For espresso machines, backflushing only works on machines with 3-way valves (like the Silvia), or with a manual backflush valve (like some of the E-61 equipped ECM machines). The 3-way is a valve, normally electromagnetically controlled, that relieves pressure in the portafilter when the brew switch is turned off. Backflushing pushes the cleaning agent back through the showerhead and brewing group then through the 3-Way valve. If your machine does not have a 3-Way valve you should not backflush unless your manufacturer specifically recommends it. See your owner's manual or contact your machine's supplier or manufacturer for more information. To learn more about how a 3-way valve works and why backflushing is important to the inner workings of an espresso machine, see my illustrated presentation of "3-way Valve Hows and Whys."

      Why backflush? When the 3-way valve opens to relieve the back pressure in the brewing path, it allows some coffee residue and grounds to pass through that path. This grounds and oils can build up in the brewing group which can eventually add a stale taste to the coffee. The grounds can also build up to the point that the 3-way valve stops operating properly. So, why put a 3-Way valve on a machine at all? It relieves the pressure in the portafilter as soon as the brew switch is turned to the off position, and this keeps you from getting a face-full of hot grounds mixed with near-boiling water when removing the portafilter.

      But backflushing is only part of the job. Sure, backflushing cleans out the passages in the showerhead that go between the portafilter and the 3-Way valve, but there are other parts in there that get dirty too. Specifically these are the shower screen, dispersion device, all their related hardware, the filter basket, the showerhead itself, and the portafilter body and its spout. Once you start in at cleaning by backflushing you might as well clean all these parts, because any of them, if left dirty, can add bad tastes to the coffee. Based on that, these instructions outline all the steps necessary to get all these parts clean.

      In my opinion, when done properly and with due care, backflushing does not put any more stress on a machine than it experiences when you pull a shot with coffee that has been ground too fine which chokes the machine.

MATERIALS: Besides your espresso machine's brewing parts you will need:

Espresso machine cleaner - There are many types. The stuff that is best for cleaning the brewing parts is not necessarily to be used in the rest of the machine. That is, do not run espresso machine cleaner through the water tank and the pump unless the instructions say that it can be used this way. I like using Urnex Cafiza for backflushing. Be aware that it specifically states that it is not to be used in the water tank. It is excellent for removing coffee residue, oils, grounds, etc. It is also not compatible with aluminum parts. Again, it is important to read all instructions and warnings on cleaners and be sure that it is approved by your machine's manufacturer before proceeding.

A blind filter basket or a backflush insert - A blind portafilter is a filter basket that has no holes in it. It would obviously be no good for brewing espresso as there is no way for the water to go through it. The alternative to a blind filter is a special rubber insert that is placed in a standard basket and plugs it up much in the same way that one of the flat rubber sink stoppers work.

Glass bowl - This should be just large enough to hold the portafilter, showerhead parts (screen, dispersion device, screw, etc.) and the filter basket. You will mix the cleaner in this and allow the parts to soak

Grouphead Cleaning Brush - These stiff, angled brushes are designed to scrub the brewhead void where the portafilter gasket rests, but they are also great for scrubbing the portafilter and shower screen parts as well.

Sink and running water - To rinse all parts thoroughly after cleaning.

Ground coffee -To pull a shot after cleaning. Use old or inexpensive beans for this as you will want to discard this first.

2-Disassemble the portafilter: remove the basket, retaining spring, and if possible remove the handle (NOTE: On many portafilters the handle is either really tight, non-removable, or made out of thin plastic. In these cases it is best to just leave the handle attached and use a large enough soaking vessel that the handle does not have to be removed.). Soak all these parts in the cleaning solution as well. Once or twice during the soaking use a stiff brush to scrub all the parts to enhance the cleaning process. Follow the instructions on the cleaner as to how long it should soak.

3- If you have removed the shower screen and dispersion device, while the parts mentioned above are soaking, dip the brewhead brush in the cleaning solution and clean the brewhead, portafilter gasket, and as much of this area as you can reasonably access. This area is easy to clean with the shower screen off, and that way you are not sending that scum through the brewing path unnecessarily.

CAUTION:Use eye protection as the brush will splatter the cleaner about!

4- Scrub and rinse the shower screen and dispersion device and reinstall it on the machine. Their presence will help protect various parts of the machine from undue stress during the backflushing process. The screen can act to buffer the force of the water.

5- Turn on the machine and let it get warm. The cleaning solution works better in hot water.

6- When the remaining parts from step 1 are clean, remove and rinse them thoroughly. Reassemble the portafilter and place the blind filter basket (or if you are using one, the rubber backflush insert) in the portafilter body. You must have a basket in place in the protafilter becasue a seal cannot be established against the brewhead gasket without one.

7- Place the appropriate amount of cleaner in the filter basket on top of the backflush insert and add a little hot water to get it to start dissolving. As mentioned previously, if the directions for the cleaner differ, use the directions supplied with the product.

8- Lock portafilter in place

9- Turn on the brew switch and when the pump pressure builds, turn off the brew function. In most machines with tight seals, the pump will build pressure and begin to labor within two or three seconds. Do not let it do so for more than the briefest period of time necessary. It is not the pump's pressure that is going to do the cleaning but the presence of the cleaner in the brewing path where the dirt resides.

10- Wait a second or two, then repeat this on-off cycling of the pump until some suds formed by the cleaning solution are seen in drip tray. It usually only takes two or three on-off cycles to accomplish this. The presence of the suds in the drip tray shows you that the solution has made its way through the entire brewing path, through the 3-way valve, and is working for you. When this happens let the machine sit to soak for a few minutes. After about three to five minutes repeat steps 9 and 10. Continue this way until nothing but clean suds, void of coffee residue come from the 3-way valve. Cleaning out the drip tray between flushes helps you see if this has taken place.

11- Loosen the portafilter in the brewhead so it will leak just a bit. Now run the machine again to splash cleaner around the showerhead area. While the water is being pumped, wiggle the portafilter handle to cause the cleaning solution to be splashed about in the brewhead. If necessary, put a little more cleaning agent in the portafilter for this step.

CAUTION: cleaning solutions can be nasty stuff to eyes, children, pets, etc. Use care when doing these steps including having no spectators and using eye protection.

12- Remove the portafilter and pump some water through the machine to rinse off the shower screen and brewhead.

13- Rinse off the portafilter and blind filter and lock it back in place. Turn the brew switch on then immediately off a few times (using the precautions mentioned in step 9) until clean, clear water comes through 3-Way valve. You may need to dump out the drip tray a few times to be sure clean water is coming through. Do the loose-portafilter wiggle to flush the brewhead with clean water as you did in step 11.

CAUTION: Remember eye protection here as the brush will splatter the cleaner about.
CAUTION:These parts are now hot and the water coming from them can burn. Use care!

14- Remove the blind filter, replace the portafilter, and just using the water from the machine and no coffee in the basket, pull a blank shot through the machine for a final rinsing.

15- If necessary, rinse everything thoroughly again in hot water, including giving the showerhead a good scrubbing with the brush using clean, hot water.

16- When everything is rinsed as clean as possible, grind some coffee and pull a shot and toss it down the sink. This is to be sure that any remaining cleaning agent does not end up in a shot meant to be consumed.

      Even with regular backflushing there are places where coffee residue and oils can build up and cause problems. This is mainly in the 3-way valve. The only way to get it completely clean is to disassemble it and soak and scrub the parts individually. Doing so once or twice a year can help keep your machine working happily. The instructions for doing so are on David R. Jenkins' website on the page entitled Fixing a Leaky Solenoid on a Rancilio Silvia. This page was done well enough that I felt no need to duplicate his efforts.