Reuben Saltzman

Shut-off valve basics

As a home inspector, I tend to take shut-off valves for granted and assume everyone knows what they are, how they work, and what can go wrong with them.  I recently had a client share a story with me regarding some problems he ran in to with the shut-off valves at his house – we’ll call him Sir Walter Raleigh.  Walter thought that some of the problems he ran in to while replacing his water heater were things that most homeowners don’t think about or know about, and would make for good blog fodder.  I agreed.

Gate Valves

Walter’s woes began when he tried to shut off the water to his water heater.  All water heaters are supposed to have a shut-off valve on the cold water supply.  If the water heater is going to be replaced, this is where the water gets shut off.

Some homes also have a valve on the hot water side of the water heater – these aren’t required, but they’re also not a problem.  They just make it a little easier to service the water heater.  I’ve heard some home inspectors call shut-off valves on the hot side of a water heater a safety hazard, but they’re not.  They’re fine.

As you may have guessed, Walter couldn’t shut the water off completely.  He had an old gate valve at the water heater, and the gate valve was fouled – it shut off most of the water, but most isn’t good enough.  A gate valve has a round handle on it, and shuts off the flow of water by essentially closing a gate.  The three photos below show a gate valve in the open position, halfway open position, and fully closed position.

Gate valve fully open Gate valve halfway open Gate valve fully closed

As you can see, the handle never goes up and down as the gate opens and lowers; for this reason, it’s impossible to know if a gate valve is in the open or closed position just by looking at it.  The exploded view below shows what the guts of a gate valve look like.

Gate valve exploded

When the gate valve at the water heater wouldn’t completely shut off the flow of water, Walter decided he better replace the valve.  He tried to shut the water off  at the main shut-off valve for his house, located downstream from the water meter.   That valve was fouled too.  Next, he went to the other main valve for his house – the one upstream from the water meter.  Can you guess where this is going?  That valve was also fouled.  Three fouled gate valves, no way to completely shut off the water to his house.  It’s a good thing this was only a ‘project’ and not an emergency.

Do you know where the main shut-off valve to the water supply in your home is?  If not, take a quick peek at your home inspection report – home inspectors are supposed to report on the location of the main water and main fuel shut-off valves.  For most buildings in Minnesota, the main shut-off valve is located in the basement near the front of the building.  If there is no basement, the valve will probably be located in the furnace room.

Main shutoff valves

Curb Stop

To continue with his project, Walter had to replace his main shut-off valves.  To do this, he needed to call the city water department and have them turn off the water to his house at the street.  The first shut-off valve to a home’s water supply is located below the ground near the street – this is call the curb stop, or the curb cock.  Sometimes the valve is buried in the dirt, and sometimes they’ve completely covered in concrete.  The photo below shows an example of an access cover located in the front yard.

Curb cock access in yard

Here’s a closer view.

Curb cock access in yard close-up

In Walter’s case, it took the people from the municipal water supply about 40 minutes to even find the one in his front yard, because it was buried.   At least it wasn’t buried below a sidewalk.  Here’s what the access cover may look like if it’s located at a driveway or sidewalk.  It’s tough to mistake this for anything else.

Curb cock access in driveway

When the city turns the water on or off from the curb, they use a special tool like the one pictured below.


Ball valves

Once the city had turned off the water supply to his house, Walter started replacing his valves.  He hired a plumber to replace the first valve before the meter, and then did the rest of the valves himself.  Instead of using gate valves, he used ball valves.  Ball valves are much easier to operate –  they have a lever handle that only needs to be moved 90 degrees to be turned off completely.  By comparison, the gate valve that I showed above took me 15 turns of the wrist to completely shut off.

When the handle of a ball valve is parallel to the valve or pipe, it’s open.  When it’s perpendicular, it’s closed.  This makes it easy know if a ball valve is open or closed, just by looking at it.  The ball valve below is in the open position.

Ball valve

The photos below show a ball valve in the open position, halfway open position, and fully closed position.

Ball valve fully open Ball valve halfway open Ball valve fully closed

Ball valve are also much less likely to leak; I can’t recall ever finding a leaking ball valve, but I find other types of valves leaking all the time.

Stop Valves

Walter didn’t have any stop valves to deal with, but as long as I’m talking about different types of valves, I should mention stop valves as well.  Stop valves are commonly found at plumbing fixtures – for instance, at the water supply line to your toilet.  A stop valve looks very similar to a gate valve, but it’s a little bit more compact.  A stop valve works by moving a stopper up and down.  The photos below show a stop valve in the open position, halfway open position, and fully closed position.

Stop valve fully open Stop valve halway open Stop valve fully closed

Check out the stem in these photos – you’ll notice that when the valve is fully closed, the stem isn’t visible at all.  Most stop valves are much smaller than the one pictured above, but I decided to use a larger one for my example because it gives the best view.  The photo below shows an exploded view of the guts of a stop valve.

Stop valve exploded

Like gate valves, stop valves take more time to operate and they’re more prone to leaking.  If you have a leaking stop valve, you can often stop the leak by using a wrench to tighten the nut right below the handle.  Lefty loosy, righty tighty.


If you want to be proactive about preventing a plumbing headache, check out the main shut-off valves at your home.  Are they accessible?  When the valve is fully closed, does this completely shut off the water to your house?  Is the curb stop in your front yard visible?  It’s nice to know about this stuff before you have a problem.

Gate valves, stop valves, and ball valves are the most common types of valves to find in your home.  If you have any projects that require replacing valves, I recommend using ball valves, also known as quarter-turn valves.  They’re easier to use and less prone to leaking.

Reuben Saltzman, Structure Tech Home Inspections


11 responses to “Shut-off valve basics”

  1. bill
    November 14, 2012, 9:20 am

    Are two valves required at the water meter or is it just a nice thing to do.

    May not be code but I attached a ball valve following my fouled main gate valve using a compression fitting. Since I live in a townhome and getting them to shut off the entire water supply to the building would have been a major event, I just opend up the ball valve with the outlet of the valve directed to a bucket and did a quick job of cutting the copper and attaching the valve so I could close it and get on with the rest of the work.

  2. Tom
    May 13, 2013, 5:52 pm

    Very old houses may not have inside cutoff valves or cutoff valves sticking out of the foundation, If you have a problem, these old houses should have been supplied with a water key and you can cut off the water street-side upstream from the meter, The gate valve upstream from the meter should turn off the water if turned counter clockwise one quarter turn more or less. These are usually functional but can require a lot of strength to turn them but you really need a water key to turn them off.

  3. Cam
    May 15, 2013, 1:47 am

    I’m getting ready to replace an older water heater which does not currently have a cutoff. Thanks for validating my purchase of the ball valve for that purpose and reminding me about the water key before I start the project. Excellent photos and descriptions of the functions of the valves.

  4. dawn connors
    September 7, 2013, 3:02 pm

    Rueben, please, i DESPERATELY need some help n information. PLEASE?! There is a broken pipe on my block. My basement flooded with chlorinated water for 5 months. Nth neighbors have had water flood their basements for months. Our waterauthority refuses to accept responsibilit. I know it is a broken municipal line because when water company came to listen for a leak on their line three basement s drie. That is until after the water company left n the water started again. The scwa closed the valve at the corner if my block and when they were dine, they opened the valves.again. There are valves at both ends of my street. What do these valves do?why did the flooding stop when then closed the valves n start again? How can i prove that the damage to our homes was because of this broken pipe. (i hired a plumber for $5000. And he told the water company so they closed.yhe valve, again.

    Please,.can you help me? If i undrrstand how the valves work in tandem, i can open both to start flooding again. I just dont know what tge valves do.

  5. Reuben Saltzman
    September 8, 2013, 6:14 am

    Hi Dawn,

    I also don’t understand how the valves you’re describing work.

  6. Dan
    September 19, 2013, 11:49 am

    My ( residential – detached ) home main shut off is ( was ) leaking. I had caused the leak by shutting off the valve. When I opened later it was going drip drip drip…. ( 50 year old house in Ontario Canada )

    After reading the above web content I simple got a wrench and tightened the nut you described. The leak went away and so did the massive headache. I was about to call an emergency plumber and the city.

    Thank you a million times !

  7. Gator Bite 3/4" Hot water valve replacement to hot water tank question - Community Forums
    September 28, 2013, 11:53 am

    […] a water heater btw). I found the statement below under the heading Gates Valves on this link- Shut-off valve basics | Structure Tech Home Inspections – but I have no idea whether or not "They're fine" as the author says or whether many other […]

  8. Allan
    November 8, 2013, 3:37 am

    I recently replaced my washer and dryer and found all my valves were seized up so I had them replaced with ball valves. Was wondering if working the valves say once a month or so would be a good idea.

  9. Reuben Saltzman
    November 8, 2013, 4:55 am

    @Allen – it wouldn’t hurt, but it also probably isn’t necessary.

  10. Kenneth
    November 12, 2013, 11:32 am

    Whenever I take a shower I hear a groaning sound coming from my water heater. Do you what that could be?

  11. Reuben Saltzman
    November 12, 2013, 3:56 pm

    @Kenneth – here’s some info I copied word for word from a water heater manufacturer’s site:

    This is usually caused by the formation of scale and sediment. Minerals will form a scale on the bottom of the inner tank that traps minute amounts of moisture. Heat from the gas burner changes these tiny trapped amounts of moisture to steam and the pressures developed cause the rumbling and pounding noises. In addition to being annoying, accumulation of sediment and mineral deposits in the bottom of the tank can appreciably shorten the tank life of the heater. The sediment can interfere with the transfer of heat from the flame through the tank wall to the water. The sediment acts as an ?insulation?, restricting heat transfer and may contribute to a ?not enough hot water? trouble call. If the tank is not periodically drained and flushed, the sediment will continue to accumulate on the bottom the tank. The result is a clogged drain valve and scale build up – eventually to the point it may cover the immersed thermostat bulb.

    If that’s not what your hearing, I don’t know what it could be.

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