Why does water matter so much for an espresso machine?
Water does two jobs at once. In the cup, it extracts flavour and aroma from the coffee, so you can taste its composition in every espresso. In the machine, it flows through the boilers, groups, valves and steam wands, so it determines whether these parts run for a long time without problems.
The boilers in La Marzocco machines are made of AISI 316L stainless steel and TIG-welded by hand. That's a solid foundation, but even the best boiler needs the right water. That's why we treat water as part of the machine installation, not an extra.
Hard or soft water: what harms an espresso machine?
Hard water contains a lot of minerals, which are deposited as scale when heated. Scale builds up in the boilers, valves and on the heating elements, narrows the pipes and reduces flow. The result is slower operation, weaker steam and more downtime for service.
Water that is too soft or aggressive is the other extreme. It can encourage corrosion of metal parts and makes espresso taste flat. So the goal isn't the softest water possible, but water that is matched: soft enough not to leave scale, and balanced enough for the coffee to taste good and the parts to stay safe.
How do you check the water in your venue?
At installation, we test the water in your venue and choose a filter based on the result. Mains water in the same town can differ from street to street and even change over the year, so don't rely on figures for the whole city.
Some machines help you keep an eye on the water day to day. The Linea PB, Linea PB X, KB90, GB5 S and GB5 X have a sensor that measures the conductivity and hardness of the water entering the machine. This way you'll notice a change in the water or a worn-out filter sooner.
Want to know which filter suits the water in your venue? We'll check during a consultation.
How do you choose a filter for an espresso machine?
We choose the filter based on the water test result and the volume in your venue. The more coffees and the more water used for steam, the larger the cartridge capacity that makes sense. We install the filter under the counter, before the machine, with access to change the cartridge without dismantling the cabinetry. We cover space for the filter in our guide Preparing your venue for an espresso machine.
Our advice: don't choose a filter by guesswork, and don't move a cartridge from your old venue to a new one without a water test. What worked in one district may not be enough in another.
How often should the filter cartridge be changed?
A filter cartridge has limited capacity. Change it according to water usage and the filter instructions, not only once scale appears. In practice, high-volume venues need to change it more often than a small café.
- Write the installation date and planned change date on a sticker by the filter.
- Add the cartridge change to your service plan or the team calendar.
- After changing it, flush the cartridge according to the filter instructions before the water reaches the machine.
- If the espresso taste or the water sensor reading changes, check the filter earlier.
How can you tell something is wrong with the water?
| What you see | What it may mean | What we do |
|---|---|---|
| white deposits on the steam wands, in the drip tray and on the baskets | hard water, an exhausted filter cartridge | we test the water and check the cartridge change date |
| flat, sour or bitter espresso despite a good grind | the water composition has changed or the filter has stopped working | water test, comparison with the result at installation |
| weaker water flow from the groups or hot water tap | scale in the system or a blocked filter | cartridge change, service |
| changed water sensor reading (Linea PB, PB X, KB90, GB5) | different hardness or conductivity of the incoming water | checking the filter and changing the cartridge if needed |
Daily cleaning won't make up for poor water, but it helps you spot a problem early. You'll find a schedule for your team in our guide Cleaning an espresso machine and backflush.
Water, steam and milk drinks
Water doesn't only go into espresso. The steam boiler runs at high temperature all day, so it's the first to scale up with hard water. The symptoms are weaker, wetter steam and longer milk texturing. In a venue that sells a lot of cappuccino and latte, good filtration translates directly into speed at peak time.
Hot water from the tap for americano and tea comes from the same system. If its taste or smell changes, that's a sign to check the filter before the change affects the espresso.
New venue or new machine: where to start?
- Plan space for the filter under the counter and a shut-off valve before it.
- Ask for a water test before or during installation.
- Choose a filter based on the test result and the volume in your venue.
- Set a cartridge change date and add it to your service plan.
- If you move venue or change water supplier, test the water again.
Can you use bottled water or water from a filter jug?
We don't recommend it in a venue. A commercial espresso machine is plumbed permanently into the water supply, and jugs or bottles can't guarantee a consistent composition and quantity of water at high volume. It's better to choose the right filter on the supply once and keep up with cartridge changes.
frequently asked questions
What is the best water for a café espresso machine?
Water matched to the machine: soft enough not to leave scale, and balanced enough for the coffee to taste good and the parts not to corrode. At installation, we test the water in your venue and choose a filter.
Is a water filter necessary for an espresso machine?
In practice, yes. Mains water is rarely suitable for an espresso machine straight away. A filter protects the boiler and valves from scale and helps keep the espresso taste consistent.
How often should the filter cartridge be changed?
According to water usage and the filter instructions. More often in high-volume venues. Note the change date and check the filter earlier if the coffee starts to taste different.
Which La Marzocco machines have a water sensor?
Linea PB, Linea PB X, KB90, GB5 S and GB5 X. The sensor measures the conductivity and hardness of the water entering the machine.
What if there's already scale in the machine?
Don't descale the machine with home remedies. Report it to our service team: we'll assess the machine, choose a new filter and schedule a service.
read also
- Linea Mini or GS3? Which one for your home?
- Which espresso machine for an office? Does a traditional one make sense?
- Linea Micra or Linea Mini? Which one for your home?
- Grind-by-Sync: how La Marzocco controls a Mahlkönig grinder
- How to make milk drinks faster in a café
- Espresso machine for a roastery or showroom: how to show off your coffee
- 10 mistakes when buying a café espresso machine (and how to avoid them)
- Espresso machine for a bakery or patisserie: selling coffee alongside your bakes
- Is a more expensive café espresso machine worth it?
- New espresso machine in your café: a barista training plan for the first month
- Espresso grinder for a café: on-demand or doser, and how many you need
- ABR drip tray scales or AV dosing? When the extra cost pays off
- Espresso machine service: what it covers, how often, and when to call a technician
- Café espresso machine leasing: lease, rent or buy?
- La Marzocco in Warsaw: Tekla, Doza and Wandal
- Specialty café: which espresso machine to choose? What a specialty café needs
- Opening a café? An equipment plan, step by step
- Dual boiler, saturated group, independent boilers: what they change in the cup
- When to replace your café espresso machine? 5 signs
- Espresso machine cleaning and backflush: a schedule for your team
- Espresso machine for a restaurant or hotel: what to look for
- Which espresso machine for a café? A guide to La Marzocco machines
- Linea Classic S, Linea PB, KB90 or Strada? A comparison
- AV, ABR, EE, MP: what La Marzocco machine versions mean
- Preparing your venue for an espresso machine: power, water, drain
- How many groups does your venue need?