If you are wondering which ink cartridges you can refill, take a look below at the cartridge numbers.  The cartridge numbers are the numbers that you can see on the actual inkjet cartridge and not your printer model.

Canon

Black Ink Cartridges
PG-40, PG-50, PG-510, PG-512, PG-540, PG-545, PG-560, PGI-525
 

Colour Ink cartridges

CL-41, CL-51, CL-511, CL-513, CL-541, CL-546, CL-561, CLI-526

HP

Black Ink cartridges

HP 300, HP 300XL, HP 301, HP 301XL, HP 302, HP 302XL, HP 303, HP 303XL, HP 304, HP 304XL, HP 305, HP 305XL

HP 336, HP 337, HP 338, HP 364, HP 901

Colour Ink Cartridges

HP 300, HP 300XL, HP 301, HP 301XL, HP 302, HP 302XL, HP 303, HP 303XL, HP 304, HP 304XL, HP 305, HP 305XL

HP 364, HP 901

Epson

Epson ink cartridges can be refilled, however there is a downside to using the existing ink cartridges. 

You will need to purchase a chip resetter to reset the chip on the ink cartridge (this is only successful if the cartridge still has around 25% of ink left in the cartridge)

Which is the best way to refill Epson ink cartridges?

In reality the best way is to not actually refill the existing Epson ink cartridge, but purchase purpose made refillable Epson ink cartridges. This makes the whole process easier and more reliable as the ink cartridge have plugs you open on the cartridge to carry out refilling. After refilling simply replace the plug and refit in your printer. This type of refillable cartridge will also have an “Auto Reset” chip, so there is no need to purchase a chip resetter.