Which bottle your EcoTank takes: 502, 522 or 542

Go by the exact model number on your printer, not by how it looks. Epson lists the ET-2800 for 522 bottles and the ET-2850 for 502 bottles. The same split runs through other neighboring numbers. The ET-2720 takes 522, while the ET-2700, ET-2750 and ET-2760 take 502.

A third four-color family, 542, is all-pigment ink for the EcoTank Pro and WorkForce models in the last row of the first table below. Each family comes as one bottle per color, plus multipacks. If your model isn't in that table, Epson doesn't list it for 502, 522 or 542. To confirm any model, pick it in Epson's Ink Finder. The result lists the bottles Epson sells for it.

These lists come from Epson's US page for each bottle family. Epson sells some of these printers under the Expression or WorkForce name. Some models are listed twice, as Black and as White. That is the color of the printer, not a black-and-white model. Others appear as Business or Special Editions. All of these use the model numbers shown here. Epson's Ink Finder also lists Certified ReNew (refurbished) units under the same numbers.

These neighboring numbers take different bottles. Every entry comes from the same Epson lists.

The same thing happens further up the range. The ET-15000 takes 502, while the EcoTank Pro ET-16600 and ET-16650 take 542.

If you are trying to tell an ET-2800 from an ET-2850, two-sided printing is one difference. Epson's ET-2850 spec sheet lists automatic 2-sided printing. The ET-2800 guide has you flip the paper by hand for two-sided jobs. The model number is still the check to rely on.

Epson lists the 502 and 542 black bottles at 127 mL and their color bottles at 70 mL each. All four 522 bottles are 65 mL.

Page yields are a different matter. Epson states them on each printer's page or spec sheet, and the same bottle carries different figures on different models. The 522 black bottle is rated at 4,300, 4,500 or 4,700 pages depending on the printer, and the 502 black bottle at 7,500 or 8,500. Use the row for your own model.

To check the figure for your printer, open Epson's page for your bottle family, find your model under Works With and click View Ink Yields. That opens the printer's specifications. If the yield isn't shown there, open the Product Specifications PDF linked in that section.

Epson rates bottle yields on the ISO/IEC 24712 test pattern, using its own method adapted to tank printers. The color figure is an average across the three color bottles. Epson notes that yields can be lower if you print infrequently or mostly in one color. All colors are used for printing and for maintenance, and every color must be installed to print. Epson also cautions against comparing printers by milliliters of ink, so read the mL figures as bottle sizes. The bottles that come with a new printer yield less, because part of that ink charges the print head at setup.

To turn your model's yield into a cost per page, use the cost-per-page division. If you print only a few pages a month, see buying a printer for light use.

Go by the color name, not the number alone. The part-number tables in Epson's ET-2800/ET-2803 and ET-4800 user's guides pair 522220 with yellow and 522420 with cyan. Epson's 522 bottle pages, and the ET-2400 and ET-2840 guides, pair them the other way: T522220-S is the cyan bottle and T522420-S is the yellow one.

Epson's guides say the bottles are keyed for each color. They tell you to match each bottle to the color-coded sticker on its tank. They don't say whether a bottle from another family would fit, so don't count on the bottle to catch an ordering mistake. The ET-2800/ET-2803 and ET-2850 guides both say to use ink bottles with the correct part number for the product.

Epson also describes EcoTank printers as an open system that does not block non-Epson bottles. Its guides say Epson's warranties do not extend to damage from third-party ink or ink not designed for your printer.

Some 542 printers carry an added warning. Epson's pages for the EcoTank Pro ET-5800, ET-5850, ET-5880, ET-16600 and ET-16650, and its spec sheets for the WorkForce Pro ST-C5000 and ST-C5500, say the printer is designed for pigment inks only. They warn that dye inks may cause damage the Epson limited warranty does not cover.

• The tanks, not just the gauge. The ET-2800 guide says the printer estimates remaining ink from usage rather than measuring it. It warns that using the printer with ink below the lower line on a tank could damage it.
• The model number. Your computer's printer list (Printers & scanners in Windows) shows the printer by its product name. A network status sheet also shows the model name. On the ET-2800 you print it from Settings > Network Settings > Print Status Sheet; other models' guides give their own path. If any tank is below its lower line, don't print a status sheet. Use the name in your computer's printer list instead.
• Whether the number is in the tables above. If it isn't, Epson doesn't list it for 502, 522 or 542. Epson's 552 page lists the EcoTank Photo ET-8500 and ET-8550, with six bottles. In that family T552020-S is black and T552120-S is photo black. Epson's T512 page lists the Expression Premium ET-7700 and ET-7750. For any other model, use Epson's Ink Finder.
• The date on the package. The ET-2850 and ET-2980 guides say to use the ink by the date printed on the package.
• Whether your model uses a maintenance box. Open the ink part-number topic in your model's user's guide. The ET-2840 guide titles it Ink Bottle and Maintenance Box Part Numbers and lists box C9344. The ET-2980 guide uses the same title and lists T04D100. The ET-2800/ET-2803 and ET-2850 guides title it Ink Bottle Part Numbers and list no maintenance box.

If your Epson takes cartridges rather than bottles, this page doesn't apply. See Epson cartridge numbers and confirming the right cartridge.