Skip to main content
U.S. flag

An official website of the United States government

Here’s how you know

Dot gov

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

HTTPS

Secure .gov websites use HTTPS
A lock (LockA locked padlock) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

    • Environmental Topics
    • Air
    • Bed Bugs
    • Cancer
    • Chemicals, Toxics, and Pesticide
    • Emergency Response
    • Environmental Information by Location
    • Health
    • Land, Waste, and Cleanup
    • Lead
    • Mold
    • Radon
    • Research
    • Science Topics
    • Water Topics
    • A-Z Topic Index
    • Laws & Regulations
    • By Business Sector
    • By Topic
    • Compliance
    • Enforcement
    • Laws and Executive Orders
    • Regulations
    • Report a Violation
    • Environmental Violations
    • Fraud, Waste or Abuse
    • About EPA
    • Our Mission and What We Do
    • Headquarters Offices
    • Regional Offices
    • Labs and Research Centers
    • Planning, Budget, and Results
    • Organization Chart
    • EPA History

Breadcrumb

  1. Home
  2. Ground Water and Drinking Water

Managing Cyanotoxins in Public Drinking Water Systems

Cyanobacteria bloom

Cyanobacteria, formerly referred to as blue-green algae, are found naturally in lakes, rivers, ponds and other surface waters. When certain conditions exist, such as in warm water containing an abundance of nutrients, they can rapidly form harmful algal blooms (HABs). Some HABs are capable of producing toxins, called cyanotoxins, which can pose health risks to humans and animals through drinking water and recreational water exposure. Additionally, HABs can create taste and odor problems in drinking water, which do not have adverse human health impacts but can create an earthy and musty taste and smell.

Related Information

  • Managing HABs in Surface Water
  • Managing Algal Toxins in Drinking Water
  • Managing Algal Toxins in Recreational Waters

Conventional water treatment (consisting of coagulation, sedimentation, filtration, and chlorination) can generally remove intact cyanobacterial cells and low levels of cyanotoxins from source waters. However, water systems may face challenges in providing drinking water during a severe bloom event when there are high levels of cyanobacteria and cyanotoxins in source waters.

With proactive planning, diligent operations and maintenance, and active management, public water systems can reduce the risks of cyanotoxins breaking through the treatment process and occurring in finished drinking water. This page contains information on public water systems to assist in managing cyanotoxin risks in drinking water. For more information on cyanobacterial HABs in ambient water, including cyanotoxins in recreational water, click here.

Learn about available tools to support proactive planning for cyanotoxin management by watching this video:

  • Basic Information on Cyanobacteria and Cyanotoxins
  • Harmful Algal Blooms and Cyanotoxins in Drinking Water: Factsheets and FAQs
Follow these links to find tools, health-related information, and EPA's efforts to address cyanotoxins in drinking water:
  • What cyanotoxin management tools are available for public water systems?
  • What are the health risks associated with cyanotoxins in drinking water?
  • How is EPA addressing cyanotoxins in drinking water?

Ground Water and Drinking Water

  • Basic Information
  • Private Wells
  • Consumer Confidence Reports
  • Regulatory Requirements
  • Standards and Regulations
  • All Drinking Water Topics
  • Safe Drinking Water Information System
  • For Students and Teachers
Contact Us about Ground Water and Drinking Water
Contact Us to ask a question, provide feedback, or report a problem.
Last updated on February 20, 2025
  • Assistance
  • Spanish
  • Arabic
  • Chinese (simplified)
  • Chinese (traditional)
  • French
  • Haitian Creole
  • Korean
  • Portuguese
  • Russian
  • Tagalog
  • Vietnamese
United States Environmental Protection Agency

Discover.

  • Accessibility Statement
  • Budget & Performance
  • Contracting
  • EPA www Web Snapshot
  • Grants
  • No FEAR Act Data
  • Plain Writing
  • Privacy
  • Privacy and Security Notice

Connect.

  • Data
  • Inspector General
  • Jobs
  • Newsroom
  • Regulations.gov
  • Subscribe
  • USA.gov
  • White House

Ask.

  • Contact EPA
  • EPA Disclaimers
  • Hotlines
  • FOIA Requests
  • Frequent Questions
  • Site Feedback

Follow.