Will a slow sand water filter survive freezing weather?

The filters we work on here in western Washington state have been in operation outdoors through temperatures as low as 15 degrees F (at night) for as long as 1 week, with below freezing (32 degrees F) continuously for 7 days. During these times, the filters did freeze up solid and the water stopped flowing. When they thawed out, they resumed functioning without any major damage, after one modification. At first, the pipes that were glued cracked. After that happening the first year, we started putting the filters together without gluing the pipes. When the filters freeze the pipes just slip apart. There is one exception here. The filters that purify shallow well water did not freeze up as long as they continued to run. This is because the water 10 feet down,here, is way above freezing, and it is warm enough to keep the filters from freezing up, as long as it keeps running. As long as your source water is warm enough to offset the below freezing temps, and your output pipes from the filter don’t freeze up, the filters will keep running, and will purify water at 30 degrees (with somewhat reduced efficiency) . The problem we have here is that the output pipes freeze. That stops the flow and then everything freezes up. Below 15 degrees F – I do not know what would happen. All this said, I must stress that we do not have severely cold winter weather here for extended periods of time (at this specific location) as a general rule; and we have not had the opportunity to test these filters for more that 7 days of continuous below freezing temperatures. If you are in Alaska, the Yukon territory, or north eastern Canada or the northeastern part of the U.S. your winters will most likely be much colder and more severe than here.  Keeping a slow sand water filter running in Siberia, or any mountainous area where there are severe temperatures below freezing will be a real challenge. If the filter can be kept above freezing and water continuously running through the filter it will survive; but that might not be possible. Anyone who has information, or experience,  about running one of these filters in extreme blow freezing temps will hopefully post here.