Why use a coffee machine water filter?

First of all, the most important reason, preventative maintenance. The majority of coffee machine breakdowns are directly related to scale. A coffee machine water filter will protect equipment from this risk, when used correctly. For best results combine this with a water hardness test kit.

Estimated reading time: 15 minutes

Secondly, to prevent the passing of unwanted particles, into machines. The most commonly found particles in water are rust and silica.

Heavy metals such as copper and lead as well as organic pollutants and pesticides must be filtered. Chlorine in water can make a good quality coffee taste awful.

Put simply all of the above will degrade the taste and the aroma of coffee if left unfiltered. Moreover the appearance of coffee and tea is completely different when made with filtered water, it will be darker and if left a scum cloud will appear on the top.

Filtered water accelerates the extraction of flavour in coffee. This is subjective, however it is obvious to everyone that filtered water always makes a better coffee. This is even more so when the filtration enables the quality of water to fall within a certain cross section of variables.

How calcium enters rain water

Rain collects carbon dioxide whilst falling through the air. Carbon dioxide then sieves through the ground collecting solid lime scale (CAC03). The scale is dissolved by the Carbon Dioxide and retained within the rain water mixture.

The result is CA2+ (Calcium) and 2HCO3 (hydrogen carbonate), a deadly combination so far as coffee machines are concerned.

When disaster strikes

The nasties contained within tap water mostly fall under the description of TDS, aka temporary dissolvable solids. TDS is also referred to as carbonate hardness. The levels of TDS can be detected using the water hardness test kit.

Temporary dissolvable solids dissolve when water temperature reaches 60 degrees and above. When this happens all hell breaks loose and the destruction of expensive machinery begins.

The breakup or separation of hydrogen carbonate into carbonate and carbon dioxide occurs at a temperature of 60 degrees and above. The carbon dioxide is burnt off leaving calcium and carbonate to team up creating a near insoluble danger. It’s lime scale precipitation time.

How a coffee machine water filter works

All good coffee machine water filters work predominantly using a process named Ion Exchange.  Calcium is a component of lime, hence the phrase lime scale. Calcium or CA2+ is drawn to the Ion exchanger whereby Hydrogen is released.

In simple terms the Calcium is exchanged with the Hydrogen and the calcium is cancelled out. In a Brita filter the Ion exchange happens with beads. The beads have a limited life span. When filtering capacity is quoted as an input of litres or one year whichever is sooner, this is why.

Once the beads have been compromised they will only last for a maximum of one year. This is regardless of how much or little water is put through. Filters are a food safe product, the 12 month maximum is therefore very important.

The hydrogen Ion exchange system is only applicable to Brita filters of the type Purity C. At Happy Donkey this is the system used the most.

The Purity C Brita filters use either a standard 30% bypass head, or an adjustable 0 – 70% head. The purity C filter cartridge contains both non Ion exchange resin and ion exchange resin. The level at which the bypass is set to, determines the percentage of water going through the non Ion exchange resin beads only.

In simple terms set the head to 70% to allow only 30% of the water through the Ion exchange part of the filter. The 70% remaining water will only be filtered by the non Ion exchange beads (activated carbon). The two meet at the other end and flow as one. So beautiful.

Ion exchange resin

Filters and works like a magnet attacking scale and heavy metals examples being copper, lead and Aluminium. Ion exchange helps to promote great tasting coffee with a good aroma. Protects coffee making equipment from lime scale and magnesium..

In the Purity C filter this is the 2nd stage of filtration, the first being the filtering of large particles via a particle filtration fleece.

Activated carbon in a coffee machine water filter.

A black particle bead that filters like a sponge would. Made from coconut shells. Excellent at absorbing chlorine, pesticides, odour and organic particles. Reduces carbonate hardness levels. Carbon is a proven bacteria killer. This is the 3rd stage of filtration in the Purity C filter.

The final stage of filtration involves holding back the finest particles found in tap water.

The water life cycle.

Water is not born bad. Rain water is slightly acidic by nature. It is the journey of the water, once earth bound which dictates the held qualities and attributes.

Water settled and worked through a lake will have a completely different profile to that which has settled and worked through porous rock. Water is a product of the environment in which it travels through, much like people.

Supplied Water in the uk in modern times does not necessarily originate locally.

The knock on effect of this is the practice of pumping water up and down the country as required. There is no longer such a thing as a permanent hard or soft water area any more.

The focus therefore should not be on the area in which we are working but the water which we receive from the tap in that area.

Testing water for Carbonate hardness using the water hardness test kit.

Testing for carbonate hardness is a great place to start when figuring out what filtration is required from a coffee machine water filter. Using a Brita adjustable bypass ratio head it is possible to get really accurate filtering of the water used to make the coffee with.

Shown below is the measuring guide using the Brita carbonate hardness testing kit.  Use the result of the kit and the chart below it to work out what filtration is required.

Instructions for using the Brita water testing kit.

If uncertain of the colour add one more drop, if the yellow does not get stronger as a colour then use the previous count, ignoring the last drop. Most noteworthy is if warm or hot water is used in the test a false result will be given.

Using the water hardness test kit result.

Presuming the result of the test was a score of 4 or above. The charts indicate various sizes of Brita Purity C cartridge. How much effective capacity of filtration they will give and level of bypass to use.

In the first chart a recommended bypass is shown in relation to the score. This makes the presumption a 0-70% variable bypass head is being used. This chart is for espresso, coffee and vending machines.

For example if the carbonate hardness test score is 8 then a 50% bypass setting on the adjustable head is suggested. Looking across the column we see a Purity C500 cartridge will effectively filtrate 10094 Litres of tap water.

A litre is 1000 ml, a double shot of espresso is 60ml. Therefore it is usual to expect around 16 double shots of espresso to every litre. We have 10,000 Litres, so we should get approximately 16,000 double shots from that filter on a 50% bypass setting. Or one years use whichever comes soonest.

The Brita Flow meter is worth a purchase, this will record exactly how many Litres have passed through the machine.

Most noteworthy is the ability to remember that coffee machine are not only used for espresso shots. All water run through the espresso coffee machine should be accounted for and added to the used volume figure.

To be safe take away 20% of the volume to start with then divide the remaining figure by 60. If all this does your head in, mail the result in to Happy Donkey and it will be done for you provided the water testing kit was purchased at Happy Donkey of course.

Espresso, Coffee and vending machines. Brita Purity C using 0-70% head. Bypass showing Litres based on Brita filter cartridge size.

Carbonate Hardness score	Recommended by-pass setting	Purity C50 capacity in Litres	Purity C150 capacity in Litres	Purity C300 capacity in Litres	Purity C500 capacity in Litres	Purity C110 capacity in Litres
4	70%	1900	4766	7917	13458	22760
7	60%	1821	4569	7589	12902	21819
8	50%	1425	3574	5938	10094	17070
9	40%	1267	3177	5278	8972	15174
10	40%	960	2408	4000	6800	11500
11	30%	873	2189	3636	6182	10455
12	30%	693	1738	2887	4908	8300
13	30%	640	1604	2665	4530	7661
14	30%	594	1490	2474	4207	7114
15	30%	554	1390	2310	3926	6640
16	30%	520	1303	2165	3681	6225
17	30%	489	1227	2038	3464	5859
18	20%	462	1159	1925	3272	5533
19	20%	387	970	1612	2740	4634
20	20%	368	922	1531	2603	4402
21	20%	350	878	1458	2479	4193
22	20%	334	838	1392	2366	4002
23	20%	320	802	1332	2264	3828
24	20%	306	768	1276	2169	3669
25	20%	294	737	1225	2083	3522
26	20%	283	709	1178	2002	3386
27	20%	272	683	1134	1928	3261
28	20%	263	658	1094	1859	3145
29	20%	253	636	1056	1795	3036
30	20%	245	615	1021	1735	2935
31	20%	237	595	988	1679	2840
32	20%	230	576	957	1627	2751
33	20%	223	559	928	1578	2668
34	20%	216	542	901	1531	2590
35	20%	210	527	875	1488	2516

More charts

Next is the 30% bypass chart, this also applies to espresso coffee machines and presumes the fixed 30% bypass head will be used. The same principle of measurement should be used as discussed above. Again use in conjunction with the water hardness test kit.

Brita Purity C using 30% bypass showing litres based on Brita filter cartridge size.

Carbonate Hardness score	Recommended by-pass setting	Purity C50 Capacity in Litres	Purity C150 Capacity in Litres	Purity C300 Capacity in Litres	Purity C500 Capacity in Litres	Purity C1100 Capacity in Litres
4-6	30%	1386	3476	5774	9815	16600
7	30%	1188	2979	4949	8413	14228
8	30%	1039	2607	4330	7362	12450
9	30%	924	2317	3849	6544	11066
10	30%	831	2086	3464	5889	9960
11	30%	756	1896	3149	5354	9054
12	30%	693	1738	2887	4908	8300
13	30%	640	1604	2665	4530	7661
14	30%	594	1490	2474	4207	7114
15	30%	554	1390	2310	3926	6640
16	30%	520	1303	2165	3681	6225
17	30%	489	1227	2038	3464	5859
18	30%	462	1159	1925	3272	5533
19	30%	438	1098	1823	3100	5242
20	30%	416	1043	1732	2945	4980
21	30%	396	993	1650	2804	4743
22	30%	378	948	1575	2677	4527
23	30%	361	907	1506	2561	4330
24	30%	346	869	1443	2454	4150
25	30%	333	834	1386	2356	3984
26	30%	320	802	1332	2265	3831
27	30%	308	772	1283	2181	3689
28	30%	297	745	1237	2103	3557
29	30%	287	719	1195	2031	3434
30	30%	277	695	1555	1963	3320
31	30%	268	673	1118	1900	3213
32	30%	260	652	1083	1840	3112
33	30%	252	632	1050	1785	3018
34	30%	245	613	1019	1732	3929
35	30%	238	596	990	1683	2846

Going hardcore with the filtration this chart uses figures relating to a 0% bypass.  This is not usually a good idea, but if the urge is there here is the data.

Brita Purity C using 0% bypass showing litres based on Brita filter cartridge size.

Carbonate Hardness Score	Recommended by-pass setting	Purity C50 Capacity in Litres	Purity C150 Capacity in Litres	Purity C300 Capacity in Litres	Purity C500 Capacity in Litres	Purity 1100 Capacity in Litres
4-6	0%	1000	2508	4167	7083	11979
7	0%	857	2150	3571	6071	10268
8	0%	750	1881	3125	5313	8984
9	0%	667	1672	2778	4722	7986
10	0%	600	1505	2500	4250	7188
11	0%	545	1368	2273	3864	6534
12	0%	500	1254	2083	3542	5990
13	0%	462	1518	1923	3269	5529
14	0%	429	1075	1786	3036	5134
15	0%	400	1003	1667	2833	4792
16	0%	375	941	1563	2656	4492
17	0%	353	885	1471	2500	4228
18	0%	333	836	1389	2361	3993
19	0%	316	792	1316	2237	3783
20	0%	300	753	1250	2125	3594
21	0%	286	717	1190	2024	3423
22	0%	273	684	1136	1932	3267
23	0%	261	654	1087	1848	3125
24	0%	250	627	1042	1771	2995
25	0%	240	602	1000	1700	2875
26	0%	231	579	962	1635	2764
27	0%	222	557	926	1574	2662
28	0%	214	538	893	1518	2567
29	0%	207	519	862	1466	2478
30	0%	200	502	833	1417	2396
31	0%	194	485	806	1371	2319
32	0%	188	470	781	1328	2246
33	0%	182	456	758	1288	2178
34	0%	176	443	735	1250	2114

Last but not least a chart for those using the Purity C on a combination or conventional oven. Note well this chart relates specifically to steam filter heads an cartridges which is different to a coffee machine water filter.

Combi and conventional oven filtration using Brita Purity C with 0-70% head, bypass showing litres based on Brita filter cartridge size.

Carbonate Hardness score	Recommended by-pass setting	Purity C50 capacity in Litres	Purity C150 capacity in Litres	Purity C300 capacity in Litres	Purity C500 capacity in Litres	Purity C110 capacity in Litres
4-6	10%	1100	2759	4583	7792	13177
7	10%	943	2365	3929	6679	11295
8	10%	825	2069	3438	5844	9883
9	10%	733	1839	3056	5194	8785
10	10%	660	1656	2750	4675	7906
11	10%	600	1505	2500	4250	7188
12	10%	550	1380	2292	3896	6589
13	10%	508	1273	2115	3596	6082
14	10%	471	1183	1964	3339	5647
15	10%	440	1104	1833	3117	5271
16	10%	413	1035	1719	2922	4941
17	10%	388	974	1618	2750	4651
18	10%	367	920	1528	2597	4392
19	10%	347	871	1447	2461	4161
20	10%	330	828	1375	2338	3953
21	10%	314	788	1310	2226	3765
22	10%	300	753	1250	2125	3594
23	10%	287	720	1196	2033	3438
24	10%	275	690	1146	1948	3294
25	10%	264	662	1100	1870	3163
26	10%	254	637	1058	1798	3041
27	10%	244	613	1019	1731	2928
28	10%	236	591	982	1670	2824
29	10%	228	571	948	1612	2726
30	10%	220	552	917	1558	2635
31	10%	213	534	887	1508	2550
32	10%	206	517	859	1461	2471
33	10%	200	502	833	1417	2396
34	10%	194	487	809	1375	2325
35	10%	189	473	786	1336	2259

Which coffee machine water filter?

Generalising is a dangerous thing to do with water filters for coffee machines. Most noteworthy is the requirement to test the water and use the charts above.

If time is of the essence and a filter needs to be ordered before testing can be done, then as a ballpark figure note the following:

1 group machine – Purity C300

2 group machine – Purity C500

3 group machine – Purity C1100

1 or 2 group machine in a very soft water area – Purity C Fresh

Please do not buy a filter and then not bother to test the water. This can lead to problems.

When water bites back

Water becomes active when stripped of all  mineral content. What this means is the water actively seeks to take on minerals and metals, strange but true.

Over time active water can eat holes in copper boilers and pipe destroying a coffee machines internals. This will be true of water which is over filtered or even run through a reverse osmosis system.

Selling a coffee made with reverse osmosis water is illegal in the UK. This is for health reasons. Water carries nutrition which helps the human body.

This highlights the importance of using a water hardness test kit before a coffee machine water filter is fitted.

Coffee machine Water fIlter for domestic espresso machines.

For machines enabling access to the water intake pipe in the tank, there is the domfilter. A domfilter contains the same Ion exchange and active carbon beads as the commercial machine filters.

Use of bottled spring water such as Highland Spring can reduce the amount of inpurities going into the machine. Spring water certainly does away with Chrlorine and pesticides too.  Most noteworthy is that spring water does contain calcium, so be aware.

Filter jugs can also work well, for best results use the water hardness test kit and combine all three of the above. The battle against scale is never over.

To buy any of the items mentioned in the article buy at Happy Donkey.

Keeping the water supply filtered is important and so is keeping coffee grinders clean why not give this a read: guide to cleaning coffee grinder blades