Application for Further Review of Protest No. 2704-23-168738; Classification of Sand and Cartridge Filter Systems from China

H345780 February 3, 2026 OT:RR:CTF:EMAIN H345780 MFT CATEGORY: Classification TARIFF NO.: 8421.21.00 Center Director, Machinery C.E.E. U.S. Customs and Border Protection 301 E. Ocean Blvd. Long Beach, CA 90802 Re: Application for Further Review of Protest No. 2704-23-168738; Classification of Sand and Cartridge Filter Systems from China Dear Center Director: The following is our decision on the Application for Further Review (AFR) of Protest No. 2704-23-168738, which was filed on December 5, 2023, on behalf of Aquapro Systems, LLC (protestant). The Protest and AFR concern the applicability of U.S. Note 20(ttt)(i)(23) to Chapter 99 of the Harmonized Tariff Schedule of the United States (HTSUS) regarding certain sand and cartridge filter systems from China. In reaching the determination below, U.S. Customs and Border Protection (CBP) has considered information submitted with the Protest and AFR, including supplemental information provided on May 16, 2025, pursuant to an oral discussion of the issues held on April 22, 2025. FACTS: At issue are sand filter systems (hereinafter “sand filters”) and cartridge filter systems (hereinafter “cartridge filters”), which are devices used to filter out dirt and debris from swimming pool water. The sand filters are mainly comprised of a multiport valve; tank; filter assembly; drain plug; hose adapter and clamp; pump; pressure gauge; and strainer basket. When in use, incoming water from the piping system is fed from the piping system into the sand filters’ multiport valve to the top of the filter bed. As the water is pumped through the filter media (i.e., sand), the filter bed traps dirt and debris. The water then flows to the bottom of the filter tank, through the multiport valve, and back through the piping system to return to the pool. The cartridge filters are primarily comprised of a pressure gauge; manual air relief assembly; upper and lower filter body; air relief filter; cartridge element; adapter; outlet pipe; and inlet elbows. During operation, dirt and debris collect on the cartridge element as water flows into the cartridge filter. The accumulated dirt and debris cause a resistance to the flow of pool water within the filter housing, which raises the internal pressure as indicated by the pressure gauge located at the top of the cartridge filter. A pressure reading between 8 and 10 psi higher than an initial measurement – or a noticeable decrease in water flow – would indicate that the cartridge element needs to be cleaned or replaced to remove the accumulated dirt and debris from the filter. The cartridge filters similarly release filtered water back into the pool. The subject merchandise was entered between May 2, 2022, and October 8, 2022. CBP liquidated each of the subject entries on July 28, 2023, and August 11, 2023, under statistical reporting number 8421.21.0000 of the HTSUS Annotated (HTSUSA), which provides for, “Centrifuges, including centrifugal dryers; filtering or purifying machinery and apparatus, for liquids or gases; parts thereof: Filtering or purifying machinery and apparatus for liquids: For filtering or purifying water.” There is no dispute that the subject merchandise is classifiable under statistical reporting number 8421.21.0000, HTSUSA. Rather, the protestant claims that U.S. Note 20(ttt)(i)(23) to Chapter 99, HTSUS, excludes the subject sand filters and cartridge filters from the additional duties imposed by Section 301 of the Trade Act of 1974 under heading 9903.88.01, HTSUS. ISSUE: Whether the subject sand filters and cartridge filters each constitute “[f]iltering or purifying machinery or apparatus of a kind used for waste water treatment (described in statistical reporting number 8421.21.0000)” under U.S. Note 20(ttt)(i)(23) to Chapter 99, HTSUS. LAW AND ANALYSIS: A decision on classification and the rate and amount of duties chargeable is a protestable matter under 19 U.S.C. § 1514(a)(2). The subject protest was timely filed on December 5, 2023, within 180 days of liquidation, pursuant to 19 U.S.C § 1514(c)(3). Further review of Protest No. 2704-23-168738 is properly accorded to the protestant pursuant to 19 C.F.R. § 174.24(b) because the decision against which the protest was filed is alleged to involve questions of law or fact which have not been ruled upon by the Commissioner of CBP or his designee or by the Customs courts. Specifically, CBP has not previously ruled upon the language of the exclusion note at issue, nor its applicability to pool water filtration machinery. Classification under the HTSUS is in accordance with the General Rules of Interpretation (GRIs). GRI 1 provides that the classification of goods will be determined according to the terms of the headings of the tariff schedule and any relative section or chapter notes. In the event that the goods cannot be classified solely on the basis of GRI 1, and if the headings and legal notes do not otherwise require, the remaining GRIs 2 through 6 will then be applied in order. 2 The HTSUSA provision under consideration is as follows: 8421 Centrifuges, including centrifugal dryers; filtering or purifying machinery and apparatus, for liquids or gases; parts thereof: Filtering or purifying machinery and apparatus for liquids: 8421.21.0000 For filtering or purifying water U.S. Note 20(ttt)(i) to Chapter 99, HTSUS, provides as follows, in pertinent part: The U.S. Trade Representative determined to establish a process by which particular products classified in heading 9903.88.01 and provided for in U.S. notes 20(a) and 20(b) to this subchapter could be excluded from the additional duties imposed by heading 9903.88.01. See 83 Fed. Reg. 40823 (August 16, 2018) and 83 Fed. Reg. 47326 (September 18, 2018). Pursuant to the product exclusion process, the U.S. Trade Representative has determined that, as provided in heading 9903.88.67, the additional duties provided for in heading 9903.88.01 shall not apply to the following particular products, which are provided for in the enumerated statistical reporting numbers: [. . .] (23) Filtering or purifying machinery or apparatus of a kind used for waste water treatment (described in statistical reporting number 8421.21.0000) The rules of interpretation that govern the classification of merchandise throughout the Nomenclature apply, perforce, to legal notes in Chapter 99, HTSUS.1 GRI 1 requires that the subject merchandise meet the terms of the relative chapter notes – in this instance, Note 20(ttt)(i)(23) to Chapter 99, HTSUS. To be excluded from the additional Section 301 duties imposed by subheading 9903.88.01, HTSUS, the subject sand filters and cartridge filters must constitute “[f]iltering or purifying machinery or apparatus of a kind used for waste water treatment” and meet the description found in statistical reporting number 8421.21.0000, HTSUSA [emphasis added]. While the merchandise plainly constitutes filtering machinery for filtering water under statistical reporting number 8421.21.0000, HTSUSA, the crux of this matter turns on whether the filters are “of a kind used for waste water treatment.”2 Neither the HTSUS nor the ENs provide a definition for “waste water treatment.” In the absence of a definition of a term in the HTSUS or ENs, the term’s correct meaning is its 1 See, e.g., Keystone Auto. Operations, Inc. v. United States, 781 F. Supp. 3d 1362, 1371–73 (Ct. Int’l Trade 2025) (rejecting the plaintiff’s contention that certain information presented in a Federal Register notice “supplant[ed] longstanding judicial precedent on interpreting HTSUS provisions”). 2 We note that the term “waste water,” as used in the exclusion note, is commonly rendered as “wastewater.” See waste, adj. meanings, etymology and more, OXFORD ENG. DICTIONARY, https://doi.org/10.1093/OED/6455518222 (last visited Jan. 26, 2026) (“9.c. waste water (now frequently written as one word)”). This decision and several sources cited throughout will use the one- and two-word variants interchangeably. 3 common and commercial meaning.3 The common and commercial meaning may be determined by consulting dictionaries, lexicons, scientific authorities, and other reliable sources.4 Academic sources on wastewater treatment consistently locate the topic within the civil and environmental engineering disciplines and contemplate treatment plant processing and design. For example, the opening chapter on Wastewater Engineering: Treatment and Recovery, an “authoritative book on wastewater treatment,”5 underscores how the term “wastewater treatment” narrowly relates to municipal and industrial plants and the processes exhibited therein.6 The chapter features: (1) a schematic diagram of wastewater collection system infrastructure;7 (2) a discussion of federal regulations that affect facility design;8 (3) a table on the minimum national standards for “secondary” wastewater treatment;9 (4) a table listing the seven levels of wastewater treatment – ranging from a “preliminary” level that is designed to remove constituents which may disrupt downstream “operations, processes, and ancillary systems” to an “advanced” level that is implemented “after normal biological treatment”;10 and 3 See Nippon Kogaku, Inc. v. United States, 69 C.C.P.A. 89, 92 (Ct. Cust. App. 1982) (stating that to determine the intent of the legislature, “tariff terms are to be construed in accordance with their common and commercial meanings, which are presumed to be the same”). 4 See C.J. Tower & Sons v. United States, 69 C.C.P.A. 128, 134 (Ct. Cust. App. 1982) (citing Schott Optical Glass v. United States, 67 C.C.P.A. 32, 34 (Ct. Cust. App. 1979)). 5 See Wastewater Engineering: Treatment and Resource Recovery, MCGRAW-HILL, https://www.mheducation.com/highered/product/wastewater-engineering-treatment-and-resource-recovery-metcalf- and-eddy.html?viewOption=student (last visited Feb. 3, 2026) (overview). 6 See GEORGE TCHOBANOGLOUS ET AL., WASTEWATER ENGINEERING: TREATMENT AND RESOURCE RECOVERY 3 (5th ed., 2014) (defining “wastewater” as “essentially the water supply of the community after it has been used in a variety of applications and which now contains constituents that render it unsuitable for most uses without treatment”) (emphasis added). 7 See id. at 4 (illustrating the collection of wastewater from “[r]esidential houses, apartments, office buildings, commercial establishments, etc.” for treatment at a facility). 8 See id. at 8–9. 9 See id. at 7–8. The authors describe “secondary” wastewater treatment as including “three major effluent parameters: biodegradable organics, expressed in terms of five-day biochemical oxygen demand (5-d BOD); total suspended solids (TSS); and the hydrogen ion concentration expressed as pH.” Id. at 7. The standards found in this table “provided the basis for the design and operation of most wastewater treatment plants.” Id. 10 See id. at 13. 4 (5) a figure outlining the four “typical flow diagrams for the treatment of wastewater and biosolids,” including conventional biological treatment, biological nutrient removal, advanced treatment, and anaerobic treatment.11 Discussions or graphical representations of pool water filtration are notably absent. Other textbooks echo this focus on larger treatment processes in discussions of “wastewater treatment” by emphasizing the linear disposal and collection of wastewater as opposed to the circular use of water in a swimming pool filtration context. Fundamentals of Wastewater Treatment and Engineering includes this emphasis in its description of wastewater sources: The following are common sources or types of wastewater: • Domestic or municipal wastewater: this includes wastewater discharged from residences, institutions such as schools and hospitals, and commercial facilities such as restaurants, shopping malls, etc. [emphasis added]. • Industrial wastewater: wastewater discharged from industrial processes, e.g., pharmaceutical industry, poultry processing [emphasis added]. • Infiltration and inflow: this includes water that eventually enters the sewer from foundation drains, leaking pipes, submerged manholes, and groundwater infiltration, among others [emphasis added]. • Stormwater: rainfall runoff and snow melt. Municipal wastewater is usually collected in sanitary sewers and transported to the wastewater treatment plant. Stormwater may be collected in separate sewer lines called storm sewers. In some cities, especially older cities, stormwater is collected in the same sewer line as the domestic wastewater. This type of system is called a combined sewer system. Each system has advantages and disadvantages. Industrial wastewater may be treated on-site, or pretreated and then discharged to sanitary sewers, after appropriate removal of pollutants.12 These descriptions repeatedly touch on the treatment of water that has been removed and collected from certain sources, in contrast to water that has been recycled within a swimming pool. Another textbook, Water and Wastewater Engineering: Design Principles and Practice, includes a chapter titled “General Wastewater Collection and Treatment Design Considerations” and is also silent on swimming pool filtration. Still, there is ample discussion in this chapter on the design of wastewater treatment facilities, including a section on “domestic wastewater flows” 11 See id. at 16. 12 RUMANA RIFFAT & TAQSIM HUSNAIN, FUNDAMENTALS OF WASTEWATER TREATMENT AND ENGINEERING 80 (2d. ed., 2022); see also MACKENZIE L. DAVIS, WATER AND WASTEWATER ENGINEERING: DESIGN PRINCIPLES AND PRACTICE at 18-1-2 (2d. ed., 2020) (providing a similar list of wastewater sources and discharge methods). 5 centered on designing facilities for communities with or without wastewater collection systems.13 More examples abound in the texts, but the weight of authority is sufficient to conclude that the common and commercial meaning of the term “waste water treatment” relates to the processing that occurs in wastewater treatment plants. This interpretation adheres to the “commercial realities and the real-world context of the industries” in which merchandise subject to the exclusion exist.14 To that end, there is no indication that the subject sand filters or cartridge filters act as machinery used in wastewater treatment as contemplated by the exclusion note. The facts instead demonstrate that the merchandise is used in a different environment altogether: in swimming pools. The protestant argues that the subject sand filters and cartridge filters are “analogous” to industrial and municipal wastewater treatment systems because the subject merchandise regularly processes wastewater containing contaminants that are “functionally and compositionally parallel” to the larger-scale systems. The protestant claims that “fibers from articles used in and around the water” are analogous to “textile, food processing, and municipal wastewater treatment systems”; “body oils, lotions, and cosmetics” found in pool water are analogous to “fats, oils, and greases” common in wastewater treatment systems for the restaurant, cosmetics, and chemical manufacturing industries; and so forth. Thus, the protestant asserts, “while concentrations and flow volumes may differ, the core filtration principles and contaminant/pollutant categories are analogous.” Additionally, the protestant claims that the removal of these contaminants prior to reintroduction to a pool is similar to the goal of removing contaminants before effluent is discharged from wastewater treatment systems. The protestant states that the filtration technologies used in industrial and municipal wastewater treatment systems are “identical” to those that the subject merchandise employs. The cartridge filters, the protestant avers, that are used to filter fine particulates from pools are “conceptually akin” to multimedia or membrane fibers used in semiconductor or pharmaceutical pre-treatment. Likewise, sand filters “are employed across the spectrum from residential spas/pools wastewater filter systems to high- volume industrial and municipal wastewater treatment systems.” We disagree and, for the sake of argument, dispute the inherent assumption that a difference in degree cannot become a difference in kind. None of the authorities consulted for the analysis of the common and commercial meaning of “waste water treatment” demonstrate that swimming pool filtration is, in essence, scaled-down versions of wastewater treatment exhibited in plants. Nor do the sources express that swimming pool filtration is commercially fungible with the types of wastewater treatment previously outlined. Instead, the substantially different contexts fairly indicate that swimming pool filtration falls outside of the scope of U.S. Note 20(ttt)(i)(23). 13 DAVIS, supra note 12. Moreover, readers interested in understanding the physical characteristics of domestic wastewater will find descriptions of an “odor of kerosene or freshly turned earth” or “[t]he characteristic rotten-egg odor of hydrogen sulfide and the mercaptans” of fresh sewage, quite unlike the chlorine of swimming pool water. Id. 14 See Idlico Inc. v. United States, 2024 Ct. Intl. Trade LEXIS 122 at *8 (2024). 6 Accordingly, we hold that the subject sand filters and cartridge filters are classified under subheading 8421.21.00, HTSUS, and are subject to the additional Section 301 duties of heading 9903.88.01, HTSUS. HOLDING: By application of GRIs 1 and 6, the subject sand filter systems and cartridge filter systems are classified under heading 8421, HTSUS, specifically subheading 8421.21.00, HTSUS, which provides for, “Centrifuges, including centrifugal dryers; filtering or purifying machinery and apparatus, for liquids or gases; parts thereof: Filtering or purifying machinery and apparatus for liquids: For filtering or purifying water.” The general column one rate of duty is free. Pursuant to U.S. Note 20 to Subchapter III, Chapter 99, HTSUS, products of China classified under subheading 8421.21.00, HTSUS, unless specifically excluded, are subject to an additional 25 percent ad valorem rate of duty and also properly classified under heading 9903.88.01. This ruling does not address the applicability of any additional duties that may apply to the goods discussed herein. Likewise, duty rates are provided for your convenience and are subject to change. The text of the most recent HTSUS and the accompanying duty rates are provided at www.usitc.gov. You are instructed to DENY the Protest. Sixty days from the date of the decision, the Office of Trade, Regulations and Rulings, will make the decision available to CBP personnel, and to the public on the CBP website at www.cbp.gov, by means of the Freedom of Information Act, and other methods of public distribution. Sincerely, for Yuliya A. Gulis, Director Commercial and Trade Facilitation Division 7