When selecting a water filter for your coffee machine, three key areas of filter performance should be taken into consideration:
- Sediment reduction - removal of algal spores as well as small particles of dirt, sand and rust will protect the flow path of your machine. It will also prevent the boiler from accumulating sediment which can form a "sludge" acting as a catalyst for scale development.
- Chemical reduction - reduction of chemicals such as chlorine which will negatively affect the taste of espresso
- Total hardness (TH) reduction - this refers to the presence of Magnesium and Calcium salts in the water. Some of these salts can precipitate to form scale. This scale coats boiler surfaces, elements, valves, solenoids, gicleurs and water flow paths. Scale buildup can adversely affect water temperature, pressure, steam performance, water flow rate and taste.
Whilst scale can be removed by chemically descaling the machine, minimising the accumulation of scale with the use of appropriate filtration will dramatically slow the rate of accumulation. Descaling requires the use of acid and this acid will ultimately degrade the thin copper tubing used to link machine components. We do not recommend routine descaling, rather the use of appropriate filtration.
Whilst most filters adequately achieve the reduction of sediments and chemicals quite successfully, scale reduction is a little more complex. Please note that a drinking water filter as recommended by a plumber or retail store is unlikely to be a softening filter - i.e. it will not remove scale. The use of a softening medium in a water filter can achieve a reduction of scale-causing compounds of up to 90%.
How water softening works
Water softening is frequently achieved with the use of an ion exchange resin. This process involves the exchange of scale-causing Calcium and Magnesium for Sodium. Whilst some Calcium and Sodium compounds are insoluble and deposit as scale, Sodium compounds are generally soluble and pass harmlessly through the espresso machine.
Total dissolved solids (TDS)
Total dissolved solids is a measure of all dissolved minerals in the water. A reading of over 300 parts per million (ppm) would suggest that a more complex filtration solution may be required to protect your machine.
In general, Reverse Osmosis (RO) systems are not recommended for use with home espresso machines unless a remineralising medium is in place as well. RO systems produce water without ionic content - the result is that the machine may not fill or may overfill, as espresso machines rely on water conductivity to sense the presence of water.
How do I find out my TH and TDS?
Talk Coffee has testing equipment to test for TH, TDS and chlorine. Bring a water sample with you in a drinking water bottle and we can run a quick test for you. Comprehensive tests can be obtained for a small charge at places such as swimming pool chemical stores and aquariums. Your local water authority will also be able to provide general information.
Note that water quality varies seasonally, so do ask for upper and lower levels. Our experience is that water quality can vary dramatically from house to house within one street, so the best results will be obtained with a test of your own water.
My water is not that hard. Do I still need a softening filter?
The heating and cooling of water in espresso machines is the primary reason for scale formation. Home-use machines are often switched on and off more than machines in commercial environments - this makes scale formation more likely, even in areas where the water is considered to be soft. The smaller boilers of home machines can further accentuate this.
Please note that the level of scale reduction can and does vary according to the type of resin used in the filter and the local hardness of the water source. We recommend specific filter products based on local water conditions - come in and talk to us about what's right for your area and machine.