No question about it - use 2 insulated thermal tubes. In SW WI I use (2) 30" insulated heat tubes on top of a 2 ft section of 12" regular drainage tile for 7 ft total to the top of the raised concrete.

Also get the waterlines deep enough and for insurance, wrap a thermostatically controlled heat tape secured with good electrical tape around the vertical waterline coming up, put some foam type pipe insulation around the vertical and heat tape with the thermostat on the waterline just above your shutoff valve, secure the foam insulation with good electrical tape or good cable ties. You only get one chance to install a waterer correctly.

This costs maybe $25 to do at installation but can make a world of difference when it's -30 F in January!

If this is your first waterer, remember do NOT backfill the insulated nor drain tile tubes.  Here is a picture of a recent SW WI installation I did for a pasture waterer, fyi. The 7 ft goes down from the top of the concrete. At installation of the waterer I electrical taped the orange thermostat to the waterline just above the shutoff valve and wrapped up to the thermostat (but not over it) with more pipe insulation.

Do it right the first time!

Good luck

Jim

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IMG_1926_waterer installation prep for Mirafount w insulated tubes andfoot shutoff.jpg (117KB - 314 downloads)