Maintenance procedure · Written to ASD-STE100 Issue 9 · Formatted to ANSI Z535

Find and Test the Main Water Shut-Off Valve

Locate the valve that stops water to the whole house, prove it still closes, and label it
ApplicabilityHouses and flats on a metered or well water supply with an indoor main shut-off valve
Task time24 min to 34 min editorial estimate, not a measurement
PersonnelOne
Revisionv2 · 2026-08-12
BEFORE YOU BEGIN

Before you begin. This procedure is general reference information, not professional advice. Equipment varies by manufacturer, model, and year. Always follow the documentation supplied with your equipment — where it differs from this page, follow the manufacturer. Verify that you have the tools, the working conditions, and the ability to do this task safely. If anything is unclear, if the equipment is damaged, or if the task exceeds your experience, stop and use a qualified professional. You are responsible for your own safety and for the outcome. This site accepts no liability for any loss, damage, or injury arising from the use of this information.

Specifications marked unverified could not be traced to a manufacturer source. Do not rely on them — obtain the value from your equipment documentation.

Summary

Every water emergency starts with the same instruction: turn off the water. That instruction assumes two things most households have never checked — that somebody knows where the main shut-off valve is, and that the valve still closes. Neither is safe to assume. FEMA's community preparedness handouts put "locate and label main water cutoff" on the outage checklist for exactly this reason, alongside a reminder to keep any special tool it needs stored nearby. A valve that nobody has turned in fifteen years is a valve nobody has proved.

This page is the half hour that decides how bad a burst hose or a split pipe gets. You find the valve, work out which of the two common types it is, close it, prove at a tap that the water really stopped, open it fully again, and then label it and tell the rest of the household. It does not cover replacing a valve, and it does not settle who may operate the valve in the box at the kerb — utilities genuinely disagree about that one. Seattle Public Utilities says plainly that older meters need a special tool and only its own crews operate them; DC Water publishes steps for lifting the cover and closing the valve itself. Ask yours. If your valve will not turn, this page tells you to stop, and why stopping is the right answer.

Necessary equipment

ItemNote
FlashlightUse the flashlight to see into a dark space.
ClothUse the cloth to dry the valve.
BucketPut the bucket below the valve before you turn the handle.
Label and a permanent markerAttach the label to the pipe near the valve.
Work gloves optionalThe gloves give a better grip on a wet handle.
Phone or paper optionalRecord the type of the valve and the date.

Find the Valve

Estimated 8 min to 15 min

NOTEThe valve is usually near the point where the water supply pipe enters the house.
CAUTION

LOOK INTO A DARK SPACE WITH A FLASHLIGHT BEFORE YOU PUT YOUR HAND INTO THE SPACE.
A spider or a sharp edge is a risk to your hand.

  1. Find the point where the water supply pipe enters the house.
    • A basement, a crawl space, a garage or a utility room is a common location.
    • In a warm climate the pipe can enter through an outside wall.
    • The pipe is usually the coldest pipe in the space.
    3m
  2. Examine that pipe for a valve with a handle.
    • The valve is usually the first valve on the pipe inside the house.
    • A water meter, if the meter is indoors, is usually near the valve.
    2m
  3. If you do not find a valve there, look near the water heater.
    • The pipe to the water heater comes from the main shutoff valve.
    2m
  4. If the property has a well, look at the well pump.
    • A well system usually has a valve on the pipe from the pump.
    2m

Identify the Type of the Valve

Estimated 2 min

NOTEThe shape of the handle tells you how many turns the valve needs.
  1. Look at the handle of the main shutoff valve.
    <1m
  2. If the handle is a straight lever, the valve is a ball valve.
    • A ball valve moves through a quarter turn from open to closed.
    • The lever is in line with the pipe when the ball valve is open.
    <1m
  3. If the handle is a round wheel, the valve is a gate valve.
    • You must turn the wheel of a gate valve many times.
    • The stem of a gate valve can rise out of the wheel as the valve opens.
    <1m
  4. Record the type of the valve and the location of the valve.
    1m

Close the Valve

Estimated 1 min to 3 min

Number of turns to close the valve
Unverified — do not rely on this value
COUNT THE TURNS ON YOUR OWN VALVE AND WRITE THE NUMBER ON THE LABEL

No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.

NOTICE

TELL THE OTHER PEOPLE IN THE HOUSE BEFORE YOU CLOSE THE MAIN SHUTOFF VALVE.
The valve stops the water at every tap in the house.

NOTICE

PUT THE BUCKET AND THE CLOTH BELOW THE MAIN SHUTOFF VALVE BEFORE YOU TURN THE HANDLE.
An old valve can leak at the stem.

NOTICE

DO NOT USE FORCE ON THE HANDLE OF THE MAIN SHUTOFF VALVE.
Force can break an old valve and cause a flood.

NOTICE

DO NOT TURN A HANDLE THAT YOU CANNOT SEE FULLY.
A hidden handle can be the handle of a different valve.

  1. Turn the handle of the main shutoff valve to the closed position.
    • Turn the handle clockwise.
    • Turn a lever handle through a quarter turn, until the lever is across the pipe.
    • Turn a wheel handle until the wheel stops.
    • Count the turns of a wheel handle and record the number.
    <1m
  2. Stop the work if the handle does not move with light hand pressure.
    • A valve that does not move is a job for a plumber.
    <1m
  3. Look at the stem of the valve for water.
    • A wet stem is a sign of worn packing.
    <1m

Prove That the Water Stopped

Estimated 3 min

  1. Open a cold water tap on the lowest floor of the house.
    1m
  2. Look at the flow from the tap.
    • The water in the pipe above the tap flows out first.
    • The flow then decreases to a drip and stops.
    1m
  3. If the flow stops, the valve closes correctly.
    <1m
  4. If the flow continues, the main shutoff valve does not close fully.
    • A valve that does not close fully is not a safe valve in an emergency.
    • Speak to a plumber about a valve that does not close fully.
    <1m

Open the Valve Again

Estimated 3 min to 5 min

NOTICE

TURN THE HANDLE SLOWLY WHEN YOU OPEN THE MAIN SHUTOFF VALVE.
Water pressure that increases quickly can cause damage to the pipes.

NOTICE

OPEN THE MAIN SHUTOFF VALVE FULLY AFTER THE TEST.
A valve that stays partly closed decreases the flow at every tap.

  1. Turn the handle of the main shutoff valve to the open position.
    • Turn the handle slowly.
    • Turn the handle counterclockwise.
    • Turn a lever handle back in line with the pipe.
    • Turn a wheel handle until the wheel stops.
    <1m
  2. Look at the flow from the open tap.
    • The flow is noisy for a short time while air leaves the pipe.
    <1m
  3. Close the tap.
    <1m
  4. Dry the body of the valve with the cloth.
    <1m
  5. Look at the valve again after ten minutes.
    • A dry valve is correct.
    • Speak to a plumber about a valve that is wet again.
    1m

Label the Valve and Tell the Household

Estimated 7 min

Interval between one test of the valve and the next
Unverified — do not rely on this value
CONSULT THE VALVE MANUFACTURER DOCUMENTATION FOR THE EXERCISE INTERVAL

No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.

  1. Attach the label to the pipe near the main shutoff valve.
    • Write MAIN WATER SHUTOFF on the label with the permanent marker.
    • Add the direction to close the valve to the label.
    2m
  2. Put any tool that the valve needs in a place near the valve.
    1m
  3. Show the valve to each adult in the house.
    • Show the direction to close the valve to each adult.
    3m
  4. Record the date of this test.
    <1m
  5. Do this test again at regular intervals.
    • The documentation for your valve gives the interval.
    <1m

Terminology

This page uses one term for each item and holds it throughout, as ASD-STE100 requires. Equipment sellers and other guides use the names below for the same parts.

main shutoff valve
Also called: main water shut off valve, main water shut-off, main water valve, house shut off valve, whole house shut off valve, stopcock, stop tap, main stop valve, water cutoff
gate valve
Also called: round handle valve, wheel valve, multi turn valve, screw down valve
ball valve
Also called: lever valve, quarter turn valve, lever handle valve
curb stop
Also called: street valve, curb box, buffalo box, kerb stop, valve in the box by the road, meter valve
water meter
Also called: city water meter, utility meter, house water meter
stem packing
Also called: packing nut, gland nut, valve leaking at the handle

When to use a professional

Stop if the handle of the main shutoff valve does not move with light hand pressure. Speak to a plumber about that valve. Force on an old valve is how a small job becomes a flood.

Speak to a plumber about a valve that does not stop the flow at the tap. Speak to a plumber about a valve that leaks at the stem after the test. A valve that leaks or does not close fully cannot protect the house in an emergency.

Do not operate the valve in the box at the kerb before you speak to your water utility. The water utilities do not agree about this valve. Only the crews of Seattle Public Utilities can operate an older meter. DC Water gives its customers steps to open the box and to close the valve. Ask your water utility for the rule in your area.

Do not close a valve between the well pump and the pressure tank. The pump can operate against a closed valve and become too hot. Speak to a well contractor about the valves of a well system.

Speak to your water utility if the house has no main shutoff valve. Speak to a plumber about the installation of a valve.

This page does not give steps to repair or to replace a valve.

Common questions

Where is my main water shut off valve?

Look first at the point where the water supply pipe enters the house, because the main valve is almost always the first valve on that pipe. In practice that means a basement, a crawl space, a garage or a utility room, and in warm climates it can be on an outside wall instead. DC Water tells its customers to look where the supply enters the house, usually the basement, or in a concrete box near the street. FEMA's preparedness handouts add that the cutoff is often on the outside wall of the house where the water meter is, and that on a well it is usually at the well pump. If none of those turn one up, follow the cold pipe that feeds your water heater backwards.

How do I turn off the water to my whole house?

Turn the handle clockwise. A lever handle is a ball valve and needs only a quarter turn, ending across the pipe rather than along it; a round wheel is a gate valve and needs many turns until it stops. Then open a cold tap on the lowest floor: the water already sitting in the pipes runs out first, and the flow should fall to a drip and stop. If it never stops, the valve is not sealing, and that is worth knowing now rather than during an emergency.

My main water shut off valve won't turn. What should I do?

Stop. Do not reach for a wrench or a length of pipe on the handle. An old gate valve that has sat in one position for years can shear at the stem or split at the bonnet, and you will have turned a job you were preparing for into the flood you were preparing against — with the only valve that could stop it now broken. This is the professional boundary on this page: a valve that will not turn is a plumber's call. It is a known enough situation that Seattle Public Utilities lists a home valve that is "broken, damaged or gets stuck" as one of the reasons a customer might have to shut the water off at the meter instead — which is the argument for finding out on a dry Saturday rather than at two in the morning.

How often should I test the main shut off valve?

There is no single answer that covers every valve, so this page does not print one. What we can point at is what a valve maker says about its own products: NIBCO's installation, operation and maintenance instructions for its bronze ball valves state that valves must be exercised from fully opened to fully closed periodically to assure continued function, and recommend a routine, periodic exercise program "such as cycling at least once every 6 months". That is NIBCO's figure for NIBCO valves, not a universal rule, and the honest instruction is to check the documentation for the valve you actually have. Pairing the check with something you already do twice a year — the same weekend as the smoke alarm test, say — is how it survives contact with real life.

What about the valve in the box out by the street?

That one is the curb stop, and whether it is yours to operate depends on your utility — they do not agree, so this page does not pretend there is one answer. Seattle Public Utilities states that older meters require a special tool to shut off, that only its own crews can operate those types, and that customers should generally shut off their water with their home valves. DC Water goes the other way for its own customers: it tells them to lift the cover with a large screwdriver and then use a pipe or crescent wrench to turn off the water. Ask your own utility which of those describes you, before you open a meter box. If your house has no shut-off valve at all, Seattle Public Utilities' own advice is to have a plumber install one.

The valve closed but the tap still drips. Is the valve broken?

Not necessarily. A drip that fades away over a minute or two is just the water draining out of the pipework above the tap, and it is normal — especially if you opened a tap upstairs rather than on the lowest floor. A steady flow that does not fade is different: that is water still getting past the valve, and it means the valve is not sealing. Give it a couple of minutes before you judge, and open the tap on the lowest floor in the house so gravity has already emptied everything above it.

Why does this page tell me to open the valve fully afterwards?

Because a valve left part-way open quietly costs you flow at every tap and shower in the house, and it is easy to leave one like that after a check. NIBCO's instructions put its own ball valves on an exercise programme from fully opened to fully closed, and say separately that ball valves are "generally not recommended for modulating service where critical flow rates are required" — a main valve parked half-shut is exactly that. Turn the lever back in line with the pipe, or wind the wheel back until it stops, then run the tap for a few seconds to confirm the flow came back. Turn it back on slowly, though, rather than yanking it open: bringing the pressure up fast against a drained system is how you find out where the weakest joint in the house was.

Sources

Every specification on this page is traced to one of these sources. Tier 1 is a manufacturer document, a published standard, or a government safety authority. See Standards for the full tiering rule.

  1. Tier 1Community Preparedness: Simple Activities for Everyone — Handout Masters (IS-909)Federal Emergency Management Agency, Emergency Management Institute · accessed 2026-08-12 · re-verification due 2027-02-08
  2. Tier 1Installation, Operation & Maintenance Instructions — Installation and Maintenance Guidelines for Bronze Ball Valves, Soldered, Threaded, Press End Connections (585HP series)NIBCO INC. · accessed 2026-08-12 · re-verification due 2027-02-08
  3. Tier 1How to Shut Off Your WaterSeattle Public Utilities (City of Seattle) · accessed 2026-08-12 · re-verification due 2027-02-08
  4. Tier 1Preparation Helps Keep You and Your Family SafeDC Water (District of Columbia Water and Sewer Authority) · accessed 2026-08-12 · re-verification due 2027-02-08
  5. Tier 1TM 3-34.70 / MCRP 3-17.7E, Plumbing, Pipe Fitting, and SewerageHeadquarters, Department of the Army (Army Publishing Directorate) · accessed 2026-07-29 · re-verification due 2027-01-25

Revision history

Current version 2 · updated 2026-08-12 · next review due 2027-08-12

  1. v2 · 2026-08-12Independent source audit. Every quotation on the page and in the five registry entries was re-fetched and checked against the source's own words this session: FEMA IS-909 (training.fema.gov, HTTP 200, 'Locate and label main water cutoff. Make sure any special tools needed are stored nearby.' and the well-pump and outside-wall tip, page footers 'September 2011'), NIBCO 585HP IOM (HTTP 200, section VII.1 'Valves must be exercised from fully opened to fully closed periodically to assure continued function. NIBCO recommends valves be put on a routine, periodic exercise program, such as cycling at least once every 6 months.', Review Date 4/23/2020), Seattle Public Utilities (HTTP 200, 'Older meters require a special tool to shut off, and only SPU crews can operate these types.'), DC Water (HTTP 200, 'Look for the main valve where the water supply enters your house (usually in the basement) or in a concrete box near the street.'), US Army TM 3-34.70 (HTTP 200, 16,362,037 bytes, paragraph 7-2 'Gate valves come in three models: (1) rising stem outside screw and yoke, (2) rising stem inside the screw, and (3) nonrising stem inside screw.' and chapter 11 'Gate valve. This valve is hand-operated by turning a wheel'). All quotations were verbatim and correctly attributed; no number was overstated and no threshold was flattened into a measurement. Both specifications still carry no digit and still route the reader to the manufacturer. Four defects were corrected. (1) A missing hazard: the page told the reader to reopen the main valve on a system that had just been drained at a tap, with no instruction on rate. Western Municipal Water District publishes 'Warning: Turn the valve slowly to turn on the water in your home. Opening the valve too quickly can damage the pipes.' A NOTICE now sits before s16 and a substep says to turn the handle slowly. The level is NOTICE, not WARNING, because the consequence is property damage: that is the ANSI Z535.4 severity and it matches the other property-damage notices on this page. (2) Rule 2: the professional boundary and the FAQ flatly forbade operating the curb-stop valve, which contradicts DC Water — a cited tier-1 source that gives its own customers steps to lift the cover and close it. The disagreement between Seattle Public Utilities and DC Water is now published and both are named, and the reader is routed to their own utility. (3) An unsourced prevalence claim, 'a stiff valve is one of the most common findings when people do this check for the first time', was replaced with what Seattle Public Utilities actually says: a home valve that is 'broken, damaged or gets stuck' is one of its listed reasons for needing the meter instead. (4) The FAQ attributed 'operate them fully open to fully closed rather than parking them in between' to NIBCO's maintenance clause, which is about the exercise stroke and not the resting position; it now cites the clause that does carry the point, NIBCO section VI, 'generally not recommended for modulating service where critical flow rates are required'. NIBCO's throttling CAUTION is conditioned on 'less than 45 degrees open' and that threshold is deliberately not carried onto the page as a number. A well-system boundary was added: do not close a valve between the well pump and the pressure tank, because the pump can then operate against a closed valve. The page's applicability includes well supplies and carried no such limit. Staged for admission in data/sources-additions-find-and-test-the-main-water-shutoff.json, both read in full this session: Western Municipal Water District 'How to Turn Off Your Water' (the slow-opening warning, the air-clearing step and the quarter-turn ball valve operation) and City of Hamilton, Ohio 'Locating & Operating Water Shut-Off Valves' (wheel handle equals gate valve and 'may take two or more full revolutions'; lever handle equals ball valve, closed perpendicular to the pipe, 'should stop at a 1/4 turn'). These back the ball-valve and gate-valve handle claims in s6, s7, s9 and s16, which version 1 carried with no citation. They are not yet in rec.sources because they are not yet admitted to data/sources.json; add them there when sources_admit.py runs. Hamilton's 'two or more full revolutions' is a floor and is correctly not published as a turn count: the page says 'many times' and tells the reader to count the turns on their own valve.
  2. v1 · 2026-08-12First draft. Valve location, labelling and the reminder to store any special tool nearby from FEMA EMI IS-909 'Community Preparedness: Simple Activities for Everyone' handout masters (utility outages handout, September 2011), read this session. Valve exercise and the fully-open/fully-closed instruction from NIBCO INC. Installation, Operation & Maintenance Instructions for bronze ball valves (585HP series, review date 4/23/2020), read this session. The home-valve-before-meter-valve boundary and the special-tool limit on older meters from Seattle Public Utilities 'How to Shut Off Your Water', read this session. Location and marking guidance from DC Water 'Preparation Helps Keep You and Your Family Safe', read this session. Gate valve construction from US Army TM 3-34.70 (already registered), read this session. No safety-critical value publishes as verified: both specifications route the reader to their own valve or to the valve manufacturer documentation. NIBCO's six-month exercise figure appears only in the FAQ, named as NIBCO's figure for NIBCO valves, because it is manufacturer guidance for one product family and not a universal interval. Written independently in Simplified Technical English; no source sentence was paraphrased into a step.

Corrections to this page are listed in the public corrections log. Reports that are credible and not yet verified are listed in the public errata register, and an open one renders above the step it concerns.

Comments and corrections

Found an error? A correction with a manufacturer source is applied and logged publicly. You can also write to corrections@fixchecklist.com.

Every step above carries its own report control, which tags the report with that step so a correction reaches the right place. For anything about the procedure as a whole — the order of the sections, a step that is missing, something that did not match your equipment — use this: report something about this whole procedure.

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