Largo, Florida

Largo, Florida Largo, Florida

What is the Water Quality in Largo, Florida?

[Updated: June 13, 2023]

Compared to other US cities, Largo water quality ranks in the middle range for contamination excluding Lead.

Most of the 18 contaminants have cancer-causing attributes.

  • Arsenic is at very high levels: 54x health guidelines.
  • Haloacetic acids (HAA5) are at extremely high levels: 253x health guidelines.
  • Haloacetic acids (HAA9) are at extremely high levels: 486x health guidelines.
    • These are both byproducts of the chlorine treatment process most water supplies go through.

Let’s look closer at what’s in Largo water.

What’s in Largo water?

Here are the top 5 chemical compounds in your water and what health issues they can potentially cause:

  1. Arsenic – Potential effect: Cancer
  2. Chlorate – Potential effect: Harm to the thyroid
  3. Haloacetic acids – Potential effect: Cancer
  4. Hexavalent Chromium – Potential effect: Cancer
  5. Total trihalomethanes – Potential effect: Cancer

These are five of the 18 contaminants analyzed by the Environmental Working Group (

6 of these contaminants are rated as exceeding EWG Health Guidelines.

Does Largo water have Lead contamination?

Yes, Largo has lead in its water. The most recent Lead samples collected in 2017 showed concentrations up to 1.6 parts per billion (ppb).

The legal limit for lead is 15 parts per billion. Being well-below this level is a good thing.

  • Concentrations between 3.8 ppb and 15 ppb put a formula-fed baby at risk of elevated blood lead levels. Read more about the symptoms of Lead in water.

There is no safe level of lead for humans.

  • The good news is that 99.99% of the lead can be removed.

See the What Can You Do? section below to learn how to filter out contaminants.

Where does Largo’s water come from?

Largo’s water comes from the Lake Seminole watershed.

All 22 EPA assessed water sources in the Lake Seminole watershed are in Impaired or Unknown condition. These include:

  • Allen Creek
  • Boca Ciega Bay
  • Bonn Creek
  • Cross Bayou Drain
  • Cross Canal
  • Direct Runoff to Bay
  • Direct Runoff to Intracoastal Waterway
  • Joe’s Creek
  • Lake Seminole
  • Lake Seminole Outlet
  • Long Bayou Runoff
  • Long Bayou/Cross Bayou
  • McKay Creek
  • Pasadena Lake
  • Pasadena Lake Outlet
  • Pinellas Park Ditches 1 and 5
  • Rattlesnake Creek
  • Sawgrass Lake
  • St. Joe Creek
  • Starkey Basin

Ideally, a water source would be rated in Good condition.

Whether a water source is in Impaired or Good condition refers to the quality of these uses:

  1. Drinking Water
  2. Aquatic Life
  3. Fish and Shellfish Consumption
  4. Recreation

Learn more from How’s My Waterway

See below for what you can do to improve Largo’s water.

Conclusion – What Can You Do?

Information about water quality in Largo can be surprising.

But there are things you can do in your home to clean up your water.

  1. Test Your Water using Varify Home Test Kits or similar.
  2. To Remove Lead and Other Contaminants In Your Home:
  • Use Activated Carbon filters to remove most contaminants in your drinking water.
    • Faucet-mount filters work better than pitchers.
    • PUR and Brita are low-cost and effective.
Brita Lead Filtration
Brita Faucet Mount – Amazon
Reverse Osmosis Systems
APEC System – Amazon

*Chlorination is an effective method of disinfecting/treating drinking water. You can then use a water filter to reduce the effects of chlorination byproducts to get the safest, cleanest water possible.

In Your Community:

Contact your local government officials and put pressure on them to invest in cleaner waterways and upgraded city water filtration and treatment.

Go to: to find contact information for your local officials.

Water Quality in Other Florida Cities

Florida Water Quality Page

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