Water is one of those strange things that some kitchens can easily ignore, confident in the quality coming out of their tap; while others are cursed to obsess over and spend to improve theirs. Wherever you wind up on that spectrum, it always pays to spend a little effort and attention on your water. As an ingredient, it is in every bit of food and drink you serve, after all. If you get the right water flowing through your espresso machine, every shot you pull can be rich in color and taste, with a perfect crema on top. Haphazardly dump any old water into your steamer though, and it may just eat your equipment from the inside out.
The Bad Actors
Problems with your water broadly fall into three categories: dissolved minerals, suspended sediment, and added chemicals.
There are all kinds of minerals that can dissolve in water and impact the taste. While they may add an unpleasant flavor, the bulk of these minerals are not harmful for human consumption. Notable exceptions to this include lead and mercury, which can sometimes be found in water supplied adjacent to heavy industrial activity where waste was not properly isolated from the environment.
In terms of your equipment, the minerals that filter manufacturers look to remove are magnesium, phosphates, iron, silicates, and calcium. The presence of these and other minerals is measured in Grains Per Gallon (GGP). A single Grain of water hardness is 17.1 parts per million of dissolved minerals. If water has more than 7 Grains per Gallon, it is said to be hard, while anything above 10.5 Grains is very hard. In layman’s terms, 7 GGP would be roughly one pound of dissolved minerals in 1,000 gallons of water.
Sediment, meanwhile, is large particles that don’t dissolve in water, but do suspend themselves in it and get carried into the supply. This includes materials like sand, or bits of organic matter such as decaying plants. The presence of sediments is measured in Turbidity, and while there are complex ways to quantify turbidity based on light refraction, it is easiest to think of it as the “cloudiness” in your water. The cloudier your water, the higher its turbidity, and the higher the amount of sediment in it.
Finally, the dissolved chemicals mentioned earlier usually come in the form of chlorides, often as a byproduct of the sterilization process your city performs on its water supply. Their presence in your water is not harmful to your health, but as we’ll discuss below, they can dramatically impact the flavor of your beverages and the operation of your equipment.
What Could Go Wrong?
The most immediate problem you may notice with hard water (or water with chlorides in it) is a bad taste. Perhaps you’ve traveled somewhere with hard water and noticed a sort of iron or sulfur flavor to the water – that’s hard water you’re dealing with. In addition to this odd flavor, hard water can result in flat soda from dispensers, cloudy coffee and tea, and espresso with no crema (foam) on top.
When water isn’t treated for this excess minerality, the next problem you’re likely to face is scale build-up. Scale is the term for when these minerals precipitate out of the water and deposit on nearby surfaces. You’ve probably seen this in your own bathroom in the form of soap scum. When it happens in pipes (inside your walls or inside your equipment) the build-up can choke your water flow, reducing water pressure and the available supply. When it happens in boilers, such as for combi ovens or steamers, the scale forms specifically in the location where the heating elements are, creating an insulative barrier that reduces the energy efficiency of your devices. Left untreated, this will eventually burn out your heating elements. Calcium, in particular, bonds with carbon to produce an especially tenacious and hard to remove scale called Lime.
Chlorides can also be quite damaging to heated equipment. When temperatures rise above 212 degrees they can quickly bond with sodium to form a hydrochloric acid that corrodes the metal in boilers. This corrosion is known as “pitting”, and if you’ve ever seen exposed metal near the sea being eaten away in the salty air, then you’ve seen pitting in action.
Is There a Cure?
So what sort of treatment options exist? Solutions can broadly be grouped into chemical or filtration. The most common chemical treatment that many might be familiar with from their homes is water softening. In water softening, sodium ions are exchanged for the mineral ions in the water, taking their place. This adds some sodium to the water, but usually in low enough concentrations that you wouldn’t taste a salty flavor. Water softening excels in applications such as dishwashing, where water temps usually hover around 180 degrees and excessive hardness would impact the efficacy of the detergents. However, it is not recommended for beverage or cooking applications, as it causes over-extraction in teas and coffees, leading to bitterness and cloudiness. In cooking, water is usually raised to above 212 degrees, where the sodium from water softening would combine with chlorides and cause pitting.
Various other proprietary chemicals get used by filter manufacturers to reduce hardness, and while it would be impossible to write about them all, they do function in a similar fashion: these chemicals are added to the water supply, where they serve as nucleation point for dissolved minerals. That is, instead of precipitating onto the boiler where the heating element is and forming scale, the minerals precipitate onto these larger chemical molecules, which resist settling on the boiler and get flushed out of the system when the boiler is drained.
In standard filtration, water with a high turbidity should begin treatment by going through a sediment pre-filter. These pre-filters pass the water through a physical medium with pores too small to allow sediment past the filter. This process is a lot like your coffee filters at home, albeit with somewhat more sophisticated materials. A sediment pre-filter is not strictly necessary, just to be clear, but if you have high-turbidity water and no pre-filter, you will burn through your carbon filter cartridges at a much faster rate.
Carbon filters typically consist of spun fibers coated in activated charcoal. Activated charcoal is charcoal that’s been treated with oxygen to create lots of tiny pores on its surface, increasing the surface area exposed to the water. As water passes in and out of the absorbent fibers, the charcoal has a chance to absorb impurities, such as the commonly found minerals we’ve discussed, as well as chlorides. High-capacity water filters will often have 2, 3, or 4 carbon filters working together, to increase the overall rate of water flow. If you notice that the water pressure coming through your filter has lessened, slowing the overall flow, this likely means that your filters are expended and should be replaced.
Last, but not least, are Reverse Osmosis systems. These systems use pressure to push water through a semi-permeable membrane that allows water to pass through, but rejects minerals, chlorides, sediment, sodium, and most pathogens. R.O. systems operate slowly, so most are continuously filtering water into a reservoir tank for when it’s needed.
These systems produce water so pure that in some applications it becomes necessary to add a small amount of minerality back in. For example, minerality is usually added back into the R.O. system’s product before use in steamers and combi ovens, otherwise boilers can be damaged. In coffee and espresso applications, small amounts of magnesium should be present in the water to improve extraction from the coffee grinds and for flavor. When R.O. is used in coffee or espresso applications, the manufacturer will often supply a cartridge to returned measured doses of magnesium to the water before it goes to the brewer.
Flow Gently, Sweet Afton…
So how does an intelligent designer determine the needs of their kitchen? Your best bet is to partner with your selected filter manufacturer, and to obtain their recommendation. Most large municipalities publish water quality reports annually, but if you lack an expertise in environmental science, it can be easy to become dazed by all the information presented. Most of the larger filter manufacturers have experience with wide swaths of water tables throughout the country and can help with preliminary specifications, but it is always a good practice to obtain a local water supply sample and order a test be done to verify their filter recommendations.
If you do partner with a filter supplier for model recommendations, consider sharing specification sheets with them for any ice machines and any heated equipment such as combi ovens, steamers, and hot water boilers. Manufacturers often provide their water quality requirements in the small print, and as water mismanagement is a growing source of warranty disputes, they are getting very particular about their requirements. A few dollars for a water sample kit and some leg work in the design stage can prevent some tremendous headaches during the lifespan of your water-using equipment.
By: Kevin Banas
Project Manager | Chicago