Miami Water Quality Report 2026: What’s in Your Tap Water

QUICK SUMMARY:

Overall Rating: Fair
Top Contaminants of Concern: Disinfection byproducts (trihalomethanes and haloacetic acids) from chlorinated aquifer water, very hard water from the limestone aquifer, and low-level PFAS and radium
Recommended Filter Type: An NSF 53 carbon block or reverse osmosis system at the tap — see the best under sink water filters and best reverse osmosis systems guides
Water Hardness: Very hard — roughly 22 GPG (about 383 mg/L as calcium carbonate)

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The Miami-Dade Water and Sewer Department (WASD) is one of the largest utilities in the Southeast, serving more than 2.3 million people, and in its most recent Water Quality Report it met every federal health-based standard the EPA enforces. That statement is accurate. It is also where the analysis begins, not where it ends. Miami’s water comes from a shallow limestone aquifer unlike the river supplies of most large cities, and that geology shapes a contaminant profile — hard water, disinfection byproducts, and trace contaminants — that a single compliance headline cannot capture. The distinction matters.

Where Does Miami Get Its Water?

Miami is a groundwater city. WASD draws nearly all of its supply from the Biscayne Aquifer, a shallow, porous limestone formation that sits close to the surface across South Florida. Wellfields pull water from the aquifer, and the department treats it with lime softening and disinfection before distributing it county-wide.

That source explains much of what follows. Because the aquifer is limestone, the water is naturally saturated with dissolved calcium and magnesium — the minerals that make water “hard.” And because the aquifer is shallow and rich in organic material, the water carries a natural organic load that becomes relevant the moment it meets a disinfectant. Two of Miami’s three defining water traits trace directly back to the rock it comes out of.

How Miami Disinfects: Chloramine and Disinfection Byproducts

WASD disinfects with chloramine — chlorine combined with ammonia. The ammonia extends the chlorine residual so it lasts as water travels across one of the largest distribution systems in the country. Chloramine is a deliberate choice for big systems because it produces fewer regulated disinfection byproducts than free chlorine alone.

It does not eliminate them. When any chlorine-based disinfectant reacts with the natural organic matter in aquifer water, it forms two regulated families of compounds: total trihalomethanes (TTHMs) and haloacetic acids (HAA5). In Miami’s warm climate, where higher water temperatures accelerate byproduct formation, these compounds are the contaminants that sit closest to their legal limits. Chloramine is also the most common culprit when residents report a chlorinous taste or odor at the tap. If you want the mechanism behind the disinfectant chemistry, see our explainer on chloramine vs. chlorine in tap water.

What Contaminants Are in Miami Tap Water?

Here is what the data actually shows. The detected levels below come from Miami-Dade’s most recent Water Quality Report and the EWG Tap Water Database; the EWG guideline column reflects health-based targets, which are stricter than the EPA’s enforceable legal limits.

Contaminant	Detected Level	EPA MCL / Action Level	EWG Guideline	Health Concern
Total trihalomethanes (TTHMs)	up to ~63 ppb	80 ppb	0.15 ppb	Bladder cancer, fetal development
Haloacetic acids (HAA5)	up to ~54 ppb	60 ppb	0.1 ppb	Cancer risk
Lead	90th percentile ~3.6 ppb	15 ppb (action level)	0 ppb	Neurological and developmental harm
Radium (combined)	~1.4 pCi/L	5 pCi/L	—	Cancer risk
PFOA / PFOS	~11 ppt / ~36 ppt (earlier monitoring)	4 ppt each (2024 rule)	—	Immune and developmental effects

Three findings deserve attention.

Disinfection byproducts. Haloacetic acids have been measured as high as about 54 ppb — roughly 90 percent of the way to the 60 ppb federal limit — and TTHMs as high as about 63 ppb against an 80 ppb limit. Of Miami’s regulated contaminants, the disinfection byproducts sit closest to their legal ceilings, and they are the most consistently elevated. Both are far above the EWG health-based guidelines, which sit below 1 ppb. These compounds define Miami’s profile the way they define most warm-climate surface- and shallow-groundwater systems.

Hard water. This is the defining physical trait of Miami tap water and the one residents notice first — the scale on fixtures, the spots on glassware, the soap that won’t lather. It is covered in its own section below, but it belongs on any honest list of what is in the water.

Trace contaminants. Lead at the system level is low — a 90th-percentile reading near 3.6 ppb, well under the 15 ppb action level — but as in every city, the service line and premise plumbing are the real variable, not the network average. Radium, a naturally occurring radionuclide common in limestone aquifers, has been detected around 1.4 pCi/L against a 5 pCi/L limit. And earlier PFAS monitoring reported PFOS and PFOA above the EPA’s 2024 federal limit of 4 ppt; monitoring under the new rule is ongoing, and these compounds are now a measured part of Miami’s profile rather than a hypothetical one.

For local context across the full contaminant list, the EWG Tap Water Database entry for Miami-Dade is the most accessible reference.

Miami Water Hardness

Miami’s water is very hard — roughly 383 mg/L as calcium carbonate, or about 22 grains per gallon. On the standard scale (0–3 GPG soft, 3–7 moderately hard, 7–10 hard, 10+ very hard), that places Miami firmly in the very-hard category, near the top of the range for a major US city. The cause is the limestone Biscayne Aquifer, which saturates the water with calcium and magnesium even after WASD’s lime-softening treatment.

In practical terms, this is the trait most Miami households actually feel day to day: scale buildup inside water heaters and on fixtures, cloudy spots on dishes, reduced soap and detergent performance, and shorter appliance life. Unlike the moderate hardness of many northern cities, Miami’s level is high enough that a whole-house water softener is a reasonable consideration for households tired of fighting scale. Our hard water guide walks through when a softener is and isn’t worth the cost.

Best Water Filters for Miami Residents

Miami’s profile points to two needs that pull in slightly different directions: point-of-use filtration for the disinfection byproducts and trace contaminants you drink, and whole-house softening for the hardness you feel. For most households, the drinking-water filter is the higher health priority; the softener is a comfort-and-maintenance decision. The recommendations below focus on the tap, where the contaminants that matter most are best addressed.

Under Sink: Aquasana Claryum 3-Stage

The Aquasana Claryum 3-Stage is WQA-certified to NSF/ANSI Standards 42, 53, and 401 — which means lead and disinfection byproducts (both regulated under Standard 53) are covered by third-party certification, not just a manufacturer claim. For a city where DBPs are the headline regulated risk, that combination is the core requirement. Independent reviewers including Wirecutter have rated Aquasana’s Claryum line well for contaminant reduction relative to its price.

The trade-offs are real. First, the three-cartridge design needs replacement roughly every six months, and the proprietary cartridges cost more than generic carbon blocks — and in Miami’s very hard water, scale can shorten effective cartridge life, so budget for that recurring expense. Second, flow rate drops noticeably as the cartridges load up near end of life, which is the most common complaint in long-term user reviews. It does not soften water, so it will not stop scale on its own.

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Reverse Osmosis: Waterdrop G3P800

For the broadest reduction — disinfection byproducts, PFAS, radium, lead, and most dissolved contaminants in one system — reverse osmosis is the most complete option, and it is especially well suited to Miami because the RO membrane also rejects the dissolved minerals that make the water hard at the drinking tap. The Waterdrop G3P800 holds NSF 58 certification for TDS reduction and NSF 372 certification for lead-free construction. Independent testing by IAPMO confirmed PFOA and PFOS reduction performance, but the membrane itself is not separately NSF 53 certified for PFAS. The tankless design runs at an 800 gallon-per-day rate that avoids the slow refill of older tank-based RO units. See the best reverse osmosis systems guide for the full comparison.

The weaknesses worth weighing: RO wastes water in the filtration process (the G3P800 improves on older units but still sends some water to drain, and that ratio worsens in very hard water), and it strips beneficial minerals along with contaminants, leaving water some people find flat-tasting. It also requires an electrical outlet under the sink and more installation effort than a simple carbon filter.

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Budget Pitcher: ZeroWater 10-Cup Ready-Pour

For renters and anyone not ready to install hardware, the ZeroWater pitcher is IAPMO-certified to NSF/ANSI 53 for lead and chromium reduction, and its five-stage media also drives down total dissolved solids — a noticeable benefit in Miami’s mineral-heavy water. It is the most accessible way for a Miami household to improve drinking-water quality at the point of use.

The limitations are well documented, and they are sharper here than elsewhere. Because Miami’s water is so high in dissolved solids, the five-stage filters exhaust quickly, so replacement frequency — and cost — runs higher than a Brita-class pitcher. And because it strips nearly everything, including minerals, the output tastes flat to many people; some find it slightly metallic. A filter a household won’t drink from is not protecting anyone, so taste preference is worth testing before committing.

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How to Test Your Miami Tap Water

A countywide report is an average across hundreds of monitored points. It cannot tell you whether the specific pipe feeding your home contributes lead, or what your particular wellfield-fed neighborhood looks like for byproducts — and those are among the most useful things you can learn about your water. WASD provides water quality information to its customers, which is a reasonable first reference.

For a fuller picture, an independent laboratory test characterizes your tap specifically. Get a Tap Score Test — its mail-in kits cover lead, disinfection byproducts, hardness, and the broader contaminant panel, and the results arrive in a format you can act on. Our guide on how to test your water at home explains how to read what comes back. Testing before you buy is the difference between choosing a filter for your actual water and guessing.

Frequently Asked Questions

Is Miami tap water safe to drink?

By federal standards, yes — Miami-Dade’s most recent report met every enforceable EPA limit, including for disinfection byproducts, lead, and radium at the system level. The qualifiers are the byproducts and the service line. The city’s haloacetic acids run close to the federal limit and well above health-based guidelines, and lead can enter from aging plumbing the countywide average does not reflect. For older homes and for households concerned about byproducts, testing and point-of-use filtration are reasonable precautions.

Does Miami water have PFAS?

Earlier monitoring reported PFOS and PFOA above the EPA’s 2024 federal limit of 4 ppt for each compound, and these detections are consistent with the shallow Biscayne Aquifer’s vulnerability to surface contamination. Monitoring under the new federal rule is ongoing, and utilities have until the compliance deadline to meet the standard. If PFAS is your specific concern, a reverse osmosis system or a PFAS-certified carbon filter addresses it.

How hard is Miami water?

Very hard — roughly 22 grains per gallon, or about 383 mg/L as calcium carbonate, owing to the limestone Biscayne Aquifer. That is among the hardest tap water of any major US city. It leaves significant scale on fixtures and in water heaters, spots glassware, and reduces soap performance, which is why a whole-house softener is a reasonable consideration for many Miami households.

Do I need a water filter in Miami?

For drinking water, an NSF 53 carbon filter or a reverse osmosis system is worth considering specifically for the disinfection byproducts that are Miami’s most consistently elevated contaminants — and reverse osmosis also addresses PFAS and radium. Separately, the city’s very hard water leads many households to add a whole-house softener for scale control. Test first, then match the treatment to what you find and what bothers you most.

Sources Cited

EWG Tap Water Database — Miami-Dade Water and Sewer (PWS ID FL4130871): https://www.ewg.org/tapwater/system.php?pws=FL4130871
Miami-Dade Water and Sewer Department — Water Quality Report (most recent Consumer Confidence Report)
U.S. EPA, Safe Drinking Water Information System (SDWIS) and 2024 PFAS National Primary Drinking Water Regulation
U.S. EPA — Lead and Copper Rule and Radionuclides Rule
Florida Department of Environmental Protection — Biscayne Aquifer drinking water supply

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