Machines That Should Not Be Backflushed

You've read that backflushing is good for a group head, and now you're holding a blind basket and wondering. Don't lock it in yet. On some machines this job can do harm.

Why it can hurt

A blind basket blocks the water. On a machine with a three-way solenoid valve, the pressure has a way out. One guide says only machines with that valve can be backflushed¹.

Without the valve, there's nowhere for the water to go. The same guide says forcing a backflush can damage the machine¹. A second guide says the blind basket then just traps hot, pressurized water against the group². It adds that the job won't clean anything and can put stress on the machine. Hot water and grounds can also spray out when the portafilter comes off².

That retailer's advice is blunt: don't backflush a machine without a three-way valve². It's one retailer's view, so follow your own maker's manual, which decides for your machine.

How to find out from the manual

The manual settles it fastest. It should either give backflush steps or tell you plainly not to do it².

Here's how to look:

1. Find the cleaning or maintenance section, not the setup pages.
2. Look for the words "backflush", "back-flush", "blind basket" or "blind filter".
3. Look for a warning in the same section that tells you not to.
4. If the machine has a built-in cleaning program, read that part too.

If you find backflush steps, the blind basket steps page shows how to read them. If you find a warning, or nothing at all, treat that as no.

Don't rely on a hint

A blind basket supplied with the machine counts as a strong hint, but no more². Your manual settles it.

Machines with their own cleaning cycle

Some machines don't need you to fit a blind basket by hand. Fully automatic machines are one case. One retailer's guide lists superautomatics as ones with their own cleaning cycles that shouldn't be backflushed¹.

Some machines without a three-way valve also include their own cleaning program. Those cycles are built around the machine's own internals. That retailer says to stick to the manual and its listed products².

One maker's manual shows the sort of thing to expect. Its cleaning cycle needs a supplied cleaning disc and a cleaning tablet in the filter basket, and the portafilter locked into the group head³. That's the maker's method for that model. It isn't a recipe for another machine.

What to do instead

If your manual says not to backflush, you still need to clean the group head. Your maker's manual decides what cleaning is right for your machine. If it doesn't say, ask the maker or a qualified technician rather than taking parts off yourself.

Don't open the machine yourself. If a fix needs the case off, or reaches the wiring or the valve, call the maker or a qualified technician.

Whichever method your machine uses, the manual should also say how often to do it.