Short answer. In the United States, your water supplier must warn you within 24 hours when a problem could immediately affect your health, through TV, radio, newspapers, posted notices or direct delivery 1. FEMA's Ready.gov says to store at least one gallon of water per person per day for several days 3. If you drink from a private well, no government agency monitors it: test it yourself every year 7.
How do I know if my tap water is unsafe?
Your water supplier tells you. Under the federal Public Notification Rule, any situation that could immediately affect health triggers a "Tier 1" notice: suppliers have 24 hours to notify people who may drink the water, using media outlets such as television, radio and newspapers, public postings, personal delivery, or another method approved by the primacy agency 1. Problems that do not pose an immediate risk must be notified within 30 days 1.
Phaenyx found no national real-time list of boil water notices. Some state agencies publish their own: the Florida Department of Health, for example, keeps a list for Florida and says your utility or county emergency contact will have the latest information 8. Elsewhere, watch your supplier's channels and local media. Learn the difference between a boil water notice and a do-not-drink notice.
To know your water's normal quality, read your Consumer Confidence Report. Community water systems must send it each year by July 1; if you did not get one, call your supplier or use EPA's search tool 2. Our guide explains how to read a tap water quality report.
How much water should I store?
At least one gallon per person per day for several days, for drinking and sanitation 3. Children, nursing mothers and sick people may need more, and in very hot temperatures water needs can double 3. Buy bottled water and keep it sealed in a cool, dark place; water you bottle yourself should be replaced every six months 3. Never ration drinking water unless authorities order it 3. See U.S. emergency supplies, how much water per person and water storage containers.
If stored water runs out, Ready.gov calls boiling the safest treatment: a rolling boil for one full minute 3. More in how to purify water.
Is the United States short of water?
It depends on where you live. On the WRI Aqueduct 4.0 scale, the median U.S. city sits at "medium to high" baseline water stress, both today and in the 2050 business-as-usual projection, with "low to medium" drought risk 6. These are medians across U.S. cities, not a figure for your town.
Ready.gov says to always observe state and local restrictions on water use during a drought, and to contact your state or local government for current information 4. Phaenyx found no national register of watering restrictions. Drought.gov, run by NOAA, publishes current drought conditions 5. See our drought preparedness guide.
What if I drink from a private well?
You are on your own. CDC says the rules that protect public drinking water systems do not apply to privately owned wells, and that government officials do not regulate, treat or monitor them 7. Test your well at least once a year for total coliform bacteria, nitrates, total dissolved solids and pH, and again after nearby flooding or other problems 7. See private wells in an emergency and water after a flood.
Frequently asked questions
How fast must a water system warn me of a health risk?
Within 24 hours for a situation that could immediately affect health (Tier 1) 1.
How much water does FEMA say to store?
At least one gallon per person per day for several days, for drinking and sanitation 3.
When does my annual water quality report arrive?
Suppliers must send it each year by July 1 2.
How often should I test my well?
At least once a year, CDC says 7.
A household plan can record your supplier, where its notices appear and how much water you keep.
Sources
- U.S. Environmental Protection Agency (EPA) — Public Notification Rule — https://www.epa.gov/dwreginfo/public-notification-rule (accessed 2026-10-27)
- U.S. Environmental Protection Agency (EPA) — Consumer Confidence Report: information for consumers — https://www.epa.gov/ccr/ccr-information-consumers (accessed 2026-10-27)
- FEMA / Ready.gov — Water — https://www.ready.gov/water (accessed 2026-10-27)
- FEMA / Ready.gov — Drought — https://www.ready.gov/drought (accessed 2026-10-27)
- NOAA National Integrated Drought Information System (NIDIS) — Drought.gov — https://www.drought.gov/ (accessed 2026-10-27)
- World Resources Institute (WRI) — Aqueduct 4.0 water risk atlas, median of U.S. cities (CC BY 4.0) — https://www.wri.org/aqueduct (accessed 2026-10-27)
- Centers for Disease Control and Prevention (CDC) — Guidelines for Testing Well Water — https://www.cdc.gov/drinking-water/safety/guidelines-for-testing-well-water.html (accessed 2026-10-27)
- Florida Department of Health — Boil Water Notices — https://www.floridahealth.gov/community-environmental-public-health/emergency-preparedness-response/boil-water-notices/ (accessed 2026-10-27)
Turn this into action
Your plan for United States, worked out for your household.
- Water, food and equipment counted for each person and pet
- The nuclear plants and zones around your home
- Phaenyx Safe: one tap to tell your people you are safe
Sources
- U.S. Environmental Protection Agency (EPA) · Public Notification Rule checked 2026-10-27
- U.S. Environmental Protection Agency (EPA) · Consumer Confidence Report: information for consumers checked 2026-10-27
- FEMA / Ready.gov · Water checked 2026-10-27
- FEMA / Ready.gov · Drought checked 2026-10-27
- NOAA National Integrated Drought Information System (NIDIS) · Drought.gov checked 2026-10-27
- World Resources Institute (WRI) · Aqueduct 4.0 water risk atlas checked 2026-10-27
- Centers for Disease Control and Prevention (CDC) · Guidelines for Testing Well Water checked 2026-10-27
- Florida Department of Health · Boil Water Notices checked 2026-10-27