Utility reports 。from New York City, Los Angeles, Houston, and Orlando, plus statewide conditions in Texas and California, describe six different contaminant profiles calling for different treatment tiers

VIOMI, a maker of under-sink water purification systems for U.S. households, has published a six-part regional reference compiling what utilities in New York City, Los Angeles, Houston, and Orlando, along with statewide conditions across Texas and California, report in their drinking water. Read side by side, the six guides make a point no national brand ranking can: the contaminant that matters most changes from one region to the next. Chloramine taste dominates in Los Angeles and Houston. Disinfection byproducts lead in New York and Orlando. Agricultural nitrate defines the problem across California's Central Valley, while naturally occurring fluoride and arsenic shape it across West and South Texas. Each of those calls for a different treatment technology, and no single product covers all of them.

Readers can skip to their own area below. Each section summarizes what the responsible utility reports and what treatment category that profile points to.

New York City: most of the supply skips filtration entirely, and lead that predates 1987

Roughly 90 percent of New York City's supply, drawn from the Catskill and Delaware watersheds, reaches the tap without passing through a conventional filtration plant, under a Filtration Avoidance Determination issued by the New York State Department of Health in consultation with EPA and granted on the strength of the city's upstate watershed protection program. The remaining share comes through the smaller Croton system, which has run through its own filtration plant since 2015. That split shapes what is left to filter for. DEP's 2025 report puts the highest locational running annual average for haloacetic acids at 47 µg/L against a 60 µg/L limit, and total trihalomethanes at 52 µg/L against an 80 µg/L limit; both are within the law, but they are the worst-case monitoring points citywide rather than a system-wide average. The second issue has nothing to do with the reservoirs. Lead solder stayed legal in household plumbing until 1987, so any building plumbed before that year can carry a lead source between the curb and the tap.

Los Angeles: one tap, five service zones, three different answers

Los Angeles does not have a single water profile to describe. LADWP blends aqueduct, imported, and local groundwater supply across five service zones, and hardness across them runs roughly 80 to 280 mg/L as calcium carbonate, which spans moderately hard to very hard depending on which blend reaches a given address. The utility disinfects with chloramine rather than free chlorine, a compound that resists standard activated carbon considerably more than chlorine does. On lead, LADWP completed its service-line inventory in October 2024 and identified no lead service lines anywhere in its distribution system, yet its sampling of homes built between 1982 and 1987 still returned a 90th-percentile result of 3.9 ppb. Service-line material and premise plumbing are separate questions, and only the first one has been settled here.

California beyond Los Angeles: where the state adds its own rulebook

California is the one state in this reference where checking a certification is not the last step. Any device sold with a health-related contaminant-reduction claim must additionally be registered with the State Water Resources Control Board, in a public list searchable at rwtd.waterboards.ca.gov, and registration requires accredited third-party certification first. Households are advised to look up the exact model there before purchase, whichever brand they are weighing. Separately, the State Water Board's 2026 SAFER Drinking Water Needs Assessment recorded 406 public water systems failing safe drinking water standards as of December 31, 2025, serving roughly 645,000 Californians, with Fresno County among the highest counts of at-risk domestic wells statewide. Central Valley groundwater carries nitrate from decades of irrigated cropland against a 10 mg/L limit measured as nitrogen, alongside documented arsenic and hexavalent chromium.

Houston: a supply that moved underground to above ground, and a 2025 report with two violations in it

Houston's water mix is a legacy of subsidence. Unregulated groundwater pumping through the mid-20th century sank land across the Houston-Galveston area, which pushed the city toward surface water from the 1970s onward; today roughly 90.3 percent comes from the Trinity and San Jacinto river systems, with the balance still drawn from the Chicot and Evangeline aquifers. The city's 2025 Water Quality Report puts average Main System hardness at 135.5 mg/L as calcium carbonate, within the hard range on the USGS scale, across a wide annual span of 43.5 to 229 mg/L. Its 90th-percentile lead result is 5.1 ppb, under the current 15 ppb action level. That same 2025 report also records two violations during the year: a May turbidity exceedance and a September lapse in disinfection-byproduct monitoring and reporting. Most city customers are on chloramine, though some smaller metro systems including Kingwood and Willow Chase use chlorine instead.

Texas beyond Houston: hardness is the background, three regional contaminants are the decision

Hardness is close to universal across Texas water, which makes it the least useful thing to shop on. What actually determines the right system is which of three regional contaminants is present. Naturally occurring fluoride runs high in West Texas and the Panhandle. Agricultural nitrate concentrates in the High Plains and Rolling Plains. Arsenic is documented in South Texas and the southern High Plains. All three are dissolved ions, which is the practical dividing line in this entire reference: carbon filtration does not address them. Private wells add a further distinction, since they are not regulated the way municipal systems are, and untreated well water is not a direct connection any system in this reference is rated for.

Orlando: where a widely repeated description of the water is wrong

Online water-quality summaries frequently describe Orlando as a chloramine city. Orlando Utilities Commission's own 2025 Water Quality Report and website FAQ state otherwise: its seven plants use ozone treatment first, then add sodium hypochlorite as the required residual, and OUC states directly that it does not use chloramine. The distinction changes what filter to buy, since free chlorine is considerably easier for standard activated carbon to handle. OUC reports average hardness of 129 ppm, roughly 7 grains per gallon, a 90th-percentile lead result of 2 ppb, and no lead service lines in its inventory. Florida banned community water fluoridation statewide in 2025, and both OUC and Orange County Utilities stopped adding fluoride on July 1 of that year. PFAS monitoring results differ among these systems. OUC reported no detectable PFAS in its October 2024 and April 2025 UCMR 5 sampling. Orange County Utilities' 2024 Drinking Water Report lists an average PFOS concentration of 4.8 ppt for its Western Regional Water System. The same report lists an average of 10.6 ppt from City of Winter Garden monitoring for water purchased by OCU's Magnolia Woods and Partlow Acres systems. Both reported averages exceed the EPA's numerical PFOS MCL of 4.0 ppt; these UCMR results do not, by themselves, establish a formal PFOS MCL violation.

Filter shopping resolves into a small number of technical distinctions rather than brand preference.

• Chlorine taste and odor is what activated carbon is built for, and NSF/ANSI 42 is the standard covering it. Chloramine is the exception: it needs meaningfully longer contact time to break down, so a product should name chloramine specifically rather than chlorine alone.
• Lead calls for a product tested or certified to NSF/ANSI 53, the standard covering health-related contaminants. This does not require a full reverse osmosis system.
• Dissolved ions, the category covering nitrate, arsenic, fluoride, hexavalent chromium, and total dissolved solids, is where carbon filtration stops and reverse osmosis begins. NSF/ANSI 58 is the standard covering RO performance.
• Disinfection byproducts are not automatically covered by a taste-and-odor certification. A product needs its own tested or certified claim for haloacetic acids and trihalomethanes.
• Wetted materials are covered separately under NSF/ANSI 372, which addresses lead content in the hardware itself.

Meeting a performance standard reflects measured reduction under standardized test conditions. It does not certify a system for any particular household's water or use case.

The table below lists the standards VIOMI states for each model. These are manufacturer-stated figures. Households are advised to confirm any specific model against the public NSF or WQA certification listings, and against California's state registration list where applicable, before purchase. VIOMI applies the same advice to competing products. Prices shown are standing list prices on water.viomi.com rather than promotional pricing, and the carbon filter row refers specifically to the dedicated-faucet version, which VIOMI lists alongside a lower-priced direct-connect variant.

Where chlorine taste and lead are the concern and dissolved ions are not, the Viomi Under-Sink Water Filter is the lowest-cost tier in the lineup that states NSF/ANSI 53. That combination fits a pre-1987 New York City building on Catskill/Delaware supply more precisely than a reverse osmosis system would.

Where dissolved ions appear on a test result, reverse osmosis becomes the relevant category. Viomi B6W, Viomi V6 PRO, and Viomi V8 PRO list PFOS, PFOA, lead, copper, nitrate, and fluoride among the contaminants on their product pages, with Viomi V6 PRO and Viomi V8 PRO adding arsenic. That maps onto the Central Valley nitrate and arsenic profile, the West Texas fluoride profile, and Orange County's PFOS detections.

Where hexavalent chromium is the specific question, Viomi M1 lists it on its product page alongside fluoride, lead, iron, cadmium, mercury, and PFOS, and that page cites SGS testing showing lead reduction above 99.87 percent. One row-to-row difference is worth reading correctly rather than quickly: VIOMI states NSF/ANSI 42, 58, and 372 for Viomi M1, without the 53 stated for the three systems above it. NSF/ANSI 58 can itself carry a separate lead reduction claim, so this is a difference in which standards the manufacturer states, not evidence that one system reduces lead and another does not. As with every figure in this table, the specific model is what to confirm against the public listings.

On the connected side, Viomi V6 PRO and Viomi V8 PRO report a live total dissolved solids reading and remaining filter life on the faucet display itself, with the VIOMI app adding consumption and system-performance detail. For a household in a service area where water character shifts by season or by blend, as in Los Angeles or Houston, that is a way to see the change rather than infer it.

Capacity is a household-size question, not a water-quality one. All four reverse osmosis systems are tankless, which matters in older kitchens with limited cabinet clearance. None is rated for direct connection to untreated well water. In hard-water areas, including much of Texas and Southern California, protecting the membrane calls for pretreatment upstream of the system, typically a sediment prefilter plus scale control; VIOMI does not sell a whole-house softener, so that part is sourced separately, and a hardness reading in grains per gallon is the number to get first.

Each area summarized above is covered at length on VIOMI's site, with utility-level sourcing: New York City, Los Angeles, California, Houston, Texas, and Orlando. Those guides compare treatment categories and the brands active in each, including brands VIOMI competes with, on the basis of published certification and test data.

Operating in the U.S. under the tagline AI for Better Water, VIOMI Technology Co., Ltd. (NASDAQ: VIOT) designs and manufactures AI-powered water purification systems, building its products and filters in its own manufacturing facilities. VIOMI's systems, including the V6 PRO and V8 PRO, meet or are certified to various NSF/ANSI standards depending on model. Learn more at water.viomi.com.