Valves, Pipes, & Hoses for Drinking Water
For drinking applications, it is essential that water does not get contaminated from the water source to the water outlet for drinking. Depending on the application, the water can come into contact with pipes, hoses, fittings and/or valves. These products need to be specially designed, produced, certified, and implemented to ensure they do not cause any health hazards for the consumer. Therefore, it is important to install the correct product, look at the material of your component and to verify it meets the drinking water certifications and regulations in your region.
Hoses, pipes, and valves are checked to ensure the safety of the materials when they come into contact with water. These materials are tested to be neutral in taste, smell, colour and resistant to ozone and water treatment chemicals. In addition, they are created to not make a breeding ground for bacteria and to minimize the formation of biofilm, and therefore, do not contaminate the water. The lead content of these materials is also tested due to the associated health risks.
Tameson offers a wide range of products suitable for drinking water distribution systems for a wide range of operating pressures which come in various functioning capabilities, flow coefficients and operation mechanisms. Common valves implemented for drinking water applications include water shut off valves, check valves for water, water solenoid valves, and float valves for water tanks. Pipes and hoses are meant to transfer the water from point A to point B. It is important to use a water pressure gauge for certain applications to ensure the pressure is within specification.
Choice of material in water pipes, hoses, and valves is a major element in selecting the right product for your application. Here are some tips on selecting among available options.
Standard brass can satisfy European drinking water requirements. However, since brass alloy often has some lead content, strict lead-free requirements in North American drinking water regulations require the OEMs to engage in complicated calculations of wetted surface area and total lead content of a potable water system. However, lead-free brass has been used for products, like water solenoid valves, which can replace traditional brass for these applications.
Valves, hoses, and pipes constructed of composite or plastic material are completely lead-free. Composite materials are the most common material of choice for commercial and residential applications. However, a product constructed of a composite material is commonly slightly more expensive than a metal housing, like brass. As always, it is important to make sure that the flow characteristics, pressure and temperature ratings of the product is appropriate for the application under consideration.
Stainless steel is also completely lead-free and has the broadest range of choice in terms of flow coefficient, sizing, temperature and pressure ratings. Stainless steel products are usually the more expensive choice of material, but are more worry free.
Valve seal materials
NBR is the most commonly used diaphragm, O-rings and seal material for drinking water valves. NBR, also called Nitrile Buna Rubber or Buna-N, is the perfect seal material for neutral fluids. It can withstand temperatures from -18° C up to +90° C continuously. This rubber is a basic choice for seal material in water solenoid valves.
Another choice of seal material for a higher temperature range in water applications is Ethylene Propylene Diene Monomer (EPDM). EPDM has a slightly higher resistance to heat (up to 120° C) and is the perfect seal material for cold and hot water applications.
Certification and Regulation
Here is a list of most commonly known certifications and regulations applicable to water valves, pipes, and hoses.
Kiwa Water Mark
The Kiwa water mark is for products that come into contact with drinking water for the Dutch market. This single mark allows for producers and suppliers to only deal with one set of requirements.
NSF (National Sanitation Foundation) – North America
In North America, water treatment or distribution products such as valves, gaskets, pipes and hoses are recommended and, in most states, required to comply with NSF/ANSI 61.
WRAS (Water Regulations Advisory Scheme) – Great Britain
All water fittings in contact with the public mains water supply must comply with Water Supply Regulations in UK or Scottish Byelaws. WRAS provides quality testing for products and materials to demonstrate full compliance with these regulations and byelaws. The scheme consists of material safety and mechanical testing.
KTW/W270 – Germany
KTW is a guideline on the hygienic assessment of organic materials such as plastics and silicones in contact with drinking water, and W270 describes a method for the assessment of microbial growth on non-metallic materials in contact with drinking water. The DVGW (Deutscher Verein des Gas- und Wasserfaches) provides the required testing and certification for these products.
ACS (Attestation De Conformite Sanitaire) – France
The ACS is a material safety approval mandatory for all materials and products in contact with drinking water in France.
WaterMark – Australia and New Zealand
WaterMark certification scheme is a mandatory certification for plumbing and drainage products for sale in Australia and New Zealand.
Valves for drinking water applications
Water shut off valves
A water shut off valve does, exactly as its name implies, shut off the water. In a house, there are numerous water shut off valves located along the water lines. There is a ‘main’ water shut off valve, that will shut the water off to the entire house. However, along the water pipe, where they branch off and often before appliances (toilets, sinks, etc.) there are additional water shut off valves. This allows you to shut off water to a particular section rather than the entire house. The most common type of water shut off valve is a ball valve. Gate valves, globe valves, and angle seat valves are also commonly used as water shut off valves for water lines going to appliances.
Check valves for water
Check valves for water are also called ‘backflow preventers’ as they prevent the backflow of water. They only require water flow in the intended direction and prevent any flow in the opposite direction. Typically, these are required by plumbing codes to prevent the backflow of contaminated water into the potable water source. Check valves are also used on private well systems to keep the water in the pressure tank and to keep the pump primed. Spring loaded check valves are the most commonly used as they are cheap, close quickly but still prevent water hammer, and have good sealing properties.
Water solenoid valves
In a house, water solenoid valves are generally incorporated into machines that require an intermittent water supply, like a dishwasher or washing machine. When the machine requires water from the main line, it will power the solenoid valve to receive water and cut the power when it deems necessary. Water solenoid valves are a good option for this as they are quick, reliable, and have good sealing properties. Depending on the application, a specific drinking water certification may not be required.
Water solenoid valve considerations
Solenoid valves are very fast acting, therefore, often times a water hammer could occur. Therefore, for certain applications it is important to get a valve with an adjustable closing time, like these slow closing water solenoid valves. Port size and thread types are also important while specifying your valve. For example, a 1/4 inch BSPP water solenoid valve will not work properly if the input port has 1/4 inch NSP threads. Knowing what voltage you have available at the installation location is important. Common voltages are:
Float valve for water tanks
A float valve for water tanks controls the inflow of water into the tank by how high the water level is. They often used for toilets as well as different types of water supply tanks to prevent them from overflowing. As the water level rises, the float mechanism rises with it to a pre-set point that it then triggers the valve to stop water from coming in. As water leaves the tank, the float goes down and re-opens the valve. So, when a toilet is flushed the float mechanism drops down allowing water to enter the tank and when the tank is full the float mechanism is at the top and then shuts off the valve to prevent overflow and to have readily available water. These types of valves are also called flapper valves, siphon valves, and ballcock valves.
Water pipes and hoses
Water pipes and hoses are used to transport water from point A to point B. For main water lines, pipes are used as they are more durable. However, for a water supply that needs to be flexible, like a garden hose, connection to a machine, or in a warehouse, often times a hose is used and having it flexible allows for it to be moved more easily. To ensure the water quality doesn’t get contaminated, these hoses and pipes are subject to various regulations. In Europe, the main governing regulation is the Drinking Water Directive (98/83/EC) and in the USA the main regulation is the Safe Drinking Water Act (SDWA).
The three main points in terms of drinking water quality are:
- Health hazards
- Changes in the smell, taste or color of the water
- Changes to the composition of the water
To meet quality standards and to prevent contamination, hoses cannot leach any chemicals into the water and they must be microbially safe. In addition, hoses suitable for drinking water must be sterilized. Only materials that do not have any detrimental effect on the quality of the drinking water are allowed to be used, therefore the hoses are usually made from FDA/EC approved PVC/PTFE/PU/NBR/EPDM or PE. The pressure of the application should also be taken into consideration to know if you need a special high pressure water hose for water transportation.
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