If you’re specifying, installing, or upgrading pipework for a potable (drinking) water system, the question “What’s the best valve for potable water applications?” will be an important consideration.
With safety, durability, and compliance with New Zealand’s stringent water quality standards at stake, informed choices are essential. This article answers the top five questions professionals should ask when making a valving selection.
1. Why does valve selection matter in New Zealand potable water systems?
Valves control your piping system, directing and regulating flow, isolating pipework, controlling pressure, releasing air, preventing backflow, and managing temperature are some of the critical functions valving performs ensuring the operational efficiency and durability of a potable water system. and ensuring water runs where (and how) it’s meant to. In Aotearoa, our drinking water standards and standards for products suitable to drinking water applications, such as Watermark, are designed to maintain quality and protect public health.
The wrong valve material or non-compliant product can put public health and the long-term durability of a system at risk through such things as leaching, bacterial growth, or premature failure. Choosing approved and certified, fit-for-purpose valves is not just best practice; it’s requirement. .
2. What common valve types are used for potable water systems in NZ, and how do they compare?
Every valve has its own functional advantages and disadvantages which must be considered. Professionals most often encounter and select from these categories:
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Ball valves:
Highly popular as an isolation valve due to their reliable on/off control, minimal leak risk, and ease of maintenance, particularly those with a union, flange, or 3-piece construction. Common materials include brass (DZR/DR - dezincification-resistant), stainless steel, or approved plastics for potable water systems. Their quarter-turn operation and clear open/close indication are especially useful in residential, commercial, and municipal settings.
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Gate valves:
Also commonly used as an isolation valve, their full-bore design minimises pressure loss and maintains full flow through the valve. They are slower to operate requiring several turns to open or close the valve, however slower operation can have the benefit of minimising or eliminating factors such as hydraulic shock, commonly known as ‘water hammer’. Outside of flanged connections on larger gate valves, there are less options with this type of valve for creating a disconnection or disassembly point around or on the valve for ongoing maintenance.
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Butterfly valves:
Most commonly used more in commercial, municipal, or industrial applications and on larger pipelines, typically from 65mm (2 ½") and up. They offer easy operation and with the notch plates can provide some measure of flow control although these valves are typically recommended as an isolation valve rather than a regulating valve. The fast operation can be a cause for water hammer however this can be mitigated using gearbox operator control or electric actuation rather than lever handle operation. Having a relatively narrow width can also be an advantage for this type of valve particularly in tight spaces such as plantrooms.
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Check valves:
Also commonly referred to as ‘Non-return’ or ‘One-way’ valves, they are designed to prevent backflow and water contamination, an essential component in many pipelines. They are commonly available in spring, swing, or ball type options, in a variety of different materials, and typically with flanged or threaded connections.
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Globe valves:
These are commonly used for regulating flow as they. offer incremental and precise control but are less common in straightforward isolation scenarios.
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Pressure reducing and air-release valves:
Crucial for managing pressure surges, water hammer, and air pockets, protecting system integrity and user safety.
3. What valve materials are safe and approved for NZ drinking water?
Not all materials are created equal. NZ Building Code and Council standards require:
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Brass:
Only use dezincification-resistant brass (DZR/DR). General purpose brass can leach zinc, leading to “dezincification” and potential contamination. DZR brass is a requirement of a number of international drinking water standards approved and widely used for both domestic and commercial systems.
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Stainless Steel:
316 Grade offers a high-level of corrosion resistance, hygiene, and durability, making it a premium choice for long-term system durability, public health. and projects where corrosive elements may be present. .
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Plastic (PVC/ PP/Nyglass):
Where approved, these options provide a hygienic, lightweight, and corrosion resistant option. Particularly polypropylene/nyglass options can be beneficial in environments which may be subject to freezing. These valves are more suited to cold water applications and not suited to elevated temperatures particularly for ongoing operation. It is important however, to ensure whichever plastic valve option you consider does have the required potable water approvals.
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Other Materials:
Ductile iron and cast iron are commonly specified particularly for larger valving such as Butterfly Valves, Resilient Seated Gate Valves, Y Strainers, and Non-Return Valves, but should have approved internal linings and componentry. Always check manufacturer certification.
4. What certifications and features should you look for in NZ?
Regulators throughout New Zealand are requiring potable water valves to hold the Watermark, or equivalent recognised standards including some international standards such as DVGW. These standards guarantee that the materials and design are safe for direct contact with drinking water.
Also consider:
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Full-bore vs reduced-bore:
Full-bore valves maintain an open bore and reduce pressure loss making them a preferable option in many potable water applications.
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Operation Method
: Are you isolating, regulating, or automating? Lever handles are a simple and easy to use method for isolating valves. Gearbox operation allows for slower operation, eliminating water hammer, and allows for some finer flow control. Actuated systems, electric or pneumatic, enable remote or automated control.
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Connection type
: What’s the best connection method? Do you need to be able to remove the valve for servicing? What size pipework are you working with? These questions will help you in selecting the best connection type. threaded, flanged, or solvent-weld (for PVC).
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Sizing & pressure rating
: Always match system requirements and allow a safety margin (check maximum flow rates, pressure rating and pressure loss).
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Local support:
Choose valves with strong local supply chains like Waterworks for spares or urgent replacements.
5. What’s the best valve for your potable water project? (Scenarios & recommendations)
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Residential:
DZR brass or stainless steel ball valves at entry points, mains, and hot water cylinders. Check valves to protect against backflow where rainwater or irrigation is connected.
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Farms/Lifestyle blocks:
Durable and approved PVC or PP valves and DZR brass ball valves for troughs, tanks, and pumps.
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Municipal & commercial:
Stainless steel, DZR brass, PVC, Ductile Iron ball, butterfly, gate, or non-return valves for distribution mains and plant, with dedicated control valves for dosing or treatment.
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Retrofits:
Look to replace old or corroded valves with certified, modern alternatives, improving both compliance and reliability.
Key Takeaways for NZ Water Systems
The “best valve” depends on your application, local regulations, and the specifics of your installation. Always select valves carrying the required approvals and appropriate materials for your water source and location. Smart choices minimise maintenance, support safe water delivery, and provide long-term system durability.
Need help specifying the right valve?
Get in touch with Waterworks for expert advice, dependable products, and support for all your potable water valve needs.
www.waterworksnz.co.nz