By Rick Andrew

In 2001, shower filter manufacturers were seeking to level the playing field in the market place. They were concerned that there was no criteria for ensuring that shower filtration products were safe and that there was no common basis for making claims of product performance and treatment capability. This situation made it difficult for consumers to arrive at educated purchase decisions.

Their search for fair play in the marketing of these systems and increasing consumer confidence in their safety and effectiveness led them to NSF. Specifically, the Joint Committee on Drinking Water Treatment Units (DWTUs) agreed to develop a national consensus standard on shower filters. A task group consisting of shower filter manufacturers, regulatory representatives and product certification specialists was formed to begin fleshing out the requirements for the new standard.

After three years of development and the efforts of many dedicated volunteers, NSF/ANSI 177 Shower filtration systems—Aesthetic effects was officially adopted in September of this year.

Requirements of the standard
NSF/ANSI 177 was developed using the NSF/ANSI DWTU standards as a template. This approach made sense because shower filters and drinking water filters have many common elements, and therefore many common concerns with respect to standards. As a result, the requirements and format of NSF/ANSI 177 are quite similar to the DWTU standards (See Figures 1 and 2).

Specifically, NSF/ANSI 177 has sections specifying requirements for:

  • Material safety. Materials in contact with shower water must not contain lead as an intentional ingredient, except for lead-free brass. Materials in contact with shower water must not be solvent bonded.

A formulation disclosure and review for each material in contact with water is required to verify that the materials do not contain lead. A review of manufacturing processes is required to establish that there is no solvent bonding of shower water contact materials. In a departure from the DWTU standards, no extraction test is required. Because shower water is not considered drinking water, it is sufficient to base material safety conformance on the formulation review and prohibition of solvent bonding.

  • Structural integrity. Two tests of structural integrity are required: 15 minute hydrostatic testing and cyclic testing. The cyclic test is 10,000 cycles for open discharge systems and 100,000 cycles for non-open discharge systems. The test pressures vary depending on whether the system is open discharge or not. This is similar to the DWTU standards.

The significant difference from the DWTU standards is that the structural integrity testing is conducted at elevated temperatures representative of shower temperatures, as opposed to room temperature. The hydrostatic test is conducted at 49° C, representative of the hottest hot water settings; while the cyclic test is conducted at 40° C, which is reflective of typical hot water temperatures.

  • Minimum performance. Among other various requirements, shower filter systems must be designed to operate at a maximum temperature of at least 49° C and maintain a minimum service flow of at least 1.0 gallon per minute (gpm).
  • Free available chlorine reduction. Shower filter systems must reduce an influent challenge of 2.0 mg/L free available chlorine by at least 50 percent throughout their rated service life, consistent with the chlorine reduction requirements of NSF/ANSI 42—Drinking water treatment units—Aesthetic effects. Like the DWTU standards, two units are tested. At least five passing sample points are required to establish the rated service life. Like structural integrity, this test is also conducted at an elevated temperature of 40° C. The influent challenge is cycled on and off at 15 minute intervals, to simulate shower usage. A dynamic influent pressure of 80 psig is used, and flow is controlled to the manufacturer’s rated service flow. If the flow rate drops below 1.0 gpm, the test is terminated.

Test water must have a total chloramines concentration of < 0.1 mg/L, as studies conducted during the standard development process indicated that chloramines can interfere with the ability of certain media used in many shower filter systems to reduce free available chlorine.

Because chlorine is volatile and reactive, samples of the influent and effluent collected for analysis of free available chlorine must be analyzed within one minute of collection. Influent samples must be collected from the pressurized manifold immediately upstream of the test units, and samples of the effluent must be collected at a distance not exceeding one foot from the showerhead.

  • Product literature. The following pieces of product literature are required, with specific information stipulated for each:
  1. Installation, operation, and maintenance instructions
  2. Data plate
  3. Replacement elements
  4. Performance data sheets

Information requirements for each of these pieces of product literature are similar to those of the DWTU standards. The underlying philosophy is that information provided should allow consumers to understand the product, find replacement elements and contact the manufacturer if they need additional information.
There is a specific statement required in the performance data sheet to help convey to consumers the capabilities of the product:

“This system has been tested according to NSF/ANSI 177 for reduction of free available chlorine. The concentration of free available chlorine in water entering the system was reduced to a concentration less than or equal to the permissible limit for water leaving the system, as specified in NSF/ANSI 177. This system has not been evaluated for free available chlorine reduction performance in the presence of chloramines. Free available chlorine reduction performance may be impacted by the presence of chloramines in the water supply. Please contact your local water utility to determine if chloramines are used in treating your water.”

NSF/ANSI 177 helps level the playing field
In the early 1970s, the DWTU market was largely unregulated. Legitimate manufacturers had concerns that consumers were not able to distinguish their quality products from poor quality products that made outlandish claims of performance. With the adoption of NSF/ANSI Standard 42 in 1973, and NSF/ANSI Standard 53—Drinking water treatment unitsHealth effects in 1980, these manufacturers had the tools necessary to demonstrate the quality and performance of their systems.

Now, in 2004, with the adoption of NSF/ANSI 177—Shower filtration systemsAesthetic effects, the shower filter industry has a similar tool available to them to demonstrate quality and the ability of their systems to reduce free available chlorine. With a very specific test method for demonstration of free available chlorine reduction, the replacement element capacities for various systems will be comparable. This will help eliminate consumer confusion and help potential purchasers sort through the marketplace to make wise purchase decisions.

About the author
Rick Andrew has been with NSF International for over five years, working with certification of residential drinking water products. He has been the Technical Manager of the Drinking Water Treatment Units Program for over two years. His previous experience was in the area of analytical and environmental chemistry consulting. Andrew has a bachelor’s degree in chemistry and an MBA from the University of Michigan. He can be reached at 1-800-NSF-MARK or email:


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