How to Properly Flush a CISS System: Should Water Run Through All Ink Lines Including White?

Question:
When flushing or running water through a CISS (Continuous Ink Supply System), should the water be run through all ink lines, including the white ink tank that currently has water in it, or should certain colors be handled differently?

Answer:

When it comes to flushing a CISS system, the short answer is: no, you should not treat all ink lines the same, and this is especially true for white ink systems.

For standard CMYK colors (cyan, magenta, yellow, and black), running distilled water or a proper flushing solution through the CISS lines is generally acceptable during cleaning, storage preparation, or ink conversion. These dye- or pigment-based inks tolerate water-based flushing reasonably well, as long as the system is later dried or refilled correctly.

However, white ink is a completely different case. White ink contains heavy pigments (typically titanium dioxide) that settle quickly and are far more sensitive to contamination. Running plain water through a white ink line-especially one designed for DTF or DTG use-can cause several serious problems:

• Pigment separation and residue buildup, leading to clogs that are much harder to clear later

• Chemical incompatibility, if residual water mixes with white ink later

• Internal corrosion or sensor issues, depending on the printer design

• Permanent damage to dampers, pumps, or the printhead, particularly if water remains trapped in the system

If the white tank currently contains water, that typically indicates the system is being stored, tested, or temporarily flushed-but this should only be done with proper white-ink-safe cleaning solution, not regular water, and only for specific purposes. In most cases, white ink lines should be flushed separately and with extreme caution. They should also never be left stagnant for long periods, as this increases the risk of sediment settling and hard clogs.

In practical terms:

• CMYK lines: Yes, these can usually be flushed with distilled water or cleaning fluid when appropriate.

• White ink line: No, do not casually run water through it unless you fully understand the downstream effects and are using the correct flushing chemistry designed for white ink systems.

If white ink maintenance is done incorrectly, it often leads to issues that cannot be resolved through software cleaning cycles and may result in costly component replacement.

Addressing printer issues can be a complicated affair due to the hands-on nature of these systems. Because of that, we're not able to provide remote troubleshooting, suggestions, or direct support for printer repairs. We do, however, offer an in-person evaluation and repair service through our local diagnostic facility at Printer Repair Service by BCH Technologies (https://bchtechnologies.com/printer-repair-service). Due to high demand, repairs are handled on a first-come, first-served basis, and it may take several weeks before a drop-off slot is available. Our services can cover either full-printer repairs or specific components, with clear instructions provided ahead of time. While our pricing may not be the most economical, we aim to be thorough and transparent.

That said, we strongly encourage self-help through online research. A great place to start is YouTube, particularly our BCH Technologies YouTube channel (https://youtube.com/@bchtechnologies). You can use the search icon near the "About" section on the right-hand side of the channel page to locate videos on specific topics. I receive dozens of questions every day asking whether a particular video exists, and after more than nine years of creating content, it's not realistic to remember every single one. Using YouTube's search function is the fastest and most effective approach, and it may also surface helpful videos from other creators.

Thank you again for reaching out and for your continued support. We truly appreciate your patience and your engagement with BCH Technologies.