Pressure problems in Nespresso coffee machines

As we have already mentioned in this blog on other occasions, to prepare the perfect espresso, we need to fulfil a series of requirements regarding the coffee we use and how the coffee machine prepares it. Without going into too much detail, we can summarize that we need the following:

  • 7 grams of fine ground coffee
  • Water pressure of 9 bar
  • Infusion temperature of 86ºC
  • The preparation time of about 25 seconds (5 extra seconds of pre-infusion)
  • The final drink of 25 ml

By design, Nespresso coffee makers have a maximum pressure of 20 bar ± 3 bar. Still, these values refer to the design of the pump because, mounted on the Nespresso, it works between 9 and 16 bar, depending on the type of coffee used and the state of the coffee maker. When the pump delivers less than 9 bar during the preparation of coffee, we will obtain a far from a perfect result.

Causes for which the Nespresso loses pressure

Note: On very rare occasions, we are going to find a Nespresso that suddenly increases the water pressure, this would only happen in cases where we have connected our coffee maker to the wrong power supply, and therefore we discard it as a problem of the machine, and we will not deal with it in this article.

The lack of pressure in the pump is intimately linked to the loss of coffee volume in our cup, so the first symptom that our coffee maker is losing pressure can be found in the coffee we obtain. In this article, we saw the problem of too short-volume coffees.

As we saw in that article, the first thing you have to do is make sure that the coffee maker is losing pressure and that this is not just a subjective opinion. To do this, you must reset the machine to the factory settings, in which a volume of 40ml for espresso and 110ml for lungo is obtained.

  1. Disconnect the coffee maker.
  2. Press and hold the lungo button.
  3. Switch on the Nespresso.
  4. Release the lungo button.

Once the coffee maker has been reset, prepare an espresso and a lungo and check that your coffee maker serves less coffee with any kitchen measuring device. It is also important that you record on video with your phone how the coffee comes out for later comparisons.

Cleaning and maintenance problems affect the pressure

The accumulation of limescale and impurities in the Nespresso is why your machine does not serve coffees with sufficient pressure, so you should immediately perform one or more descaling. After descaling, you can re-measure the amount of coffee you get. This can be done by measuring the coffee obtained or recording another video and comparing.

The next step in cleaning and maintenance is to clean the front capsule perforation disk. To clean it, the idea is to use an old toothbrush with clean water and scrub until our brush comes out clean. Occasionally press the lungo button (without capsule) to rinse.

Detail of capsule perforating disk
Detail of capsule perforating disk

It is most likely that after these two cleaning operations, the coffee maker has recovered the correct pressure, but if it has not, go to the next section.

The problem of air inlet in the water circuit of the Nespresso

Although Nespresso capsule coffee makers are not very complicated and do not have water pipes or valves, some can give us headaches. Every time there is a valve-pipe connection, there will be an O-ring that will tend to break over time.

If any of the O-rings breaks or deforms, air can enter the water circuit, affecting the final pressure obtained in the preparation of the coffee. To check that all is well, you should disassemble the coffee maker and prepare some coffees without the casing to closely observe if air enters the circuit.

Normally, when an O-ring is damaged, there will also be a loss of water in that place, so you should be on the lookout for water leaks when there are pressure problems.

Nespresso water pump problems

There are occasions in which descaling and cleaning do not solve the lack of pressure, having to make a deeper investigation focused on the pump. To perform these tasks, you must disassemble the housing of the coffee maker and have physical access to the pump:

Nespresso U without housing, access to the pump
Nespresso U without housing, access to the pump

We must first do a physical inspection, i.e., observe if external damage, rust, discolouration, etc., are visible. If we are not able to see anything, we have two options: Replace the pump with a new one or disassemble the pump, clean it well and replace some O-ring that will have been damaged:

  • A new pump costs about 20 euros on Amazon: write down the characteristics of this one and buy one just like it. It would help if you also bought the metal clips you see in the picture above unless you bend them to remove the pump and then put them back in position. To remove these clips, you should cut them off, in theory.
  • If you are handy, you can try to disassemble it, check its parts, and clean them. Be very careful not to lose any parts and to assemble them correctly after maintenance:
Disassembling a vibratory water pump
Disassembling a vibratory water pump