Using Ball Valves for Drinking Water
Figure 1: Brass ball valve with a drinking water certification
Ball valves are one of the most common types of valves used for drinking water applications for residential and commercial use. It is important to state that the domestic water distribution system is the responsibility of the property owner and not the government. This also applies to drinking water in commercial or industrial buildings. The responsibility of ensuring proper drinking water quality from a public supply stops at the entrance to your building. The standards for piping equipment that will interact with drinking water are quite strict. The materials that come in contact with drinking water can introduce impurities or serve as a breeding platform for organisms that affect the quality of the water.
There are several considerations when selecting a ball valve for drinking water. The valve needs to be corrosion-free, resistant to chemical and electrical reactions, anti-legionella, etc. Also, consumer end components need to be maintenance-free, it must completely shut-off when closed, it should be compact, and easy to use. There are certifications and regulations applicable to valves and other components that come in contact with drinking water.This article discusses ball valves suitable for use with drinking water.
Ball valves for drinking water
Table of Contents
- What is a ball valve?
- Drinking water valve requirements
- Main drinking water valve features
- Conclusion
What is a ball valve?
A ball valve is a quarter-turn valve type. This means a 90 degrees turn will move the valve from the fully closed position to the fully open position. The valve consists of a ball with a hollow center where water passes through, as seen in Figure 2. Ball valves are popular in domestic and industrial applications. They are low cost, available with a wide variety of end connection types and maintain a consistent performance after several years of use. They can operate over a wide range of pressure and temperature, easy to install and replace, and can function for a long period without maintenance.
Figure 2: Components of a ball valve: handle (A), handle screw/bolt (B), shaft seal (C), shaft (D), ball (E), seal (F), and body (G).
Drinking water valve requirements
In domestic water distribution systems, the valves are often permanently installed. Over time, a water valve can degrade causing potential contamination and enabling microbial growth. Therefore, it is important to select a valve type that meets several requirements for drinking water. A good practice is to check the manufacturer’s documentation for compliance of the valve for drinking water applications. For more information on drinking water requirements, you can also read our drinking water article.
Depending on the country, there are different certifications and regulations required for valves that come in contact with drinking water. Some of these are:
Kiwa Water Mark
The Kiwa Water Mark is a Dutch certification for products that come in contact with drinking water. It covers both private and public water system requirements.
NSF (National Sanitation Foundation) – North America
The NSF is a North American product testing, inspection and certification organization. Components such as plumbing, water treatment chemicals and all other equipment that come in contact with drinking water are certified by the NSF Water Division.
WRAS (Water Regulations Advisory Scheme) – Great Britain
The WRAS certification affirms that a component such as water fittings, plumbing systems and equipment supplied with water from the public water supply, complies with the standard set out by the water regulations in the United Kingdom.
DVGW-W270 – Germany
The DVGW-W270 is a guideline and certification for the drinking water sector in Germany. It includes a test, according to the W270 worksheet, that checks bacteriological growth in a drinking water component.
ACS (Attestation De Conformite Sanitaire) – France
ACS is a mandatory approval in France for materials of equipment that come in contact with drinking water for human consumption.
WaterMark – Australia and New Zealand
The WaterMark is a mandatory certification scheme in Australia and New Zealand for plumbing and drainage products that come in contact with drinking water.
Figure 3: Drinking water certifications
Main drinking water valve features
Drinking water ball valves will generally have the following features:
- Material: It is important for the housing and seal material to not corrode, are resistant to wear, and do not affect the properties of the drinking water.
- Anti-legionella: For standard ball valves, there is a dead space around the ball that is created when the line pressure pushes the ball against the rear seat ring. This results in a good seal, but allows fluid to go between the front seal and the ball into the dead space. This can become stagnant water encouraging the growth of bacteria. For an anti-legionella ball valve, an extra hole exists to drain water around the ball.
- Bore size: Full port ball valves have a hole the size of the pipe diameter. This means the valve creates no resistance to the water flow.
- Handle: Typically, a hand lever is on the ball valve that can move 90° to turn ON/OFF. If the handle is perpendicular to the pipe, it is OFF.
- Handle material: The handle material can be made of steel or plastic since it does not come in contact with the drinking water.
To learn more about making the right selection of ball valves for your application, read our ball valve selection article.
Conclusion
Drinking water ball valves are reliable and durable shut-off valves for both domestic and industrial applications. They are simple, cheap, require little to no maintenance, and are easy to install and use. Drinking water valves should meet the local certification requirements. Valves that are not certified may be susceptible to legionella contamination and may be illegal. Always check for the necessary regulations for your application.