Why don't pipes in outdoor water meters freeze?

[Stephen Tashiro]

In my town, many water meters are at the bottom of holes in the curb. The holes have a plastic cover. The water pipe around the shutoff valve is exposed. Why is there no concern about the pipe freezing?

The waterlines through the yards must be buried to avoid freezing, although in this part of the country (southern NM) they don't have to buried very deep.

[Andrew Seemann]

Apparently it doesn't get cold enough long enough for them to freeze. The ground has a lot of thermal inertia as well, so that may be enough to keep them from freezing.

Around here, water meters are always inside buildings. Frost depth can go from anywhere from 12 inches to about 60 inches under normal ground. Under roadways it can be even more. City waterlines tend to be buried at least 7 feet below ground, and they still can occasionally freeze under roadways if we get a really long cold spell. The worst is when we have sub-zero F temps for extended times with little or no snow cover. Snow is a really good insulator. About 10 years ago we had an early snow and the ground was covered with deep snow from November to March. Even in the cold of January and February, the grass was still green under the snow and the ground hadn't frozen.

[Stephen Tashiro]

Around here, water meters are always inside buildings. Frost depth can go from anywhere from 12 inches to about 60 inches under normal ground. Under roadways it can be even more. City waterlines tend to be buried at least 7 feet below ground, and they still can occasionally freeze under roadways if we get a really long cold spell..

I'm glad I live in New Mexico!

I wonder if city waterlines were buried 7 ft deep throughout the history of Minnesota city water. I can see digging a 7 ft trenches with modern excavating equipment, but with only manual labor it's hard to imagine.

[Stan Calow]

The water in the city water mains is cold but warm enough to keep the pipes from freezing. Soil temperatures below the frostline are stable enough to keep it from freezing. The connection between the city main and the service line at the meter pit and the valves there are pretty robust, so that the weak point for a breakage will be somewhere else. Like where a service line was nicked during installation.

[Andrew Seemann]

I'm glad I live in New Mexico!

I wonder if city waterlines were buried 7 ft deep throughout the history of Minnesota city water. I can see digging a 7 ft trenches with modern excavating equipment, but with only manual labor it's hard to imagine.

Well, the frost depth hasn't changed, so yes, they have always been buried that deep. And if they weren't, they got replaced that deep

Note that the water in the mains is warm enough to keep the pipe from freezing, even if the ground around it is frozen, if it is moving fast enough. If it is stationary or moving too slow long enough, it will freeze. Usually a stream about the size of a pencil will keep it from freezing for a line around 3/4 to an inch. Larger lines will need more movement. I had a relative whose line froze a few years back. The city determined it was their fault because the line under the road wasn't deep enough, so they covered the cost of thawing it (which can be hundreds of dollars or more), and told him to leave a faucet running and they would deduct that cost from his water bill.

When you do have a freeze burst, it usually isn't where the pipe froze, but between two blockages, like a closed valve and a freeze, or two freeze points. The water in between tries to freeze, but it can't expand to form ice crystals, so the pressure builds and builds until the pipe fails, typically at a seam or weak location.

I think I one of the reasons PEX is preferred underground it that it can expand slightly and accommodate that pressure from freezing better, although it can still burst if the pressure gets high enough.

[Edward Dyas]

Meters can and do freeze up. The water utility usually knows what depth provides enough insulation to prevent it. On a cold day when you take that plastic cover off the air should be a great deal warmer. They kind of have to push limits by putting the meter closer to the surface. At least if a pipe broke and leaked there you would have water coming out of the ground there. 20' from the meter if a pipe froze and broke it could leak for years and you may not know it so it may be buried deeper.

There is also the issue that most people have no idea where their water supply lines are. Burying the pipe deeper keeps them from cutting the pipe when they are planting a bush.

[roger wiegand]

Short answer is that they can and do freeze, which is why they are installed under the frost line. We have shutoff valves at the street that are accessed using a ~6 ft long wrench, meters are inside houses.

[W Craig Wilson]

We had the same situation in Victorville CA. Of the six years I lived there, only one winter was below freezing long enough (8-10 days) to cause problems. But when meters and valves started to freeze, there was a tremendous mess of gushers and ice flows all over the neighborhood.

Many houses had water heater and washing machines in the garage. That same winter, when the water line to our washer split open, there were no 1/2 in copper pipe fittings left in any home centers or supply houses. I ended up using a cludge of brass pieces to repair the pipe.

[Mark Bolton]

I can see digging a 7 ft trenches with modern excavating equipment, but with only manual labor it's hard to imagine.

Generally in cold climates there would never a meter at the street unless the meter well could be located below the frost line (usually 2' or less). There would only be a service shutoff at the street (long pipe with a cap at grade/pavement that allowed shutting the main to the residence/building with a long T handle wrench) but the meters were all inside in the warm. 30+ years ago most utilities began swapping out internal meters for remote reading meters that had a sender on the exterior of the home so the meter reader could read it from outside and didnt need access or have to rely on the homeowner to read their own meter.

In days of old labor was cheap. Deep ditches just took longer to dig. ;-)