Most of the time , users failed to ask / and Sellers negligently withheld information.
Let’s look at the risk of CISS systems:
a) As with all refilling, DIY refills always damage printhead.
You can read more here the 4 main reasons of printhead damage caused by refilling due to dirt.
It need to be warned that such CISS and DIY ink refill system had caused a unprecedented record number of printer (printhead) damage. Printhead lifespan had been shortened considerably due to DIY ink refill proliferation.
b) CISS ink tanks leaking non-stop: (above picture)
As the printer prints, the ink level will never be in perfect equilibrium.
When the pressure from the ink tank is higher, ink will leak through the cartridge. 1cm of height = 40ml of ink leak. Many CISS user find their printer soaked in a pool of ink the next morning.
c) CISS ink backflow into tank. Printhead damage. (above picture)
When the cartridge is higher level that the ink tank, the air pressure in ink tank is lower, ink will backflow into the tank, and air enters from the printhead into the cartridge. When the printer prints without any ink at the printhead, the printhead overheats and burn.
As there could never be perfect equilibrium, 1) immediately after setup, 2) when the printer is in motion (during printing), 3) following a refill procedure (the plugs are opened and then closed, some / sufficient amount of ink needs to leak out until negative pressure exist in the ink tank)
Are there savings using CISS?
Absolutely NOT. If you have purchased the right printer from the beginning. If you have chosen a Brother printer, you would have realized that Brother ink cartridges consist of disposable plastic container filled with ink. The compatible cartridge for Brother printers are approximately $5 which is cheaper than the bulk ink and labour cost charged by vendors to setup such a system.
However, there are indeed savings when using refill kits when the right type of cartridge is refilled (i.e. those with printhead) read more here
So at what instance would CISS be useful?
a) If you are a start-up running a printing house, but trying to save cost by printing on entry-level inkjet printer.
b) You print so much photos, several hundreds at each print job, so much so that it is a hassle to change cartridge.
c) And you can bear with occasional leaking.