Winter water: the arithmetic before you buy a heater

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The tank freezes in December. The decision that decides whether that matters gets made in August, while you still have daylight and the ground is soft enough to dig.

This is the arithmetic worth doing before the hardware question — which heater, which tank, electric or energy-free — because none of that means anything until you know how much water has to move and what it costs to keep it liquid.

How much they actually drink

The figure most people carry in their head is a summer figure, and winter demand is roughly half of it. Extension work puts a 1,300-pound cow at around 40°F between nine and fifteen gallons a day. The spread inside that range is not weather. It is production stage: a dry pregnant cow sits near the bottom, a lactating cow near the top.

The rule of thumb underneath it is about a gallon per hundredweight for dry cows and bulls, and roughly two gallons per hundredweight once she is milking.

Run it for your own outfit before you size anything. Forty dry cows at 1,300 pounds is somewhere near 400 to 500 gallons a day. A hundred-gallon tank is not a day of water. It is about four hours of it, which means the number that matters is not the tank's capacity but how fast it refills.

The part that catches people

In genuinely hard weather — deep cold with wind on it — cattle drink less, not more. Then when it breaks they drink hard to make it up. The same thing happens after a freeze: a herd that has been short needs more than its daily requirement, and more time standing at the tank to get it.

So the failure is rarely the morning the tank freezes. It is the morning after, when demand spikes into a system that was sized for an average day.

The snow question, answered properly

The received answer is that snow is not water. The research is more interesting than that.

Cattle can meet their water requirement from snow, and controlled work has found no deterioration in weight or body condition against cows on open water. That is a real result and it is worth knowing before you panic on a Sunday.

The conditions attached to it are where most outfits fall out:

• It is learned behaviour. Some cows take four or five days to work it out, and adapting a herd properly is a matter of seasons, not one bad week.
• The snow has to be soft and clean. Ice-crusted, wind-blown or trampled snow does not do it.
• They have to be in condition. Body condition score four or better; thin cows should not be asked to do it at all.
• It takes roughly thirty to forty pounds of snow per cow per day, which is a great deal of snow across a great deal of ground.

Snow is a genuine backstop for the two or three days a tank is frozen and you are working on it. It is not a plan, and it is emphatically not a plan you adopt in the middle of the winter you need it for.

What the heater actually costs to run

A submersible element for a 100 to 300 gallon tank is generally 1,000 to 1,500 watts. Smaller tanks get by on 250 to 500.

Reported running costs sit around $30 to $80 per tank per month across a winter. In mild conditions a bare galvanised tank has been measured near 8.5 kilowatt hours a day; in a bad stretch it can approach thirty, which at ordinary rates is a few dollars a day per tank.

Notice where that variance lives. It is not in the heater — a 1,500 watt element is a 1,500 watt element. It is in how much of that heat ends up in the water instead of the air and the ground. Insulation and wind exposure move the figure twenty to fifty percent, and across four months and several tanks that is real money. It is also the cheapest item on this page to fix.

What to do this month

• Work out your own gallons per day. Head count, weight, production stage. Write it down.
• Time the refill on every tank with a bucket and a watch. Capacity is not the constraint; recovery is.
• Test every heater and every cord now, in daylight, standing up. Not in January with a torch in your teeth.
• Insulate the tank and what it sits on. Heat leaves through the ground as readily as the surface.
• Look at the approach. Ice builds where they stand, and a tank they will not walk to is the same as a tank that is frozen.
• Decide the backup before you need it, and know which tank you are hauling to.

What we are testing this winter

Tank heaters, insulated tanks and energy-free waterers, on our own meter. When those reviews run they will say what was used, for how long, in what weather, and what the electricity came to — and where we have not tested something, the page will say so before you read a word of it.

Sources

Water intake figures from SDSU Extension. Snow research summarised by Utah State University Extension and the Beef Cattle Research Council. Figures here are a starting point for your own arithmetic, not a substitute for it.