Go with the flow: why your coffee machine needs the right water

25 November 2022 by
Go with the flow: why your coffee machine needs the right water

Coffee machines demand the right type of water: acidity causes corrosion and if it's too hard it creates limescale. Ian Boughton discovers how to get your water just right

"Water is going to become a more critical commodity than oil. It is going to be very important for you to better understand and respect your water."

The remark comes from Louie Salvoni of Espresso Service, just one of many beverage specialists to be exasperated about how little attention is given to water by the trade that uses it to brew drinks.

Water is a known problem in hospitality. It affects the taste of drinks, it damages brewing equipment, and the solution is far more challenging than simply fitting a filter. Who really understands the water problem? It has been suggested, with some mischief, that the real experts are our baristas, the ones who brew hundreds of coffees every day and who are quite literally in touch with the quality of the water they use. Indeed, it was James Hoffmann, the first Briton to become world barista champion, who once notably complained that "London water wants to kill coffee machines".

"I stand by that," he says. "London's water is a massive headache, from both an equipment and taste perspective. The best solutions are seen as expensive, when in fact the cost of proper water filtration, while seemingly high, is far lower than the cost of a descaling a commercial espresso machine."

The most notable scientific analysis of water in the hospitality sector is also by a champion barista, Maxwell Colonna-Dashwood of Bath. With chemist Christopher Hendon, he wrote the book Water For Coffee, which showed baristas and chefs how to understand the water they work with. His work came from the practical experience of being puzzled that a certain coffee which tasted super at a roastery then completely changed its character when brewed at his own café. His analysis is highly scientific, and yet he argues that any food and beverage manager can put the principles across to staff in an entertaining way that may transform the drinks they serve.

"A tasting experience is easy to do, and it never fails to surprise people. The big surprise comes when you brew the same coffee with different waters, and your staff are sure they are tasting different coffees! To try it simply, brew your house coffee with Evian, which is very high hardness, and Volvic, which is relatively soft, and ask your staff to compare them.

"Another example is to add minerals to a drink to mimic water hardness – brew a coffee as normal and then add a tiny pinch of bicarbonate of soda. You will notice the acidity of the coffee gets wiped out."

Maxwell Colonna Dashwood and Christopher Hendon
Maxwell Colonna Dashwood and Christopher Hendon

Supplier bias

This kind of demonstration might not be offered by a water-filter sales person. So in the eyes of baristas, do suppliers really know what they're talking about?

"Filter sellers have always been more knowledgeable than the operators they supply to," remarks Colonna-Dashwood generously, "but the drawbacks are the bias each company has to its own solutions. The engineers I meet from these different companies do typically have a decent understanding of water and filtration, though their messaging may be over-simplistic. This is not because of a knowledge deficit, but more a desire to simplify something complex, and it's problematic when that messaging can become misleading."

Many filter companies have treated his research with respect. "It remains a mystery to me why so many water filter suppliers still promote the idea that you only have ‘hard' water or ‘soft' water," agrees Nigel Pask, sales manager at Pentair. "Historically, we have grown up to believe that water is either ‘soft' and requires minimal treatment, or is ‘hard' and that limescale deposits become the issue. As times have changed, there has been a greater understanding of the impact of water quality on the taste of coffee, but we are still only at the start of the journey in teaching about the impact water has on equipment.

The cost of proper water filtration, while seemingly high, is far lower than the cost of a descaling a commercial espresso machine

"Many modern machines are much more susceptible to corrosion, and treating the water for limescale can potentially accelerate corrosion issues. Older coffee equipment was often made from copper and the issue then was limescale, and a low pH, acidic water would dissolve the soft metals. Stainless steel still has the problems with scale, but is ‘stainless steel', not ‘corrosion-less steel' – it doesn't like chloride or sulphate salts, especially at high temperatures and low pH.

"So there really is a fine balance in achieving your beverage quality, your equipment protection and your cost of ownership.

"The good news is that companies such as Pentair are reacting, understanding the local water conditions and translating these into a package that meets the operator's needs."

In an attempt to simplify the understanding of water, a coffee trade association did try to establish the ‘ideal' water for brewing, and came up with a fairly vague guidance of a topmost level of 300ppm of total dissolved solids. However, this ‘parts per million' reading actually varies widely around the UK – it can be 50ppm in western rural areas, and over 400 on the east coast.

Therefore, as water quality around the UK varies so much, no single filter will be right for everywhere – and in addition, say the suppliers, the aim of a filter should not to be to remove all solids, but to remove the right ones.

"It's really important to strike the right balance of water content," says Sam Scoles, sector manager at Brita. "The ‘hardness' of the water running through a coffee machine will affect the taste of the final serve – the ‘harder' the water is, the less sour the coffee will be. If the water is too soft, you'll be left with an unbalanced drink that's extremely sour.

"So, the aim should never be to remove all elements, but instead to strike the right balance so that the taste of the coffee can shine, and a water filter can do this by adjusting the amount of hydrogen carbonate present."

We know that water that is too hard will create limescale, and too pure a water will corrode. Both mean expensive repairs

Forgotten filters

Whatever filter may be fitted, a big secret is knowing when to change it. Changing one too rarely affects water quality, the brew taste, and endangers machine safety; changing too frequently is simply a waste of money. Many filters in catering premises simply get forgotten about.

It is again the coffee trade which has come up with an answer – Louie Salvoni of Espresso Service has devised the Hydracs system.

"We understand this because we are the people who know both coffee and machines. We know about the need for an amount of mineral content, because pure water is no good for coffee or machines – it is bad for taste. For machines, we know that water that is too hard will create limescale, and too pure a water will corrode. Both mean expensive repairs.

"We have been frustrated at the lack of understanding of this in hospitality, where the norm has been ‘put in a filter and change it once a year'. That has been just guesswork, but now Hydracs determines ‘when'. It saves the user from paying too much for too-frequent filter changes, and protects their equipment from too few filter changes. To create it, we worked with boffins from the oil industry."

The Hydracs system does two jobs – it measures both the flow of water and the total dissolved solubles, effectively monitoring the job that the filter is doing. When the filter is exhausted, the system sends an alert; if the quality of the water changes, perhaps because water has come in from a different area, the operator is alerted.

Hydracs studied the experience of a contract caterer with 750 coffee machines across its estate. Around half were on maintenance contracts, while the others only had their filters changed if the onsite staff remembered. Hydracs analysed the filter changes of machines, noting both when filters became exhausted after a short period of time, and when machines were still being used long after their filters had ceased to work properly. They analysed also the number of machines which did have filters changed, and yet still had to go into a workshop for a descale. In all, the operator realised that they were paying £100,000 a year just for descaling work.

"A lot of smaller operators have come to understand the implications of this," remarks Salvoni. "When they realise that a descale can easily cost £1,000, they tend to see the point."

Belu brands itself for hotels

Filtered water by the glass, to be drunk at the table, is something water brands have long recommended. But Belu allows for its water to be poured from a branded bar tap.

As with many others, Belu says it does not aim for an entirely ‘pure' water for reasons of taste: "Quite a lot is removed, but not everything, and in terms of a taste profile, we describe the result as ‘crisp'," says the brand's Georgie Murray.

Belu says the trade has approved of the brand's support for Water Aid. The Pig hotel group, having noted that bottled mineral water sales were declining and that more customers were asking for tap water, created a ‘Positive Profits' project, charging each table £1.50 for unlimited water and reinvesting half of the revenue into Belu's fundraising.

The Inhabit boutique hotel has placed a Belu filtration system on every floor. Guests receive a filled carafe on arrival, and are invited to help themselves to refills during their stay.




Espresso Service/Hydracshydracs.com


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