The UK has just had a cold snap. I don’t actually think it got much colder than -5C in Southern England but a lot of pipes, including mine, froze over. In Eastern Europe they regularly have temps of -25 or colder, yet the water keeps flowing, how is that done?
For outdoor piping, you need to bury it sufficiently far below grade such that it never freezes. This varies based on local climate, but may be several feet below grade.
For indoor piping in cold climates, you avoid routing pipes inside exterior walls. Sometimes kitchen or bathroom cabinets that are against exterior walls can get cold enough to freeze under-sink piping; if this is a known problem, then you keep those cabinet doors open during cold snaps.
For houses that are unoccupied/unheated for long stretches (e.g. vacation homes in northern locales), it’s common practice to drain water supply pipes and pour antifreeze into sinks and toilets (to keep the drain traps from freezing).
To add to Machine Elf, you can also use Heat Trace Cable.
At my father-in-law’s cottage, they had water fed from a spring. The inlet pipe from the spring box to the cistern had heat trace cable along the length of it to keep the pipe from freezing since it ran on/close to the surface.
We’ve had trouble with frozen pipes in the past, but they’re PEX, so they haven’t burst. Except…
A couple of years ago we expanded the deck a bit. The copper pipe for the faucet out back needed to be extended to above the level of the deck. (Before, it was nearly at ground level – which made it difficult to use.) That was Summer. Winter came and there was a hard freeze. Fortunately, this was just after we returned from vacation. The extended pipe burst at its lower fitting. When it was repaired, we had the guy add aluminum-backed fiberglass insulation… and
heat tape. Since the temperature almost never goes below 20°F (-7°C) the insulation is probably good enough. But we plug the heat tape in when it gets cold anyway.
And we also had the PEX pipes under the house insulated.
I live somewhere where -25C doesn’t even qualify as a cold snap. Machine Elf has pretty much covered it. Water lines outside here are buried to at least 2m (usually more like 2.5m). Best practices inside have no plumbing at all in exterior walls, and most houses have basements that are heated sufficiently to avoid lines under the floor from freezing. My house has no risk of freezing lines even at -40, barring failure of the heating system of course.
I would add to Gorsnak’s post : really good insulation in the walls, and if you need a water feed close to a wall, it’s not actually in the wall.
For instance, people often like a kitchen sink to face a window, to be able to look out while washing up. That’s the arrangement in the Piper kitchen. But the water pipes aren’t built into the wall. They come straight up from the basement under the sink, with a few inches clearance from the wall. That means they are at room temp, not affected by the temperature in the wall. Of course, I live a bit south of Gorsnak, so extreme temps mean -38, not -40. 
I remember I was really taken aback when I was in England and Ireland and realised that the pipes on the outside wall of houses were actually water and waste pipes, not just eaves-trough drains. :eek:
Oh, and in response to Johnny L.A.: We don’t use our outdoor taps in the winter (which usually runs from mid-November to early April).
One of our annual chores is disconnecting the hoses, usually in late October, turning off the water to the outside taps from the indoors shut-off, and then opening the outdoor taps so if there’s any water in the pipe or tap, it will drain out, or if there’s a sudden cold snap, the ice can expand out the tap without breaking the pipe or tap. Then in spring, reverse the process.
Oh, and taking in my outdoor sump pump of course - usually late October or early November.
Of the five posters replying to the OP, three are Canucks. We think about these things.
An alternative is installing frost-proof spigots. These locate the actual valve far inside the house, and the knob you turn outside the house has a long stem to reach the valve. The length of pipe downstream of the valve can thus drain freely when the valve is shut off. No indoor shut-off to deal with on a seasonal basis (though you’ll still want to disconnect any hoses you may have attached to those spigots).
In-ground lawn irrigation systems are a bit more work. The network of pipes that feeds the sprinkler heads is typically buried only 6-12 inches below grade, and of course the sprinkler heads themselves are at turf level. Moreover, these systems always include a loop of pipe that extends up into open air and includes an anti-siphon valve. All of this stuff is susceptible to freezing in the winter. Standard practice involves shutting off that branch of piping from inside the house, connecting a compressed-air line to that branch (typically there’s a fitting on the AS valve), and blowing all of the water out through the sprinkler heads. Lawn care companies will stop by and do this with a trailer-mounted air compressor for $50 or so.
If this is only an occasional problem … like a few days a year … we can trickle water through the value … replacing the water in the pipe with warmer water all the time … costs a bit for extra water, but that cost is tiny compared to just one broken pipe …
OP: this is probably the key difference of why so many English houses froze: is this true of your house–does it have any pipes exposed on the outside of the house?
Only the eavestrough drainage pipes. Nothing related to the indoor water system.
I think the bolded is the key. Of all the pipes I know of that have frozen, they were either in houses on slabs rather than basements OR were under additions that don’t have any part of the basement under them (so the additions have crawl spaces).
We don’t go to any particular effort to heat our basement but even when it’s -20F outside the basement stays in the mid-50s at coldest.
You would too, if you lived in a area where, technically, you would have to warm the freezers during the cold spells to keep them at the nominal temperature. 
Actually, despite being located farther south, Regina’s climate is a bit colder than Saskatoon’s. The average mean and average low in the winter months is about one degree lower in Regina. I wonder if they bury the pipes lower to compensate.
For low snow ears, cover the septic field with straw.
It got down to about -12C here at its coldest last week, and a few winters ago it got down to -15C. That’s about as cold as you can generally expect in southern England (which actually is often the coldest part of the UK in winter cold snaps, strangely). I didn’t see any problems from pipes freezing around here, other than quite a few people had the condensate pipe from their boiler freeze up, as they are usually just routed externally.
I think a few water mains froze and burst in some parts of the country, as they are not buried very deep underground in the UK.
And Moose Jaw’s temps are a bit warmer than Regina as well…
It was cold and snowy this morning. A car with Saskatchewan plates passed me. Coincidence? I think not.
I think the folk in the Highlands would disagree with you. As recently as 1982 it was -27C in Braemar, just a bit inland from here. Two years later it was a balmy -23 in Grantown-On-Spey.
Southern England doesn’t even feature in the top ten.