Nine tenths of it comes back out
A hundred gallons of milk at 8.6 lb a gallon is 860 lb. Ten percent of that leaves as cheese, so 774 lb — 90 gallons — leaves as whey. It is the biggest single thing that comes out of a make and it arrives all at once, at the moment the vat is drained, in a room that has to have somewhere to put it.
Per pound of cheese it is 1.05 gallons of whey for every pound off the press. That ratio is the one worth remembering, because it makes the whey a variable cost of the cheese rather than a nuisance that happens afterwards.
What the mass balance leaves out
The sum is milk in, cheese out, the rest is whey, and it counts nothing else. Salt going in, rinse water, wash-down, anything added after the curd is lifted — all of that also ends up in the same tank and none of it is in the 90 gallons. If your whey tank consistently gauges higher than this figure, the gap is water, and knowing how much of it there is changes what a load costs you, because a hauler charges to move water at exactly the same rate as whey.
Part loads, and the case for holding it
Ninety gallons into a 300 gallon tanker is 0.3 of a load, and you pay for the whole thing. Two makes a week hauled separately is two loads and 420 gallons of paid-for air. Hold the week and haul once and it is 180 gallons in one load — one load instead of two, 65 dollars instead of 130, and 3,380 dollars a year.
Batching can never cost more loads than hauling each make, because rounding up once beats rounding up twice. That is arithmetic and it is safe to rely on. What is not safe to rely on is the assumption that holding it is free. It needs a tank that takes 180 gallons, floor space for the tank, and a view about what whey does while it sits, particularly in July. The page prints the load saving and stops there, because the other side of that decision is not arithmetic.
Per pound, which is where it should have been all along
One load a week across two makes is 32.50 dollars a make, which is 3.78 dollars per hundredweight of milk and 38 cents per pound of cheese off the press. Per aged pound it is more again, because the wheel gets lighter in the cave while the whey bill does not.
Thirty-eight cents a pound is not a rounding error on a small cheese, and almost nobody has it in their costing, because the invoice arrives weeks later with a hauler name on it and never gets attributed back to the make it came from. Working it out once tends to change how somebody feels about a point of yield, since a point moves the cheese up and the whey down at the same time.
The part that is not arithmetic
Where whey may go is regulated, and small dairies are exactly the case where people assume it is not. Drains, septic systems, watercourses and land spreading are all governed by somebody, the rules differ by country, state and county, and whey has a high oxygen demand which is why the rules exist. The land block on this page divides gallons by a rate you supplied off your own plan or permit. It is a division. It is not a permission, and no calculator can give you one.
Questions people ask
How much whey comes off a cheese make?
Milk in minus cheese out. A hundred gallons of milk at 8.6 lb a gallon with a ten percent green yield leaves 774 lb of whey, which is 90 gallons. Roughly 1.05 gallons of whey for every pound of cheese off the press. The sum is a mass balance, so it counts none of the rinse water or wash-down that also goes in the same tank, and real tanks usually gauge higher than it for that reason.
Is it cheaper to haul whey every make or hold it for a week?
Holding it is never more loads, because a part load rounds up whichever way you do it and rounding up once beats rounding up twice. Two makes of 90 gallons into a 300 gallon tanker is two loads if hauled separately and one if held — 65 dollars a week and 3,380 a year. What that ignores is the tank, the floor space and what whey does while it sits, and on a warm week that last one usually decides it.
What does whey disposal cost per pound of cheese?
On the figures in the form, 38 cents per pound off the press — one 65 dollar load a week across two makes, 86 lb of cheese each. Per aged pound it is higher, because the wheel loses weight in the cave and the haulage does not. It is a genuine cost per pound of product and it almost never appears in a small dairy costing, because the invoice arrives weeks after the make.
Can I put whey down the drain or on my fields?
That is not a question this page answers, and it is not a question to answer by assumption. Discharge to drains, septic systems and watercourses is regulated, land application is normally a permitted activity with a nutrient management plan behind it, and the rules differ by country, state and county. Whey has a high oxygen demand, which is why the rules exist. Ask the authority that regulates your discharge before your first make.
How much land does spreading whey need?
Annual gallons divided by the rate per acre your own plan allows. At two makes a week that is 9,360 gallons a year, and at a plan rate of 12,000 gallons an acre it is 0.78 acres. The rate is a field on the form because it comes from your nutrient management plan or your permit and from nowhere else. This page holds no rate of its own and the division is not an approval.