What Ink Does the Epson EcoTank ET-3843 Use?

Quick answer: the Epson EcoTank ET-3843 uses Epson 502 ink bottles — not cartridges. Four bottles, one per tank, and there is no XL or high-yield version, because the 502 family ships in one size only.

The wrong answer people land on for this printer is Epson 522, and it is an expensive mistake in both directions. Epson's own 522 compatibility list runs to fourteen models and the ET-3843 is not among them. Worse, 522's black bottle is smaller than 502's — so buying 522 gets you ink that does not fit and less of it.

Part of the blame sits with retailers. Amazon's 502 listing titles read "ET-2750, 2760, 2850, 3750, 3760, 3850, 4850, and other select models" — the ET-3843 lives inside "other select models", so shoppers scanning the title conclude 502 is wrong for them and go hunting. It is not wrong. It is the only ink this printer takes.

Epson EcoTank ET-3843 ink at a glance

Those volumes and yields come from Epson's own specification sheet for this printer. Worth knowing: Epson's retail ink pages only say "thousands of pages" — the actual numbers live in the spec sheet, so if you check the ink listing and find no figure, that is expected rather than a contradiction.

One ordering trap in Epson's own part numbering: the four-color pack is T502120-BCS, which begins with the black bottle's stem, while the three-color pack is T502520-S. Two packs, two unrelated-looking numbers. Read the suffix, not the stem.

What it actually costs to run

Castle Ink's compatible 502 four-pack is $38.95. Against Epson's 7,500-page rating for the black bottle on this printer, that lands at roughly 0.3 cents per black page once you apportion the black bottle's share of the pack. A cartridge-based all-in-one in the same class runs 10 to 15 cents.

Concretely: 7,500 pages of black text costs about $15 of ink here. The same 7,500 pages on an entry-level cartridge printer runs past $750. That single comparison is the entire argument for a tank printer, and you can check it against your own volumes with our ink cost calculator.

Castle Ink recommendation

Castle Ink stocks a compatible Epson 502 four-pack (BCMY) for $38.95, guaranteed for a year. One pack fills all four tanks.

Two shopping warnings for this family. First, sublimation bottles are routinely titled "502 / 512 / 522" together — they physically fit the ports but they are a heat-transfer ink chemistry and do not belong in a document printer. Second, plenty of sellers title 502 items as "ink cartridge". This printer takes bottles; there is no 502 cartridge to find.

How to refill the tanks properly

1. Wait until the printer tells you a tank is low. Do not top up early — once ink is mixed you cannot judge the level accurately.
2. Open the tank cover and unlock the cap for the color you are filling.
3. Hold the bottle upright in the port. Epson's design meters the flow and stops when the tank is full, so there is no need to squeeze.
4. Fill all the way to the top line. Epson is specific about this because the reset step assumes a full tank.
5. Close the cap firmly, then select the colors you refilled on the LCD and complete the on-screen reset.

Never let a tank run below its lower line. Epson warns that continuing to print below it can damage the printer — and never mix colors between ports, which means a full ink-system flush at best.

About the Epson EcoTank ET-3843

The ET-3843 is a home-office EcoTank: print, scan and copy, with a 30-sheet automatic document feeder, automatic two-sided printing and a 250-sheet paper cassette. There is no fax — that sits on the ET-4850 and ET-4800 in this generation.

Rated at 14 ISO ppm black and 7 ppm color, dropping to about 6.5 and 4.5 with duplex enabled. The display is a 2.4-inch color LCD driven by physical buttons; Epson's own spec sheet calls it a touchscreen, but the User's Guide documents arrow keys, an OK button and an on-screen keypad, so treat the touchscreen line as an error. Connectivity is Wi-Fi 802.11 b/g/n — 2.4 GHz only, no 5 GHz — plus Wi-Fi Direct, 10/100 Ethernet and USB.

Epson has discontinued the ET-3843, and its sibling ET-3830 with it. The current equivalents are the ET-3943, ET-3950 and ET-3958, all of which take the same 502 ink — so an ET-3843 is a machine to keep running, not a dead end for supplies.

Common problems on this model

Faint or missing colors after the printer sits idle

The dominant complaint on this family, and it is a dried-nozzle problem rather than an ink problem. Run a nozzle check, then a print head cleaning. If gaps remain, use Maintenance > Power Cleaning — but read Epson's two conditions first: every tank must be at least one-third full (running it low can damage the printer), and after one Power Cleaning you must power off and wait at least 12 hours before running another. It also consumes a lot of ink. Printing one color page a two weeks prevents most of this; see whether ink dries out.

Ink levels wrong after refilling

The printer estimates levels by counting usage, not by measuring the tanks. Refill to the top line, select the colors you filled on the LCD and complete the reset — otherwise the gauge keeps reporting the old figure. Inspect the tanks visually rather than trusting the display.

ADF will not feed, or copies come out streaked or shifted

Check that the ADF icon lights on the Copy or Scan screen — if it does not, the printer has not detected the originals, so reload them. Do not load above the arrow mark on the edge guide, flatten curled or creased pages, and clean the inside of the ADF and the scanner glass. For shifted margins, also align the original to the corner symbol on the glass and set the correct Original Size in copy settings.

Maintenance box message

The ET-3843 routes waste ink from head cleaning into a replaceable maintenance box, part number T04D100, around $11 from Epson. When it fills the printer stops. This is a genuine consumable and it is user-replaceable on this model, which is a real advantage over the cheaper ET-2800 and ET-4800 class, where the waste pads are not owner-serviceable.

Will not join Wi-Fi, or setup stalls

This printer is 2.4 GHz only. If your router broadcasts one merged network name across both bands, Epson's own guidance is to enable dual-band mode with separate SSIDs per band so the printer can see a 2.4 GHz network to join. Epson also currently carries an advisory that its Windows 11 installer can stall on this model; where the full driver will not install, Windows 11's built-in driver picks the printer up automatically once it is on the same network or attached by USB. Our printer Wi-Fi setup guide covers the Epson path in detail.

FAQ

What ink does the Epson EcoTank ET-3843 use?

Epson 502 ink bottles in black, cyan, magenta and yellow. Nothing else fits.

Does the Epson EcoTank ET-3843 use Epson 522?

No. Epson's 522 compatibility list does not include the ET-3843, ET-3830 or ET-3850. It covers the ET-2800, ET-4800, ET-2903 and similar. The two families are not interchangeable.

Is there an Epson 502XL?

No. There is one bottle size. Epson markets 502 itself as ultra-high capacity, which is branding on the base product rather than a separate tier.

Which other printers use Epson 502?

The nearest cross-fits are the ET-3830, ET-3850, ET-3760, ET-4850, ET-4950, ET-2850, ET-2980, ET-15000 and the current ET-3943, ET-3950 and ET-3958. Epson's full list runs to more than twenty models.

Can I use compatible 502 ink without voiding the warranty?

Yes. US law prevents a manufacturer voiding your warranty purely for using third-party supplies. See the legal answer.

Does the ET-3843 have a fax?

No. It prints, scans and copies, with an ADF and automatic duplex. Fax in this generation is on the ET-4850 and ET-4800.

Is the ET-3843 still made?

No, Epson has discontinued it — but 502 ink is current and widely stocked, and the replacement ET-3943, ET-3950 and ET-3958 all use the same bottles.

Shop Epson 502 ink now

Grab the 502 four-pack. Different printer? Find yours on our Find Ink by Printer page, or see how your model ranks on running cost in the monthly CastleScore rankings.