Miami-Dade County has 128 scored ZIP codes served mainly by 9 water utilities, 6 of which buy water from another system. Water Scores range from 49 to 63, with a median of 50. The contaminant most often above a published health guideline is Bromodichloromethane, in 9 of 9 utilities (EPA SDWA, EPA UCMR and Florida DEP data, 2020-2022).
Scored ZIP codes
128
Median Water Score
50Range 49 to 63
Above guideline, on average
4.9of 35.4 detected contaminants per ZIP code
Test data years
2016-2025EPA SDWA, EPA UCMR and Florida DEP data
Water Scores in Miami-Dade County
How many ZIP codes fall in each band. A higher score is better.
Strong 80-1000
Fair 60-796
Weak 40-59122
Low 0-390
Lowest: 33054 Opa-locka (49), 33014 Hialeah (50) and 33015 Hialeah (50). Highest: 33034 Florida City (63), 33239 Miami Beach (62) and 33141 Miami Beach (62).
Miami-Dade Water & Sewer Department → Town of Surfside → customers
Housing context
Across the 74 ZIP codes with housing data there are 1,009,138 housing units: 50.7% single-family homes and 42.6% in buildings of five or more units; 52.2% are owner-occupied. Source: Census ACS 5-year estimates, ACS 2024 5-year.
A legal limit and a health guideline are different
A legal limit is an enforceable standard, set by the EPA under the Safe Drinking Water Act. Limits weigh health research together with the cost and feasibility of treatment. A health guideline is published by public-health sources and based on health research alone. A utility can meet every legal limit and still be above a published health guideline.
Questions people ask
Which water utilities serve Miami-Dade County?
9 utilities are the main supplier for at least one scored ZIP code in Miami-Dade County. The largest by ZIP codes served: Miami-Dade Water & Sewer Department (99 ZIP codes), City of Hialeah (8 ZIP codes), City of Miami Beach (5 ZIP codes) and City of North Miami Beach (NMB Water) (5 ZIP codes). Source: EPA Water System Boundaries (CWS service area boundaries) v3.0, March 2026 release.
Which ZIP codes in Miami-Dade County have the lowest and highest Water Scores?
The lowest Water Scores are 33054 (49), 33014 (50) and 33015 (50). The highest are 33034 (63), 33239 (62) and 33141 (62). A score describes the utility's public test results for that ZIP code, not the water at any one tap (EPA SDWA, EPA UCMR and Florida DEP data, 2016-2025).
Which contaminants are most often above published health guidelines in Miami-Dade County?
Bromodichloromethane (above its guideline in 9 of 9 utilities, up to 277 times), Dibromochloromethane (above its guideline in 9 of 9 utilities, up to 125 times) and Chloroform (above its guideline in 9 of 9 utilities, up to 68 times). Source: EPA SDWA, EPA UCMR and Florida DEP data, 2016-2025.
Do any utilities in Miami-Dade County buy water from another system?
Yes. City of Hialeah buys from Miami-Dade Water & Sewer Department, City of Miami Beach buys from Miami-Dade Water & Sewer Department, City of Homestead buys from Miami-Dade Water & Sewer Department, City of North Miami buys from Miami-Dade Water & Sewer Department, City of Opa-locka buys from Miami-Dade Water & Sewer Department and Town of Surfside buys from Miami-Dade Water & Sewer Department. Source: EPA SDWA records, July to September 2026 extract.
How is the Water Score calculated?
The score starts at 100. It goes down 8 for each contaminant above a cited health guideline whose source states a cancer basis, 5 for each other contaminant above its cited guideline, 5 for each of PFOA and PFOS averaging above the 4.0 ppt limit in EPA's 2024 PFAS rule, 10 for each contaminant whose average of all samples is above EPA's legal limit (instead of its guideline step), and 1 for each contaminant with a cited cancer-based guideline that is detected below it. Only guidelines with a cited document count. The lowest score is 5. Higher is better.
What is the difference between a health guideline and a legal limit?
A legal limit is an enforceable standard, set by the EPA under the Safe Drinking Water Act. Limits weigh health research together with the cost and feasibility of treatment. A health guideline is published by public-health sources and based on health research alone. A utility can meet every legal limit and still be above a published health guideline.