Examining residential water treatment control valve and component designs

April 1, 2015

Identifying different valve designs and internal components.

Residential water treatment professionals in today’s market are familiar with the history of water softeners, water filtration and the role they play in residential water treatment. One of the most crucial components of every residential water treatment system is the control valve or filter valve. Without them, the system would never be able to regenerate or backwash. Regenerating is a must in order to recharge the resin bed, and backwashing is necessary to lift the media bed and flush out the trapped contaminants.

With control valves being such a critical component of a water treatment system, it is no wonder there are a wide variety of companies that offer automatic control valves. Today’s dealers and installers have a number of designs and manufacturers to choose from. However, boiled down, there are two main design types. This article will take a look into these two popular designs and the internal components.

Different valve designs

The mechanical softener or filter valve is commonly referred to as a piston-style valve by industry professionals. It has been well over 30 years since this style of water softener control valves hit the market; this same valve design, or a version of it, is still widely used by many manufacturers and distributors in water treatment today. Depending on the manufacturer, the piston is positioned either vertically or horizontally in the valve body to control the water flow during the different cycles of the regeneration/backwash process.

The disc-style design valve has sometimes been referred to as a rotary or multiport valve. This valve moves away from the seal, spacer and piston design, and instead utilizes internal discs that rotate and open the different ports to control the water flow during the cycles of the regeneration process. Now some may have heard that this design is "nothing but trouble," but it depends on the internal components.

Look at the components

Valve design can make a difference in the overall performance of a water treatment system. Certain valve designs deliver higher flow rates, backwash rates and water efficiency, but what really makes this possible are the internal components. These components ultimately control the water treatment system and determine the overall service life of the valve. This should prompt every water treatment professional to carefully consider the composition of the internal components of their preferred valve.

Piston-design valves

The piston-design valves that we find in the marketplace today contain a piston, seals, spacers, O-rings and a brine valve. The design or layout of these components may vary by manufacturer, but these main components are typically present. The piston and brine valve in these systems are commonly made of brass or steel and coated with different brands of PTFE (polytetrafluoroethylene). The brass or steel composition creates a solid base for these parts but PTFE will wear off over time. Once the PTFE wears away and the raw metal is exposed, it will allow the metal to oxidize, and therefore the tolerances of the piston will change. The seals and O-rings are composed of EPDM (ethylene propylene diene terpolymer) or other synthetic rubbers of different compositions.

Rubber is typically a durable material when in constant contact with water. However, chlorine and chloramine found in municipal water supplies will deteriorate rubber over time, making the seals and O-rings susceptible to failure. The spacers that are found in unison with seals are made of plastic. The type of plastic or blend of plastic changes from manufacturer to manufacturer, but one thing is constant — plastic will wear out over time and will need to be replaced.

Disc-design valves

Unlike piston-design valves, the internal components of the disc-design valves vary considerably from manufacturer to manufacturer. However, there is one constant — the internal disc(s) that control the flow of water. Some manufacturers of disc-design valves compose their internal discs of different blends of plastic. Over time plastic of any composition will break down or fail. Other manufacturers use ceramic for their internal disc(s). Unlike plastic, ceramic is a durable material that is more resistant to abrasion, corrosion and wear than stainless steel. Essentially, there is zero wear and degradation over the entire service life of the valve.

There are a couple different versions of the disc-style valve currently available on the market. One design has a stationary ceramic seat with a rotating disc composed of plastic. Over time the plastic disc turning on a ceramic seat is going to wear and will need to be replaced. The other design features a rotating ceramic disc that is paired with a composite stationary disc. This composite shares many of the same beneficial traits of ceramics, offering strength and durability while remaining resistant to corrosion and wear.


Any service or installation professional will tell you that pistons, seals, spacers and O-rings in a piston-design valve wear out and need to be replaced. The same can be said for the internal plastic discs, springs and metal pins used in some brands of disc-design valves while other disc-design valves do not have wearable internal parts that need to be replaced.

It is important that water treatment professionals take the time to consider what makes up the internal components of the valves they are using. Products that are made with the highest quality design and components create higher quality end products. Installing a valve with superior internal components will separate you from your competition in the market. It will also result in less service calls, happier customers and a product you and your company can stand behind.

Jeremiah Jesse and Marcy Stenerson are regional sales managers for the Hankscraft H2O Products division. Jesse has been with Hankscraft for two years and can be reached at [email protected] or 608-524-4341 x 140. Stenerson has been with Hankscraft for eight years and can be reached at [email protected] or 608-524-4341 x 136. Since the 1920s, Hankscraft Inc. has established itself as an industry leader in manufacturing and distribution. Hankscraft H2O Products, a division of Hankscraft, has served the water treatment industry since 2010. Featuring a line of both piston and ceramic disc control valves, Hankscraft H2O also offers complete softening systems, specialty systems to remove iron and sulfur, POU drinking water treatment systems and more.

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