Boil Water Notices in Houston: Why City Water Fails When the Power Does

Eduardo Donadi NetoEduardo Donadi Neto·
A large pot of water boiling on a stovetop range lit by a battery lantern during a Houston power outage.

Boil Water Notices in Houston: Why City Water Fails When the Power Does

The power went out Monday afternoon. Wednesday morning your phone buzzed with a message telling you to boil your water. The two events looked unrelated. They were the same event, seen from two utilities.

If you are on a private well, this is not your article. An outage there cuts your water instantly, and our guide on

Battery backup for a Houston well pump and water system→
covers it. This one is for the much larger group: households on City of Houston water, a municipal utility district, or a water supply corporation. You own no pump, and you assume the water question belongs to somebody else.

What follows: the mechanism, Houston's record, who loses pressure first, and an honest account of what a battery changes.

Key Takeaways

  • Texas requires public water systems to hold at least 35 psi throughout the distribution system under normal conditions and at least 20 psi during emergencies (30 TAC 290.46(r)). Fall below 20 psi and 290.46(q) makes a boil water notice the ordinary outcome.
  • The notice is precautionary and mandatory, not a contamination finding. Once pressure is lost, intrusion through leaks and joints cannot be ruled out (National Academies Press).
  • After Winter Storm Uri in February 2021, 2,038 Texas community water systems issued advisories lasting 1 to 36 days, and 85 percent of surveyed large urban utilities lost power (PLOS Water, 2023).
  • After Hurricane Beryl in July 2024, about 70 boil water notices covered Harris County systems and roughly 160 covered eight Southeast Texas counties (KHOU, 2024).
  • A home battery does not pressurize the city main and cannot prevent a citywide notice. It keeps your house working so you can live with one.
Check what a backup system would cover at your address→

Why does a power outage cause a boil water notice?

Because Texas sets a pressure floor and an outage pushes the system under it. Under 30 TAC 290.46(r), every public water system in the state must be operated to provide a minimum of 35 psi throughout the distribution system under normal operating conditions, and at least 20 psi during emergencies such as firefighting (Texas Administrative Code, Section 290.46).

Water reaches your tap through a chain of electrical equipment. Treatment plants clean it, high service pumps push it into the mains, booster stations move it across the grid, and water towers buy a few hours of gravity fed margin. Cut power and the system coasts on stored head, until it doesn't.

The 35 psi figure is the operating standard, not the trigger. The trigger sits lower: when distribution pressure drops below 20 psi, 290.46(q) sends the operator to a Texas Commission on Environmental Quality (TCEQ) decision flowchart, and a boil water notice is the ordinary outcome.

The reason it is mandatory rather than measured is the part nobody explains. A water main is not a sealed vessel. It sits in soil that also holds sewer lines and groundwater, and it leaks at joints and hairline cracks its whole service life. Under high internal pressure, those defects push water out. At zero or negative pressure, they can pull water in. The National Academies review of distribution system risk names leaks, cracks, submerged air valves and faulty seals as entry points (National Academies Press, 2006). Researchers assess that risk with hydraulic modeling rather than sampling, because measuring at the moment of the event is generally not possible (Besner, Prevost and Regli, Water Research, 2011).

So the notice does not mean your utility found something in the water. It means your utility briefly lost the ability to prove it didn't.

Texas minimum water pressure requirements: 35 psi under normal operating conditions, 20 psi during emergencies, 35 psi for affected utilities in Harris and Fort Bend Counties during an extended outage, and 20 psi for affected utilities elsewhere in Texas The Texas Pressure Floors 35 psi Normal operating conditions every public water system 20 psi Emergencies, such as firefighting every public water system 35 psi Extended outage, affected utility Harris and Fort Bend Counties 20 psi Extended outage, affected utility elsewhere in Texas 0 10 20 30 40 Minimum required pressure (psi)
Sources: 30 TAC 290.46(r); TCEQ Emergency Preparedness Plan requirements under Texas Water Code 13.1394.

Texas already anticipated this. Under Texas Water Code 13.1394, designated "affected utilities" must file an Emergency Preparedness Plan for holding pressure through a 24 hour outage, and TCEQ sets a higher bar inside Harris and Fort Bend Counties, 35 psi, than the 20 psi required elsewhere (TCEQ). Notices still happen by the dozen. The rule protects the system. Nothing in it protects your house.

What Houston's record actually looks like

Three events tell the story, and the middle one is the most instructive. During Winter Storm Uri in February 2021, 2,038 Texas community water systems issued boil water advisories covering more than 17 million people, and in a survey of large, mostly urban utilities, 85 percent lost power (PLOS Water, 2023). Power loss isn't a side effect of these events. It is the mechanism.

February 2021, Winter Storm Uri

Advisories lifted anywhere from 1 to 36 days later, mean 7.96 days. Small rural systems carried the longest, past 20 days in places, while large urban systems clustered at 5 to 7 days.

November 2022, one plant, one morning

Two transformers failed at Houston's East Water Purification Plant on Sunday morning, November 27, 2022. Pressure dropped below the 20 psi minimum and the City issued a boil water notice for its main system (Houston Public Media, 2022). It was not lifted until Tuesday morning, November 29, after laboratory samples cleared (Texas Tribune, 2022).

A brief electrical failure at one facility produced a notice that ran into a second day. Rescinding takes two things: pressure consistently held above 20 psi, and bacteriological samples showing no contamination. Restoring power satisfies the first. Only a lab satisfies the second. That is why the notice always outlives the outage.

July 2024, Hurricane Beryl

Beryl knocked out roughly 2.2 million CenterPoint customers at peak, more than 1 million were still out days later, and NWS heat indices ran 100 to 106 F through the restoration. By July 11, about 70 notices covered Harris County water systems (Community Impact, 2024) and roughly 160 were in effect across eight Southeast Texas counties (KHOU, 2024). Twenty were lifted days later once pressure returned and samples came back free of bacteria (Houston Chronicle, 2024).

For the wider picture, see

The full Houston power outage preparedness guide→
.

Horizontal bar chart of Texas boil water advisory durations during Winter Storm Uri: longest recorded 36 days, small rural systems about 20 days, statewide mean 7.96 days, large urban systems 5 to 7 days, shortest 1 day How Long Uri Advisories Lasted, by System Type Longest recorded 36 d Small rural systems 20+ d Statewide mean 7.96 d Large urban systems 5 to 7 d Shortest recorded 1 d 0 10 20 30 40 Advisory duration (days), February 2021
Source: PLOS Water, Tomko et al., "Disparities in disruptions to public drinking water services in Texas communities during Winter Storm Uri 2021," 2023.

Who loses water first, and why your floor matters

Water loss is not uniform across a city, and building height is the biggest single predictor of who notices first. A column of water costs roughly 0.43 psi per foot of rise, which is plain hydrostatics, not a study finding. A few dozen feet of height eats a real share of the required 35 psi.

A single story house on a slab is usually last to notice. It rides on whatever head the system still holds, which is why plenty of Houston homeowners sit through a long outage with the tap running normally.

A multi-story house or a building with a booster pump loses pressure almost immediately, because the pump doing the lifting sits on the same dead feeder as everything else. In-system boosting is common enough in Texas that TCEQ regulates it: a booster pump taking suction from the distribution system must hold at least 20 psi residual on the suction line at all times (30 TAC 290.44(d)(2)).

In an apartment or condo, the pump belongs to the building, not to you, and a battery in your unit does nothing for it. Our guide on

How battery backup works in Texas apartments and condos→
covers what a resident can control.

The honest boundary: what a home battery does not do

This is the part most backup power pages skip, so let's be flat about it.

A home battery does not pressurize the city main. It cannot push water into a grid it is not connected to. It cannot prevent, shorten, or exempt you from a boil water notice, because the notice covers a pressure zone, not a house. If your zone is under a notice, so is your tap, no matter what is running in your garage. And storing electricity does nothing to make water potable.

One narrow case runs the other way. If your home has its own booster pump on your own panel, that pump is a load like any other and a battery can carry it. You keep pressure at your fixtures. You still do not get water that is safe to drink while the zone is under a notice.

So here is the ranking, plainly. For a city water household, the water benefit of a home battery is secondary. The primary case is still cooling through a Houston summer and refrigeration for food and medication. Anyone selling it the other way around is overstating it.

Which leaves a better question: not whether a battery keeps your water clean, but whether it lets you live with the notice.

What a battery actually changes during a boil water notice

A boil water notice is a list of chores, and every one runs on electricity. CDC guidance is to bring clear water to a rolling boil for one minute (CDC). On an electric range with no power, that chore is simply impossible.

Boiling needs a working stove

An electric cooktop is how most Houston households would comply, and it is dead the moment the grid is. Our guide on

Running an electric range on battery backup→
walks through the load math.

Boiled water and food both need cold

A refrigerator holds a safe temperature about 4 hours, a full freezer about 48 hours, a half full freezer about 24 hours, doors kept closed (FoodSafety.gov). A two-day notice outlives both. See

How long food lasts in the fridge without power→
for the full timeline.

Stored water is the baseline either way

Ready.gov puts the planning figure at one gallon per person per day (Ready.gov). Your water heater is a reservoir too, and keeping that circuit alive means hot water for washing while ingestion is off the table. Water sits alongside the rest of the supplies in our

Power cut survival kit checklist→
.

Staying put is the real benefit

In the days after Beryl, the water question reached our team second, after the heat, and it arrived as confusion rather than fear. People asked why they were told to boil water they could not heat. A notice stacked on a multi-day outage in 100 to 106 F heat is what pushes a household out. Cool rooms and a cold refrigerator turn a two-problem emergency back into a one-problem inconvenience. If you do leave, our roundup of

Houston cooling centers and emergency resources→
lists where to go.

On sizing: one Eos smart controller delivers 11.5 kW continuous and 17.1 kW surge, and each module holds 9 kWh nominal, 8.76 kWh usable. The Plus configuration pairs two modules with one controller for 18 kWh nominal and 17.52 kWh usable, the tier that realistically carries cooling, refrigeration and a cooking circuit through a multi-day event.

See which system size fits your home→

Frequently asked questions

Does city water still work when the power goes out?

Often yes at first, then no. The system coasts on head stored in water towers and in the mains, so a single story house may never notice. Once the pumps are down long enough, pressure falls below the 20 psi threshold that triggers a notice, and service fails from the top down.

Why does a power outage cause a boil water notice?

Pumps stop, pressure drops below 20 psi, and 30 TAC 290.46(q) routes the operator to a TCEQ flowchart that ordinarily produces a notice. The trigger is a pressure reading, not a contamination test. At low or negative pressure, intrusion through leaks and joints cannot be ruled out.

How long does a Houston boil water notice last?

Longer than the outage that caused it. A notice lifts only once pressure above 20 psi is consistently maintained and bacteriological samples come back clean. In November 2022, a transformer failure at one Houston plant on a Sunday morning produced a notice that held until Tuesday morning (Texas Tribune, 2022).

Can a home battery keep my water running on city water?

Not the city's pressure. A battery cannot push water into a main it is not connected to. If your home has a booster pump on your own panel, a battery can run it and hold pressure at your fixtures. That still does not make water under an active notice safe to drink.

Is it safe to shower during a boil water notice?

Follow the exact wording of the notice your utility issued. Most restrict ingestion, which covers drinking, cooking, ice and brushing teeth, and address bathing separately. Your utility's instructions govern, because they reflect what happened in your pressure zone.

The bottom line

The power outage and the boil water notice are the same event, seen from two utilities. Three things to carry away:

  • The trigger is a pressure rule, a drop below 20 psi, not a lab result.
  • The notice outlives the outage, because lifting it takes restored pressure and clean lab samples.
  • A battery does not fix your water. It makes the notice survivable, by keeping the stove, the refrigerator and the air conditioning running while you wait it out.

For a city water home, that is the honest case: secondary on water, primary on heat and food.

Start your Houston backup plan→

Or call Eos at 833-989-3737 to talk through your setup with an installer.

Sources

This article explains why Houston-area power outages produce boil water notices and reflects Eos specifications as of August 2026. It is general information, not water safety guidance. Follow the instructions in the notice issued by your own water utility.

boil water noticepower outageHoustoncity waterwater pressurebattery backup