Water — Track 1: Know Your System
Your home's water infrastructure is the foundation of your preparedness. Knowing where every shutoff is, what your water heater holds, and how your system responds to a power outage takes an hour. Not knowing it in a burst pipe or outage scenario costs significantly more than that.
Two systems
How it works, what it needs, where it fails
Municipal water travels from a water treatment plant through underground distribution mains to your home's service line, through the water meter, and into your household plumbing. Treatment happens upstream — your tap delivers finished drinking water.
What it needs: Continuous pressure from the distribution system (maintained by pumps and elevated tanks). Power outages at pumping stations reduce pressure; major main breaks lose it entirely.
Where it fails: Main breaks, contamination events requiring boil water advisories, infrastructure damage from disasters, and water treatment plant disruptions. Municipal water is reliable for years and then stops without warning.
Your role: Know where your meter is, what your service line pressure is, where your main shutoff is, and how to read a water quality notice. The utility handles treatment — you handle storage.
Independent supply, single point of failure
Well water travels from an aquifer through a drilled casing, up through a submersible pump, into a pressure tank, and into your household plumbing. Your property is a complete water system — you own the infrastructure and are responsible for its quality.
What it needs: Electricity. The submersible pump runs on power. No power means no water — there is no residual pressure reserve beyond the pressure tank's capacity (typically 5–10 gallons of usable water).
Where it fails: Power outages are the primary vulnerability. Secondary failures: pump failure, pressure tank failure, drought reducing the aquifer, flooding contaminating the well, and annual maintenance gaps that allow bacterial growth.
Your role: Backup power or backup pump. Test annually. Know where all components are. See the Well Water Preparedness guide.
The main shutoff
The main water shutoff stops all water flow to your home. In a burst pipe, this is the valve that limits thousands of dollars of damage. Most homeowners find it for the first time during a plumbing emergency. Find yours before that happens.
Homes with basements
Look near the front foundation wall in the direction of the street. The main water line enters the house low on the wall — the shutoff is typically within a few feet of where it enters. Often near the water meter.
Homes on a slab (no basement)
Check the utility or mechanical room (near the water heater), the garage, or a utility closet. In warm climates, it may be outside in a ground-level box near the water meter. Look for a metal plate or box flush with the ground near the street.
Condos and apartments
Your unit shutoff is typically under the kitchen or bathroom sink, behind the toilet, or in a utility closet. The building main shutoff is controlled by building management — know who to call for a building-wide shutoff.
Valve types — how to operate each
Ball valve (lever handle)
The fastest and most reliable valve type. The lever is parallel to the pipe when open, perpendicular when closed. A 90-degree turn closes it completely. Modern homes typically have ball valves — confirm yours is not corroded open.
Gate valve (round wheel handle)
Older homes often have gate valves — a round wheel handle you turn multiple times. Clockwise to close (righty-tighty). Gate valves can seize if not operated regularly. Turn yours once a year to prevent it from freezing in place.
Street-side curb shutoff
The valve at the street-level meter box requires a curb key (also called a meter key) — a long T-shaped tool. Available at hardware stores for a few dollars. Keeps a curb key with your emergency supplies so you or a plumber can access the street-side shutoff.
Label it
Once you locate every shutoff, label it. Waterproof valve tags or adhesive labels are inexpensive. Label includes: valve name, open/close direction, and the date you verified it works. Anyone in your household — or a plumber, housesitter, or tenant — should be able to find and operate the shutoff without hunting for it.
Appliance shutoffs
Isolating one appliance without shutting off the whole house is often the fastest response to a failure. These shutoffs are behind or under the appliance — find yours now.
Cold water inlet valve at the top of the tank. Typically a gate or ball valve on the cold supply pipe. Shutting this off stops water entering the tank. Also the first step before draining the tank for emergency water access. Know where the power cutoff (electric) or gas shutoff (gas) is too.
Location: top of the water heater on the cold-water side (usually the right side).
An oval or football-shaped shutoff valve behind the toilet near the floor on the supply line. Turn clockwise to close. Shutting this off stops water entering the tank — useful if the fill valve fails or the tank overflows. Test it annually to ensure it's not seized.
Location: low on the wall behind the toilet, on the water supply line.
Under-sink shutoffs on both the hot and cold supply lines — small valves on the flexible hoses. Shutting these off isolates the fixture for faucet replacement or a failed sprayer hose. In an emergency, under-sink shutoffs also give you a local collection point.
Location: inside the cabinet under each sink, on the supply lines running up to the faucet.
Hot and cold supply valves behind the washing machine — typically two hose bibb-style valves (turn clockwise to close). Water supply hoses are one of the most common household flood sources. These valves should be turned off when you're away for more than a day.
Location: wall behind the washing machine, on the hot and cold supply lines.
A small saddle valve or inline valve on the cold water supply line running to the refrigerator — typically in the cabinet behind, under, or beside the fridge. If the ice maker line fails (a common source of slow water damage), shutting this off stops the damage.
Location: under the cabinet near the refrigerator, or behind the fridge where the supply line connects.
Most hose bibs have an interior shutoff on the supply pipe — important to turn off in winter to prevent freeze damage. Frost-free sillcocks have a built-in shutoff that extends back inside the wall. Know which type you have and where the interior shutoff is if your hose bib needs to be isolated.
Location: inside the house on the pipe feeding the exterior bib, often in the basement or crawl space directly inside.
Emergency reserve
A standard residential tank water heater holds 30 to 80 gallons of treated municipal water — the same water that comes from your tap, kept warm. Most 40-gallon tanks provide about 35 usable gallons after sediment at the bottom. This is often the single largest overlooked water source in a household — larger than most people's stored supply.
The key is knowing how to access it before you need it. The steps are simple but require knowing the location of three components: the power or gas shutoff, the cold-water inlet valve at the top, and the drain valve at the base.
Tankless (on-demand) water heaters hold virtually no water reserve. This strategy applies to traditional tank heaters only. If you have a tankless heater, your water reserves come from storage containers and other sources.
Water heater access protocol
Annual maintenance that protects this reserve
Flush sediment annually
Sediment accumulates at the bottom of the tank over time. Flushing a few gallons from the drain valve once a year removes sediment, extends tank life, and ensures the first water from an emergency drain is cleaner. Label the tank with the last flush date.
Test the pressure relief valve
The pressure relief (T&P) valve is a safety device that vents if pressure or temperature exceed safe limits. Test it every 1–3 years by lifting the lever briefly. If it doesn't release water or drips constantly after testing, replace it.
Check the anode rod every 3–5 years
The anode rod protects the tank from corrosion. A depleted rod leads to tank rusting, reduced water quality, and early tank failure. Most homeowners never check it — extending your tank's life by 5–10 years is a reasonable outcome of doing so.
Every household and local water source — with yields and treatment requirements for each.
All sources →
Whole-house systems
A water softener uses ion exchange resin to remove calcium and magnesium (hard water minerals). It requires power for the automatic regeneration cycle and uses salt to recharge the resin.
During power outage
Water passes through unsoftened when the resin is exhausted. Most softeners have a bypass valve — route water around the unit to avoid issues if the resin is depleted or the unit is stuck in regeneration.
Emergency consideration
The bypass valve lets you skip the softener entirely. Locate it on the unit and know how to operate it. Hard water is safe to drink — softened water adds sodium and is not recommended for low-sodium diets or infant formula.
A whole-house filter installs on the main line and removes sediment, rust, and sometimes chlorine before water reaches your fixtures. These are passive (no power required) and continue functioning during outages.
During power outage
Continues filtering passively. If the filter cartridge is due for replacement, reduced flow rate may be noticeable. A clogged filter can also reduce household pressure significantly.
Emergency consideration
A whole-house sediment filter removes particles but does not disinfect. Under a boil water advisory, whole-house filtered water still requires boiling. Keep a spare filter cartridge on hand for rotation.
A well pressure tank stores a small volume of pressurized water so the pump doesn't have to cycle on for every small draw. A typical pressure tank provides 5–10 gallons of usable water before pressure drops below the cut-in point.
During power outage
The pressure tank provides 5–10 gallons before the well pump (which needs power) must run. After that, no more water without power or a backup pump.
Emergency consideration
Well owners need a power backup (generator) or a manual pump backup. The pressure tank's small reserve is for convenience, not emergency supply. See the Well Water Preparedness guide.
Wastewater
Wastewater flows from your home through a building drain to the municipal sewer main, then to a wastewater treatment plant. The system is gravity-fed from your home to the main — no power required on your end in most configurations.
During power outages: Usually continues functioning. The municipal wastewater infrastructure may have backup power for pump stations. Flushing is generally fine during typical outages.
Failure scenarios: Sewer main blockages, backups from flooding (when the system is overwhelmed), or long-term infrastructure failures. A sewer backup — when wastewater reverses from the main into your building drain — is a health emergency. Install a backwater valve if you're in a flood-prone area.
Wastewater flows to an underground tank where solids settle and separate. Liquid effluent flows by gravity to a drain field (leach field) where it percolates into the soil. Standard gravity-fed septic systems require no power to operate.
During power outages: Gravity septic systems continue functioning normally. If your system uses a pump (pressure-dosed or mound systems), power is required — know if your system has a pump.
Failure scenarios: Saturated drain field from heavy rain or flooding prevents percolation — toilets may back up or drain slowly. After a flood, do not use the septic system until the water table drops. Never run a generator exhaust near a septic system — carbon monoxide can enter through floor drains.
One-time audit
Walk through your home and complete this checklist once. After this, you know where everything is, everything is labeled, and you won't be searching during an emergency.
Shutoffs — locate and label each
Main water shutoff — indoor
Street-side curb shutoff (confirm you have a curb key)
Water heater — cold inlet valve, power/gas shutoff
All toilets — supply line shutoff behind each
Kitchen sink — hot and cold under-sink shutoffs
All bathroom sinks — under-sink shutoffs
Washing machine — hot and cold supply valves
Refrigerator ice maker line
Outdoor hose bibs and interior shutoffs
Water softener bypass valve (if applicable)
Know your system
Municipal or well water? (Confirm your source)
Tank or tankless water heater? (Tank = emergency reserve)
Water heater capacity (gallons — on the label)
Sewer or septic? (If septic: pumped or gravity?)
Water softener installed? (Locate bypass valve)
Whole-house filter? (Note cartridge size and replacement schedule)
Utility emergency number saved in phone
Know how to read your utility's online outage map
Subscribed to utility emergency alerts
Curb key in emergency supplies
Next steps
When your tap stops. The first-hour protocol — what to do, in what order, and when to escalate.
Action plan →
Container types, placement, rotation, and common mistakes. Build the supply your infrastructure can't guarantee.
Storage guide →
For the 43 million American households on well water. The electric pump is a single point of failure — here's how to address it.
Well owner guide →
The gear worth having
A curb key, valve tags, and a water leak sensor are inexpensive and prevent the most common household water disasters. The review page covers what to buy at each tier.