How to Flush a CISS System Safely: Should You Run Water Through All Colors or Only the White Line?

Question

When I'm running water through my CISS system to flush it, am I supposed to run water through all the color lines too-including the white tank-or do I only run water through the white side?

Answer

For your question: No-you should not run water through all colors. You should run it through the white line/tank only.

Why you should flush only the white channel

White ink systems (whether DTF, DTG, or other setups) behave very differently from standard CMYK inks:

• White ink contains heavy pigment that settles quickly and can pack into lines, dampers, valves, and the printhead if it's not moving regularly.

• Because of that, the white circuit is often the first one that needs flushing during maintenance or troubleshooting.

• Flushing the CMYK (or other color) lines with water when you don't need to can actually create new problems, such as:

  • diluting inks and causing weak color output,

  • introducing air into otherwise stable lines,

  • changing ink chemistry (some inks don't react well to plain water),

  • causing more cleaning cycles and wasting ink to recover.

What "flushing with water" is really doing (and when it's appropriate)

When you run water (or any flush fluid) through the white portion of the CISS, you're typically trying to:

• clear out thickened white ink,

• remove sediment buildup,

• test flow and suction,

• or prep the white system for storage or a controlled refill.

That goal usually does not apply to your color channels unless you're doing a full conversion, swapping ink types, fixing contamination, or recovering from a major blockage.

Best practice tip: use the right fluid for the right job

Even though you asked specifically about water, it's worth noting that many systems do better with a proper cleaning solution rather than plain water-especially if you're dealing with pigment inks or DTF/DTG inks. Plain water can be helpful in certain situations, but it can also:

• leave corrosion risk if it sits in metal parts,

• encourage microbial growth if left stagnant,

• and sometimes isn't strong enough to dissolve dried ink residues.

So if your goal is cleaning/recovery, a printer-safe cleaning solution is often the more reliable option. If your goal is simply "rinse and test flow," water may be used in controlled situations-but again, only on the white circuit, as you stated.

Bottom line

• Run water through: white only.

• Do not flush all colors unless you have a specific reason and a controlled plan to re-prime and stabilize every channel afterward.

Addressing printer issues can be a complicated affair due to the hands-on nature of the problems, so we're not able to provide remote troubleshooting, suggestions, or support for printer repairs. We do offer an in-person evaluation and repair service through our local diagnostic facility: printer repair service (https://bchtechnologies.com/printer-repair-service). Because demand is consistently high, we operate on a first-come, first-served basis, and it may take a few weeks before we can schedule a drop-off. Our services are structured to repair either an entire printer or specific parts, with clear instructions on how to proceed. We also recognize our rates aren't the most economical, so we strongly recommend self-help through online research first. You can start by checking out YouTube or visiting our channel homepage, BCH Technologies on YouTube (https://youtube.com/@bchtechnologies). Look for specific videos using the search icon next to "About" on the right-hand side of the menu bar. I receive dozens of questions every day asking about videos for specific topics, and after creating videos over the past nine years, it's challenging to remember every single one. Using YouTube's search function is the fastest way to find the exact video you need, and YouTube may also suggest helpful videos from other channels that apply to your situation.

Thanks again for reaching out, and thank you for supporting BCH Technologies.