OT:RR:CTF:EMAIN H345780 MFT
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