Shutting off residential water supply. You Need To Know This:

Shutting Off The Water Supply

In This Article:

Tips on shutting off the water supply, and why it's sometimes a good idea to shut off the water when away from home for more than a few days.

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By , Editor

Simple But Important:

There are several reasons why every homeowner should know how to shut off the water supply:

  1. Emergencies: If a major leak happens suddenly, you need to know how to shut off the water to prevent serious water damage.

  2. When winterizing the plumbing system.

  3. Precautions: It's a good idea to shut off the water supply if the house is going to be unoccupied for any length of time, even a period as short as a weekend. In any area with cold winters there is a risk of plumbing pipes freezing during cold weather. I once had a pipe fitting break while away, and having the water shut off prevented a potentially disastrous flood. Read more about this later...

  4. Working On The Plumbing: If you're going to repair or modify the plumbing supply system, then you need to know how to shut off the system.


Every house with running water has either a private well or some sort of externally-supplied water service, such as a municipal water system.

Shutting Off The Municipal Water Service:

If a house is on the "city" water system there will be a pipe entering the building somewhere. If the house has a basement or crawl space, I would expect to find a pipe that passes through the foundation, or possibly the floor. I would also expect to find a water meter nearby.

This recently-built house has two ball valves. Each of these valves will shut off the water to the entire house. Why two valves? The valve above the water meter (i.e. downstream of the meter) simply eliminates the need to drain the entire system if the meter needed to be removed.

City water pipe entering the basement.


Closing a quarter-turn ball valve. To turn off the water on this house, I simply turned the valve handle a quarter-turn. When the handle is perpendicular to the pipe, the valve is closed. When the handle is parallel to the pipe, it's open.

Note that I closed the upstream valve (the valve closest to the point where the pipe enters the building). If I only closed the other valve, the meter or the fittings next to it could still leak.


In my own house (built in 1963) there are older valves with  round handles. To turn off the water, I turned the handle clockwise until it stopped.

These valves are often very difficult to turn when they haven't been used for a while. Sometimes I have to use large pliers to unstick the handle, and then it will turn without a fight.

Shutting off a globe valve on an older house.


Note: Old valves can be deceiving. I have worked with older valves where the handle turned freely (for up to a full turn) and then encountered some resistance, giving the feel that the valve was shut off. But... that freely-turning action was simply the "backlash" (or slop) in the screw threads of the internal mechanism. If the handle turns suspiciously easy, I will try opening the valve instead (by turning the handle counter-clockwise) and then closing it again. Sometimes the internal parts become stuck from years of mineral deposit buildup, and it takes some careful force to break up this crud. It may take several opening/closing attempts to loosen the internal parts. Once a hard-water-clogged mechanism starts to move, it offers much less resistance.

If A Small Leak Develops: After closing and opening one of these older shutoff valves, they often develop a small leak around the handle. The water is leaking around the packing, which is a flexible seal around the handle stem. Usually this leak can be stopped by tightening the packing nut, which is the hex nut where the handle stem meets the valve body. But... sometimes tightening the packing nut doesn't fix the leak, possibly because the handle stem has some crud on it, or the stem has been gouged by using pliers directly on the stem. The stem and packing can usually be replaced... but that may require having the utility shut off the water at the street, which isn't cheap. These old valves are inferior... that's why everyone uses ball valves today.

Since old valves can be troublesome, it's probably best to shut off the downstream valve if there is a valve before and after the water meter. That way the upstream valve can be closed so the other valve can be repaired, if necessary.


Shutting Off A Private Well System:

Typical residential well system with pressure tank. If a house has a well, there will probably be a pressure tank near the point where the water line enters the house. In my area, the pressure tank is usually located in the basement or crawl space, but I've seen houses with shallow crawl spaces where the tank was located on the main floor.


The most important thing to do is simply turn off the power to the pump by turning off the circuit breaker.

Most well pumps have 240 volt motors, so the power will be controlled by a 2-pole breaker, which is twice as wide as ordinary breakers.

Sometimes there will be a separate disconnect box near the pressure tank. This is a small metal box with a handle and markings that say ON and OFF. This switch can be turned off instead of the breaker, if desired.

Turning off the circuit breaker for the well pump.

I have also seen an older house where two separate fuses were used to control the power to the well pump. Of course, that particular house was a textbook of code violations.


Main shutoff valve on a well system. On this system (in my previous house) I installed a ball valve just downstream from the pressure tank. The water enters the tank through that silver-colored pipe at the bottom-right of the photo, the vertical copper pipe leads to the rest of the house.

Instead of turning off the breaker, sometimes I would just shut off this ball valve. However, if a leak developed between this point and the pipe entering the basement from the well, I would still have a flooding problem.

If a well system is shut off by turning off the power to the pump, the entire contents of the pressure tank could spill into the house if a leak occurred. This tank held 36 gallons.

If the system is shut off by closing the main valve, and leak develops in the main system, then only the volume of water inside the pipes will spill out. That could be a couple of gallons.

Perhaps the best approach is to shut off both the power and the main valve.

Yet Another Story:

I once had a near-disaster in the house shown above. Just downstream of that red handle there was a whole-house "swirl-down" water filter. The filter had a clear plastic bowl so you could see the junk that it was keeping out of the system. At the bottom of the bowl there was a male pipe thread. When I bought this filter, the plumbing supply shop sold me a PVC ball valve with female threads to attach to the bottom of the bowl. Every month or two I would just open the ball valve and all the debris in the filter bowl would blow out into a bucket. It worked great... we had a lot of crud that was being picked up by the well pump and this filter kept it from clogging all the faucet aerators.

My then-girlfriend had taken a job downstate and only came up north on weekends. The first winter she didn't feel like driving up every weekend, so I would drive the two hours south to Grand Rapids. I got into the habit of shutting off that ball valve before leaving, because I knew the old house had a history of freezing pipes.

One Sunday night in February I came home and went downstairs to turn on the water. Before I reached the shutoff valve I noticed a 3-foot-diameter puddle of water on the floor. Puzzled, I looked around for the leak. I could see drops of water on that PVC ball valve, and where the valve was screwed onto the clear plastic bowl there was a good-sized crack. If I hadn't shut the water off, I would've come home to a flooded basement. It's hard to say exactly how much water would have leaked out... it might have just dampened the concrete floor or it might have flooded a foot deep. The point is... I'm really glad I got into the habit of shutting off the water whenever I go away.

Shutting off the water every time you spend a weekend away from home may sound paranoid to some people, but I've seen enough burst pipes and water damage to make me realize how serious a problem this can be. I've read that water damage is the second-biggest source of homeowner's insurance claims. Your insurance may cover water damage from a burst pipe, but it might not be able to replace all of your belongings. This kind of mini-disaster is simply a major hassle. And there is still the deductible.

One of the most common sources of gushing water leaks, besides freezing pipes, are the washing machine supply hoses. Most hoses are just rubber, and these have been known to fail without warning. It's a good idea to periodically inspect your washing machine hoses and replace them if the rubber appears swollen or cracked. For a few extra dollars you can buy washing machine hoses that have a braided stainless steel covering. I understand these premium hoses are much more burst-resistant.


All House Are Not Created Equal:

There are some types of houses that face little or no risk of damage from major plumbing leaks:

  • Single-story houses built on a concrete slab, with all of the plumbing installed below the floor. This type of construction is common in the southern and western states.

  • Single-story houses built on a crawl space or basement, with nothing valuable stored in the crawl space or basement.

Some types of houses face significant risk of water damage from plumbing leaks:

  • Any multiple-story house with plumbing on the upper floors. My old saying applies: "Pipes behind plaster, recipe for disaster".

  • Any house with water supply pipes in the ceiling. I understand this practice is sometimes done in the southern and western states.

  • Houses with basements, where the basement is finished or valuable items are stored there. A basement is basically an empty swimming pool beneath your house, so there is always a chance that "pool" will fill up.

For homeowners in this last group, it's worth taking a minute to shut off the water when leaving for a few days, unless you have somebody checking on your house every day.

Some people install a sump pump in their basement to pump out water that may enter through a leaky foundation. A sump pump will also pump out water if a pipe breaks. It won't keep everything dry, but it should prevent the water from getting too deep. However, I have heard of people who had a pipe burst, and they had a sump pump, yet the pump burned out from constant use. They still ended up with a flooded basement. That sounds like a good reason to use a heavy-duty sump pump that is rated for continuous use.

More Info:

Tools That May Be Required:

  • Channel-Lock Pliers
  • Adjustable Wrench

Materials Used:

  • None
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Written February 22, 2008