Though you might complain about paying $15 for avocado toast at brunch, the true cost of your breakfast is probably even more expensive than that, especially in terms of the environment. According to an analysis from The Crunch, a new initiative from the Wellcome Trust, it takes 68 liters of water to make a full English breakfast, beans, sausage, and all—that’s about as much water as it takes to fill a bathtub. If anything, the amount of water you consume at breakfast is higher than you’d think, because the real environmental cost is embedded in the food that you eat.

The amount of water used to grow, transport, and prepare is a metric called virtual water, and it makes up a significant portion of global water consumption. In fact, about 92 percent of all the water humans consume is used to produce food, according to Dr. Esther Delbourg, an economist and consultant on water change and climate issues, in a video from the Wellcome Trust. And in the face of increasingly frequent droughts, like the one currently taking place in California, it’s important to understand how expensive your food really is. One tomato, for example, costs six liters of so-called virtual water, or 1.5 gallons. One potato costs 15 liters, or about 4 gallons, of virtual water, and a glass of wine is 120 liters, or 31 gallons.

And unfortunately, your breakfast isn’t exempt from making an impact on the environment. A bowl of corn flakes with semi-skim milk uses ten liters of water, or 2.2 gallons, but that pales in comparison to the amount of water used to make that full English breakfast or even a bacon roll, which uses about 30 liters of water, about 8 gallons.

The most environmentally friendly breakfast named by the Wellcome Trust is also the simplest. A piece of whole-grain toast with jam only uses four liters, or about a gallon, of water.

Everything you eat has an environmental cost, though some foods are more sustainable than others, and you can see how your breakfast stacks up in the infographic from The Crunch below.