Does water work during a power outage? City taps, wells and the first hour

Whether your taps keep running depends on where your water comes from, and the first twenty minutes decide how much of it you keep.

By the OFF Grid Journal staff · October 8, 2026 · 6 min read
Based on Chapter 0, The First-Hour Plan of The Off-Grid Handbook by Garrett Dalton

It depends on where your water comes from. On a private well, the water stops when the power does, because the well pump runs on household electricity and only what is left in the pressure tank reaches the faucet. On city water, the taps usually keep running at first, but pressure can fall if the utility's pumps lose power, and a loss of pressure is often followed by a boil water advisory.

Either way, the right move is the same: fill the bathtub and every clean container in the first minutes, while you still have pressure. The Off-Grid Handbook puts it in one line: water pressure that fills a bathtub in minute ten is gone by hour three.

Does water work during a power outage? The short version

Well pump in a power outage: why the taps go dry

A private well has no water tower behind it. The pump fills a pressure tank, and the tank feeds your faucets until its pressure runs down. When the power goes out, nothing refills it.

What you have left is the water in the tank, the pipes and the water heater. That is not much, so stop running taps for anything but essentials the moment the lights go out.

CDC says a generator can run a well pump where appropriate, but a licensed well contractor, electrician or power company should size it so the pump is not damaged. Any generator runs outdoors only, at least 20 feet from the house and never in a garage, even with the door open. Our guide on why a generator never belongs in the garage explains the carbon monoxide risk.

When the power comes back, CDC advises checking whether the well lost pressure, even if everything seems normal. If it did, or if there was flooding, ask your local health department about testing the water before you drink it.

City water pressure in a power outage

Municipal systems keep treated water in storage tanks and towers, which is why city taps often keep running when the lights go out. That buffer is not unlimited. FEMA notes that when drinking water pumps and their electrical controls lose power, service is often disrupted.

Pressure matters for safety as well as convenience. According to FEMA, a loss of system pressure can let ground water and floodwater into the pipes, which is why pressure loss often leads to a boil water order until the system is disinfected.

Ready.gov's advice for any outage is short: pay attention to water advisories, and boil water or use your stored supply if needed. CDC adds that water treatment may not be working fully during an outage, so bottled, boiled or treated water is the safe choice for drinking, cooking and hygiene.

Should you fill the bathtub before a storm?

Yes. A full tub is the cheapest water storage in the house, and the Handbook makes it the third action of its first-hour triage, right after people and hazards. A tub holds 40 to 60 gallons, according to the book.

Treat tub water as wash and flush water. An ordinary bathtub is not a clean drinking container, so disinfect any tub water before anyone drinks it, using the method in how to purify water with bleach. Project 11 of the book adds a food-safe tub liner and a squeeze-bulb siphon to a small kit for exactly this job.

To flush a toilet without running water, the book says to pour 1.5 to 2 gallons straight into the bowl, not the tank. Used wash water does the job fine, which is the idea behind a simple greywater loop.

What to do in the first 20 minutes

Chapter 0 of The Off-Grid Handbook, The First-Hour Plan, sets out a six-line triage block designed to be finished in about 20 minutes:

1. People: everyone accounted for and unhurt.
2. Hazards: a fast walk-down for gas smell, water where it should not be, electrical damage and structural surprises.
3. Water: fill the bathtub and every container while pressure lasts.
4. Cold: refrigerator and freezer doors shut, the outage start time written on the door in marker, and the doors stay shut.
5. Light and information: lights up, battery radio on, phones to low-power mode.
6. Agreement: sixty seconds, everyone together, on what is known and what happens next.

The start time on the fridge door matters because food safety runs on the clock. CDC says a closed refrigerator keeps food safe for up to 4 hours and a full freezer for about 48 hours, and our guide to how long food lasts in the fridge without power covers what to keep and what to throw out.

Households that drill the block routinely finish in under fifteen minutes, the book says. Project 61 turns it into a laminated card with a named owner for every line, and the rest of the hour is laid out in what to do when the power goes out.

Water you already have in the house

Before you open a stored jug, use what is already in your plumbing. EPA lists melting ice cubes and draining the water heater or the pipes as emergency sources of water inside the home.

If you drain the water heater, turn off its electricity or gas first and let the water cool. Draw it from the drain valve at the bottom into a clean container.

A rain barrel keeps working in a blackout because it runs on gravity. Its water is fine for flushing, washing and the garden, but it is not drinking water until it has been filtered and disinfected.

How much water to store for a power outage

The baseline from CDC and Ready.gov is one gallon per person per day, with at least three days on hand and two weeks as the better target. For a household of four, that is 12 gallons for three days and 56 gallons for two weeks.

The bathtub buys time, but it does not replace a dated, rotated store of clean water. Our guide to how much water per person per day covers containers and rotation, and Project 5 of the book sets up the whole store in about an hour.