How to Turn Off Utilities Before a Flood: A Room-by-Room Guide

Every minute you spend searching for a shutoff valve during rising floodwater is a minute you could have spent on higher-priority safety actions. Most homeowners cannot locate their main water shutoff without a search. Many don't know where their gas shutoff is. Fewer still know how to safely isolate their electrical panel from a flooded circuit. This guide solves that problem before a flood event: a comprehensive room-by-room walkthrough of every utility shutoff in a typical home — where to find it, how to operate it, what happens when you do, and what you should leave alone. Print this guide, keep it accessible, and mark your shutoff locations during clear weather so you don't have to find them in an emergency.

Before you start: utility shutoff location map

The first step is to create a shutoff location map for your specific home. Walk through your house and identify the following locations, mark them on a simple floor plan or photograph them with your phone, and note the operating instructions for each. Store this information in a location accessible to all household members.

Tools you'll need: A pair of slip-joint pliers for stubborn valves, a pipe wrench for the main water shutoff (if it hasn't been operated recently), a flashlight for low-light conditions, and a non-sparking tool (plastic or wood-handled) for gas shutoffs if you need to operate one in wet conditions.

For each utility, know these four things before a flood event: 1. Where is it? Exact location — not "in the basement" but "on the right side of the water heater, second shelf up." 2. How do I operate it? Clockwise/counterclockwise, tool required, number of turns. 3. What does it control? Everything in the home, or just one appliance? 4. Who should I call if I'm not sure? Plumber for water/gas, electrician for electrical, utility emergency line for mains.

Basement and mechanical room: main utility shutoffs

The basement or mechanical room typically houses the most critical utility shutoffs. These should be your first priorities in pre-flood preparation.

Main water shutoff (entire house). The main water shutoff is the valve that stops all water flow into your home — from the municipal supply or well. In most homes, it's where the water service line enters: typically near the front foundation wall of a basement, adjacent to the water meter, or in a utility closet. Older homes may have a gate valve (round handle); newer homes typically have a ball valve (lever handle). Gate valves can seize from disuse — test yours annually and replace with a quarter-turn ball valve if it won't move freely. To shut off: for a ball valve, turn the lever 90 degrees so it's perpendicular to the pipe. For a gate valve, turn clockwise until firm resistance. Shutting off the main water stops all water supply — including to fire sprinkler systems if your home has them, so confirm your sprinkler system has a separate shutoff before relying on the main water shutoff as your only option. Browse main water shutoff valves on Amazon.

Main gas shutoff (at the meter). The natural gas main shutoff is at the gas meter — usually on the outside of the house near where the service line enters. The valve is typically a metal handle on a brass fitting. To shut off: use a wrench (adjustable or pipe wrench) to turn the handle one-quarter turn so it's perpendicular to the pipe. This stops all gas flow into the home. For propane, the main shutoff is at the tank itself — the large brass or steel valve on top of the tank. In both cases, after shutting off the main, no gas appliances in the home will function until service is restored by a professional.

Main electrical panel (load center). The main electrical panel (breaker box) is typically in the basement, a utility closet, or a garage. The main breaker (usually a double-pole breaker at the top of the panel, 100–200 amps) controls all power to the home. To shut off: flip the main breaker to the OFF position. This cuts power to all circuits. Note: the main breaker does not shut off power coming FROM the utility — the service entrance wires are still live even with the main breaker off. Only a licensed electrician or the utility company can de-energize the service entrance. In a flood scenario, turning off the main breaker prevents your home's wiring from carrying floodwater-conducted electricity to outlets and fixtures throughout the house.

Kitchen: gas and water shutoffs for kitchen appliances

The kitchen contains multiple utility connections, each with individual shutoffs that should be located and operated before flooding.

Gas range/oven shutoff. Every gas appliance has its own shutoff valve — you should not need to shut off the main gas to turn off a single appliance. The gas shutoff for a range is typically in the cabinet below the range, where the gas supply line enters from the floor or wall. It's a small valve (often a brass valve with a flat handle) that supplies the range directly. To shut off: turn the handle so it's perpendicular to the pipe. Confirm by checking that the igniter no longer produces a flame. After a flood, do not reconnect the range until the gas line has been inspected and the appliance has been checked for water damage.

Refrigerator water line shutoff. Many refrigerators with ice makers and water dispensers have a dedicated water supply line with a shutoff valve. This is typically under the kitchen sink or behind the refrigerator, connected to a small diameter copper or plastic line. Turn the valve clockwise to shut off water to the refrigerator. If your refrigerator doesn't have a dedicated shutoff, shutting off the main water supply will stop water to the refrigerator — but this is less precise.

Dishwasher supply line. The hot and cold water supply lines to the dishwasher typically connect at a water valve under the kitchen sink. Locate the valves that supply the dishwasher (usually a small valve on the hot water supply line under the sink) and turn them off. This prevents a supply line failure from flooding the kitchen.

Laundry room: washer and dryer utility shutoffs

The laundry room is one of the most common sources of household flooding — and the most preventable. Every washing machine should have accessible shutoff valves.

Washing machine water supply valves. Behind or beside every washing machine, there are two valves (hot and cold) controlling the water supply. These should be closed when the washer is not in use — particularly before a flood. Turn both handles clockwise until firmly closed. If the valves are difficult to operate, replace them before the flood season with quarter-turn ball valves, which are more reliable and faster to close in an emergency. After closing the supply valves, disconnect the hoses from the machine (or at least confirm they're tightly connected) — even with the valves closed, pressure on the hose connection can cause leaks.

Gas dryer shutoff. If you have a gas dryer, there is a gas shutoff valve near the dryer — typically behind or beside the appliance, where the flex gas line connects. Turn it perpendicular to the pipe to close. If you have an electric dryer, turn off the circuit at the electrical panel (a dedicated 30-amp circuit for the dryer) — this both protects the dryer from flood damage and prevents it from being a hazard when power is restored.

Utility sink connections. If your laundry room has a utility sink, the drain connections and any hot/cold supply valves should be assessed. Utility sink drain connections can backflow during flooding if the municipal drain system is overwhelmed — a backwater valve on the sink drain prevents this. See our guide on backflow prevention for floods.

Water heater: the most critical appliance shutoff in a flood zone

The water heater requires specific gas and water shutoff procedures that differ from other appliances. Getting these wrong can create both flood damage and safety hazards.

Gas water heater: shut off gas first, then water. For a gas water heater, the sequence matters. First: turn the gas shutoff valve on the gas supply line to the heater (the small valve on the flex connector or supply pipe). Turn it perpendicular to the pipe. This stops gas flow to the burner and pilot light. Second: turn off the cold water inlet valve at the top of the water heater (the valve on the pipe leading into the tank). This stops water from entering the tank. Do not drain the tank — a full tank is heavier and more stable during flooding, and draining a gas water heater in a flood zone is not necessary for flood protection (only for freeze protection, which is a separate concern). After the flood, do not restore gas or water to the water heater until it has been professionally inspected.

Electric water heater: shut off power first, then water. For an electric water heater, the procedure is different: first, turn off the circuit breaker that supplies the water heater (usually a 30-amp double-pole breaker in the main panel). Confirm power is off by testing with a voltage tester or checking that the upper and lower heating elements are not energized. Second: shut off the cold water inlet valve at the top of the tank. Do not drain the tank until after professional inspection — a full tank is more stable and less likely to be damaged by debris impact during flooding.

What NOT to turn off during a flood

Some shutoffs should be left alone during a flood event, either because operating them creates greater hazards or because they're outside your control.

Do not turn off your well pump at the pressure tank. If your home uses a private well, the pressure tank and pump controls are in the basement or pump house. Turning off the pump at the pressure tank switch may not stop water flow into the home — the underground well head may still be submerged and flooding the system from below. If you have a well, contact a pump professional or the county extension office for specific shutoff procedures.

Do not attempt to shut off the utility company's main line. The gas meter main shutoff and the electric service entrance at the transformer are utility company equipment. Attempting to operate these creates safety hazards and may be illegal. Shut off at the house-side valves only.

Do not turn off fire sprinkler system shutoffs unless you are certain they are separate from the main water supply. Many residential fire sprinkler systems are connected to the main water supply. Shutting off the main water supply to prevent flood damage will also disable the sprinkler system. Know where your sprinkler system shutoff is — it may be a separate valve with its own dedicated supply — before a flood event.

Re-entry checklist after a flood

Before re-entering your home after a flood, confirm the following utility-related safety conditions:

Electrical safety. Do not enter the home if you can hear buzzing, crackling, or other electrical sounds. If the main breaker was on during flooding, assume the panel is compromised. Do not reset any breakers until the panel has been inspected by a licensed electrician. If you smell burning plastic or insulation, leave immediately — this indicates arcing or electrical fire.

Gas safety. Before re-entering, if you shut off gas before the flood, check whether the gas shutoff is still closed. Open doors and windows before attempting to use any gas appliances. If you smell gas at any time, leave immediately and call 911 and your gas utility emergency line. Do not operate any electrical switches if you smell gas.

Water safety. Do not drink tap water until local authorities confirm it is safe — flooding can contaminate public water supplies. Do not flush toilets or use any connected water fixtures until the main water shutoff is confirmed intact and municipal water authorities have cleared the supply.

Frequently Asked Questions

What is the first utility to shut off during a flood?

The gas supply is typically the first utility to shut off during a flood — before water or electricity. A flooded gas appliance creates an immediate explosion and fire risk. The gas main shutoff at the meter takes priority over everything else. Turn off the main gas valve first (perpendicular to the pipe), then shut off the main water supply, then turn off the main electrical breaker. If you are uncertain about operating the gas shutoff (old valve, stuck, wrong tool), evacuate and call your gas utility emergency line. Do not risk delay if the valve is difficult — evacuate and let professionals handle it.

Should I turn off my water heater before flooding?

Yes — turn off your water heater before flooding, but the procedure depends on whether it's gas or electric. For a gas water heater: first, turn off the gas shutoff valve on the supply line to the heater. Second, turn off the cold water inlet valve at the top of the tank. Do not drain the tank — a full tank is more stable during flooding. For an electric water heater: first, turn off the dedicated circuit breaker in the main panel. Second, turn off the cold water inlet valve. Do not drain until after professional inspection. After a flood, do not restore gas, water, or power to the water heater until a licensed plumber has inspected it — a submerged water heater requires replacement, not repair.

How do I turn off electricity in a flooded basement safely?

If your main electrical panel is in a flooded area and you can access it safely, turn off the main breaker (the double-pole breaker at the top of the panel) by flipping it to OFF. This cuts power to all circuits in the home and prevents the flooded wiring from conducting electricity throughout the house. Important: the service entrance wires at the top of the panel remain energized from the utility — turning off the main breaker protects downstream circuits but does not de-energize the service entrance. If the panel is underwater, do not attempt to operate it — water and electricity in combination create lethal conditions. Evacuate and call the utility company to disconnect service from the transformer.

Should I shut off my main water supply before a flood?

Yes — shutting off the main water supply before a flood prevents floodwater from being forced through your plumbing system in reverse (backflow), which can introduce contaminated floodwater into your supply pipes and fixtures. It also prevents a burst pipe or failed water heater from flooding your home during the event if you are away. The main water shutoff is typically at the point where the water service line enters the house — usually near the water meter in the basement. Locate it in advance, ensure the valve operates freely (replace seized gate valves with quarter-turn ball valves), and have a pipe wrench available if it's stiff. After shutting off, open a faucet at the lowest level of the house to relieve pressure in the system.

What utilities should I NOT shut off during a flood?

Do not attempt to shut off utility company equipment: the gas service regulator, the electric service entrance at the transformer, or any utility-owned infrastructure. Do not shut off fire sprinkler system supply valves unless you are certain the sprinkler system has a dedicated shutoff separate from the main water supply — shutting off the main water supply will disable your sprinkler system. Do not shut off a well pump at the pressure tank unless specifically instructed by a pump professional for your system. When in doubt about any utility shutoff, call the appropriate professional.