What each water jug or liter of agua fresca really costs you (and how to calculate it)

The real cost of a water jug or a liter of agua fresca is calculated by adding the ingredients of a batch at average cost, plus the share of electricity, filters, gas and labor that batch consumes, and dividing the total by what actually came out ready to sell after waste. That number, not the price you paid for your last bag of sugar, is the one to use when you set prices. A spreadsheet is enough to start; what matters is using real data and repeating the math every month.

A quick note on terms: in Mexico the 20-liter returnable water jug is called a garrafón, and agua fresca is a sweetened drink made from fruit or flowers, such as hibiscus. We use both words below.

The four parts of your cost

Every product that leaves your plant carries four kinds of cost. If you miss one, your cost comes out lower than it really is and your margin is smaller than you think.

1. Direct ingredients: whatever the recipe uses. Hibiscus flower, sugar, fruit, treated water.
2. Single-use packaging: bag, bottle, cap, label, safety seal.
3. Production overhead: electricity, gas, filters, membranes, UV lamp, cleaning chemicals and plant labor.
4. Waste: whatever gets thrown out, spilled, rejected or is not enough to fill a complete product size.

The returnable garrafón itself is not a cost of each fill: it is an asset you use many times. What is a cost is replacing the ones that get lost or break. If you do not track that, read how to keep track of the jugs you lend.

Average cost: why it beats the last price

Ingredient prices change. If you calculate your cost with the last purchase price, your number jumps every time you buy, and it rarely reflects what is actually sitting in your storeroom.

Weighted average cost solves that. It is calculated like this:

Average cost = (stock on hand × previous cost + quantity bought × purchase cost) ÷ total stock

Suppose, as an example, that you have 20 kg of sugar that cost you $24 per kilo and you buy 50 kg at $30 per kilo:

• What you already had: 20 × $24 = $480
• What you bought: 50 × $30 = $1,500
• Total: $1,980 for 70 kg
• Average cost: $1,980 ÷ 70 = $28.29 per kilo

If you used the last price, you would say your sugar costs $30, and if you used the first, $24. Neither one is what the sugar you will use tomorrow actually cost you. The average is.

Yield and waste: what really comes out to sell

The recipe says a batch yields 100 liters, but you almost never get exactly 100. Some spills when moving from one pot to another, samples are set aside, a bag bursts in the sealer.

That is why it helps to separate two numbers:

• Expected yield: what the recipe says.
• Actual yield: what was actually packed and ready to sell.

The difference is waste. Write the expected waste into the recipe and the actual waste into each batch. If the actual number is always higher, you have a process problem worth looking into, because every lost liter makes all the others more expensive.

Example: a 100-liter batch of hibiscus agua fresca

Every number in this example is illustrative. Use your own.

Batch ingredients, at average cost:

• Hibiscus flower: 1.5 kg × $160 = $240
• Sugar: 8 kg × $28 = $224
• Purified water: 100 L × $0.30 = $30
• Total ingredients: $494

Overhead the batch consumes:

• Gas and electricity for preparation: $40
• Labor: 2 hours of one person × $70 = $140
• Cleaning and sanitizer: $16
• Total overhead: $196

Total batch cost: $494 + $196 = $690.

Now the yield. The recipe expects 100 liters, but 96 liters were packed; 4 liters were waste.

• If you divide by the expected yield: $690 ÷ 100 = $6.90 per liter.
• If you divide by the actual yield: $690 ÷ 96 = $7.19 per liter.

The difference looks small, but if you make several batches a week it adds up. Always use the actual yield.

Finally, packaging. If you sell in 1-liter bags and each bag costs you $1.20, each bag of hibiscus agua fresca costs $7.19 + $1.20 = $8.39.

Example: the cost of a 20-liter garrafón

At a water purification plant, water is not made in recipe batches like agua fresca but continuously. That is why it is more practical to calculate the cost per month and divide it by the garrafones filled that month.

Suppose, as an example, a month in which you fill 3,000 garrafones:

• Plant electricity: $4,500
• Filters, membranes and UV lamp, prorated per month: $1,800
• Softener salt, chlorine and soap to wash jugs: $900
• Mains water or tanker water: $1,500
• Plant labor, filling and washing: $15,000
• Monthly total: $23,700

Plant cost per garrafón: $23,700 ÷ 3,000 = $7.90.

Then add what goes out with each garrafón:

• Seal and cap: $1.50, bringing the cost to $9.40.
• Replacing lost garrafones: if you lose 40 a month and each costs $90, that is $3,600 ÷ 3,000 = $1.20 per garrafón, and the cost ends at $10.60.

Note that this is the cost of producing the garrafón, not of delivering it. Gas, the driver and wear on the truck are route costs and are best looked at separately. If you are setting up the business from scratch, we cover those costs in how to start a water purification business with delivery.

Cost per batch versus cost per liter

They are two different numbers and both are useful:

• Cost per batch tells you how much money went into one production run. Use it to compare batches and to value what you have in the warehouse.
• Cost per liter tells you what each unit you sell costs you. Use it to set prices and work out margin.
• Cost per product size is the cost per liter times the liters in that size, plus its packaging.

The most common mistake is dividing the batch cost by the expected yield instead of the actual one. The second most common is leaving out overhead because "the electricity gets paid anyway". It does get paid anyway, but your product is what pays it.

In Repartamos the recipe shows the estimated cost per batch and per liter using the current average cost of each ingredient, and every completed batch keeps its actual cost.

How to use your cost to set prices with VAT included

If your shelf prices include VAT, part of what you charge is not yours. To know your real margin, take the VAT out first:

Price before VAT = price with VAT ÷ (1 + VAT rate)

The rate depends on the product and how you sell it, so confirm it with your accountant for each product size. Here are two cases with the hibiscus bag that costs $8.39 and sells for $15:

• At a 16 % rate: $15 ÷ 1.16 = $12.93 before VAT. Margin: $12.93 − $8.39 = $4.54 per bag, 35 % of the price before VAT.
• At a 0 % rate: the full $15 is yours. Margin: $15 − $8.39 = $6.61, or 44 %.

That margin still has to pay for delivery, rent and your own salary. If nothing is left after subtracting everything, you need to raise the price, lower costs or stop selling that product size on that route.

How often to recalculate

• Ingredient cost, with every purchase.
• Overhead, once a month, using the actual bills.
• The full recipe, whenever you change supplier, formula or product size.
• Your prices, when costs rise noticeably or every three to six months.

If you do all of this in a notebook or across several spreadsheets, in notebook, Excel or software for your water business we compare when each option makes sense.

Quick checklist

• Add up ingredients, packaging, overhead and waste.
• Use average cost, not the last purchase price.
• Divide by the actual yield, not the expected one.
• For purified water, calculate per month and divide by the garrafones filled.
• Include the replacement of lost garrafones.
• Keep production cost separate from delivery cost.
• Calculate margin on the price before VAT.
• Recalculate overhead monthly and review prices every three to six months.