its function is to convert high and variable inlet pressure into lower and more stable outlet pressure. Unlike a simple shut-off valve, which only opens or closes, the pressure-reducing valve regulates automatically and continuously: it responds to changes in consumption and network pressure to maintain the set point.

Thus, even if the inlet pressure rises at night or fluctuates throughout the day, the pressure reaching faucets, appliances, and equipment remains within the desired range.

Table of contents

Excessively high water pressure accelerates wear and tear on the entire system and increases water consumption. The most common consequences are:

Reducing and stabilizing pressure extends the system’s service life, improves comfort, and reduces maintenance costs.

Water pressure-reducing valves are used in a wide variety of settings. In domestic and residential settings, they protect homes, apartment complexes, and buildings from high water supply pressure, especially on the ground floors of tall buildings, where the water column pressure is higher.

In the commercial and service sectors, they are installed in hotels, hospitals, sports centers, and office buildings, where stable pressure ensures comfort and the proper operation of the equipment.

In the industrial sector,they regulate process circuits, cooling systems, demineralized water lines, and applications that require special materials or oxygen service. In all cases, the principle is the same: to deliver a controlled and constant pressure to the point of use, regardless of variations in the supply network.

Understanding how it works helps you install and adjust it properly, and troubleshoot problems when they arise.

Most direct-acting water pressure reducers operate based on the balance between fluid pressure and spring force. Inlet pressure reaches the valve, which closes due to the difference in cross-sectional area. When the spring is compressed using the adjustment screw, the shaft-closing assembly opens the passage and allows the outlet pressure to be regulated.

When the downstream pressure exceeds the set value —for example, when the load is shut off— the valve closes automatically; when demand resumes, it reopens. In self-compensating piston models, this design ensures a particularly stable outlet pressure even when the inlet pressure fluctuates. If you’d like more information on how to represent this component in drawings and installations, please refer to our guide to pressure-reducing valve symbols.

It is important to distinguish between two main types. Direct-acting pressure reducers, such as the one described in this article, are simple, reliable, and economical, making them ideal for most water systems. Pilot-operated pressure-reducing valves incorporate a pilot valve that improves accuracy at high flow rates or with high pressure drops, though they are more complex. For residential, commercial, and most industrial applications, a self-compensating direct-acting pressure-reducing valve more than meets the needs.

The pressure-reducing valve is installed on the water supply line, after the meter and the main shut-off valve, so that it protects the entire downstream system. The adjustment screw should be left accessible, and, whenever possible, a pressure gauge should be installed downstream to check the outlet pressure.

As a general rule, it is recommended to install a shut-off valve before and after the main valve to facilitate maintenance without draining the entire line. Many models, such as those from Valfonta, can be installed in various positions and allow access to the mechanism without disconnecting the supply line, which greatly simplifies their installation and inspection.

Adjustment is performed with the valve in service and the outlet partially open, by turning the adjustment screw: compressing the spring increases the outlet pressure, and loosening it decreases it.

The optimal pressure depends on the application, but in domestic water systems it is typically between 2.5 and 3.5 bar, without exceeding the 5 bar limit set by building codes for the point of use.

After making the adjustment, check the reading with a pressure gauge and verify that the pressure remains stable both during use and when idle. You can find more information in our articles on how to adjust a pressure-reducing valve and where to install a pressure-reducing valve.

Related articles:

Not all gear reducers are suitable for every installation. Making the right choice requires evaluating the operating conditions and the equipment’s performance.

Before deciding on a model, it’s a good idea to be clear about the following factors:

When in doubt, the safest approach is to seek advice from a manufacturer who can evaluate the system and recommend the valve that best meets each specific need.

The Valfonta PRV30 pressure-reducing valve is a direct-acting, self-compensating piston-type pressure reducer designed to maintain a stable outlet pressure even in the face of fluctuations in the supply network. It is easy to install, requires little maintenance, can be mounted in multiple positions, and allows access to the mechanism without disconnecting the supply line, offering highly reliable regulation. Its main features are:

In addition, the PRV30 can be configured on demand with additional features:

You can view the complete product specifications at PRV30 pressure-reducing valve or view the entire product line in the pressure-reducing valves.

Do you need help choosing your water pressure-reducing valve? Email us at valfonta@valfonta.com or call 933 720 888 and our technical team will assess your installation.