Seeking input on BWT-jug-filtered water

Water analysis, treatment, and mineral recipes for optimum taste and equipment health.
Sailorman

#1: Post by Sailorman »

Purpose of this post is to seek input on whether my water is a 'weak link' in my espresso preparation assuming I am looking for some appropriate balance between minimizing scale / enhancing taste for a new espresso machine I have on order.
I currently use a jug-based BWT filter to process tap water - as the family seem to appreciate the improved taste relative to tap water the filter only lasts about three weeks before it reaches a 100-jug-refill limit triggering a replacement.
I summarise below what seem to be relevant stats from my local '2019 Drinking Water Analysis' (but in case I have missed out something important I also reference https://www.toronto.ca/wp-content/uploa ... _AODA.pdf the full report).

Input appreciated.

Units Avg
General Chemical and Physical Parameters
Alkalinity mg/L 89.3
Hardness (as CaCO3 -calculated ) mg/L 127
pH 7.5
TOC mg/L 2
Dissolved Solids (calculated) mg/L 210

Inorganic Parameters
Calcium mg/L 35.6
Chloride mg/L 28.3
Magnesium mg/L 9.3

User avatar
homeburrero
Team HB

#2: Post by homeburrero »

This post has gone a long time with no replies.

I neglected responding, partly because I don't know (and can't find) good softening performance data for that BWT jug filter. Also I worry about my comments and opinions causing undue concern and overthinking about water when it may not be a major issue.

But I'll weigh in, and that may tempt more from others who may want to expand or disagree.

To start, I'll say that based on those Toronto water numbers, your water may deposit light scale if not softened. Your calcium (from the linked report) is 31 - 38 ppm, or calcium hardness of about 78 - 95 mg/L CaCO3 equivalent. That, with the 83 - 95 mg/L alkalinity predicts light scale deposits in a 125 ℃ steam boiler. (Your water's Langelier Saturation Index (LSI) at pHeq of 7.4 comes out to about +1.0 )

It also has borderline high chloride of 23 - 51 mg/L (28 mg/L average) . This is a sliver below the 30 mg/L level where La Marzocco often recommends going to an RO system to remove that chloride (conventional filters do not remove chloride). Synesso is more conservative, and recommends that water have chloride numbers below 15 mg/L.

Looking at your current filter, a BWT jug filter, you can expect some softening because of the WAC resin that they use in that filter. But it's not clear how much softening you get out of it. If you replace the filters per recommended intervals you may not get scale deposits, but you'd need to keep an eye out for that and be ready to possibly descale the machine sometime in the future.

The WAC resins normally reduce hardness and alkalinity by an equal amount, and may acidify the water slightly. This all helps reduce scale, but low alkalinity and low pH are not a good option if you have significant corrosive chloride. This filter may have some buffering media to help keep the alkalinity and pH up. If you worry about that you could test your jug-filtered water with a KH drop titration test kit to get some idea about whether the alkalinity is staying nicely above 40 mg/L or so after filtration.

If I had a valuable reservoir machine in your tap water situation I think I would use, in order of preference:

1) 'rpavlis water' - distilled or otherwise purified water spiked with 100 mg/L potassium bicarbonate. Good alkalinity, nothing that might cause scale, and no chloride or sulfate. You could experiment with adding to that water very small amounts of Epsom salt per Barista Hustle recipes to see if that improves the coffee taste.

2) Measure the KH from the BWT filtered water and if it's well above 40 mg/L use that water mixed with distilled so that the alkalinity comes out at or around 40. If the alkalinity comes out low or unpredictable out of the BWT, ditch that system and go with a Brita longlast, which has no WAC resins and will not reduce the alkalinity, then dilute that down to an alkalinity in the 40 mg/L ballpark with distilled.

If I had a valuable plumb-in machine I would go with an RO system and a remineralizer. That would keep me OK with the most conservative manufacturer recommendations about potentially corrosive chloride even if the chloride level in my city water were to increase.

A simpler and much cheaper plumb-in option that should be adequate for most machines would be to use a particulates and charcoal filter followed by a conventional sodium exchange softening filter. These are inexpensive and easy to maintain, and would drop your calcium hardness below scale-prone levels, and would keep all that 83 - 95 mg/L alkalinity. Unfortunately it also keeps all the chloride (nothing but RO or a tricky anion exchange system will remove chloride). The high alkalinity is probably good given the borderline chloride. For brewed coffee an alkalinity that high is sometimes considered detrimental for taste, buffering down sharpness and acidity. But for espresso, using water with an alkalinity even higher than 100 mg/L should taste just fine. (See https://scanews.coffee/25-magazine/issu ... e-issue-9/ )


** The API fishcare KH kit is easy, inexpensive, and will do the trick for this. If you use a 10 ml water sample instead of the 5 ml in the kit , then 3-4 drops of titrant will correspond to 35 - 45 mg/L alkalinity.
Pat
nínádiishʼnahgo gohwééh náshdlį́į́h

Sailorman

#3: Post by Sailorman »

2) Measure the KH from the BWT filtered water and if ......
** The API fishcare KH kit is easy, inexpensive, and will do the trick for this. If you use a 10 ml water sample instead of the 5 ml in the kit , then 3-4 drops of titrant will correspond to 35 - 45 mg/L alkalinity.

homeburrero: Thanks very much for the thoughtful response - I will start by getting the API fishcare KH kit, and test my BWT-filtered water using a 10ml sample and go from there

fyi - the replacement machine is by Decent (a DE1 v1.4 hopefully to be received in December 2020) which will not be plumbed in (ie using the water tank).

Sailorman

#4: Post by Sailorman »

Once again, Pat, thanks for your response.

OK, so API kit received - as relatively inexpensive I bought the kit containing both the GH and KH tests.

I tested the BWT filtered water using 10mL (ie double the quantity in the API instructions), and got the following results:
KH : # 7 drops in 10mL = about 58ppm (pro-rating API range for 3-6 drops for 5mL = 50/100ppm)
GH : #12 drops in 10mL = 100ppm (per API conversion for 6 drops for 5mL)

I will continue to test and see how consistent they are.
    if these readings reasonably accurately represent the water I am using, am I correct in thinking I can relax and concentrate on improving my skills?

    User avatar
    homeburrero
    Team HB

    #5: Post by homeburrero »

    Thanks for measuring and reporting back! I think this may be the first real numbers we've seen for BWT jug filters. Just so we know, are you using a filter like this?


    Sailorman wrote:if these readings reasonably accurately represent the water I am using, am I correct in thinking I can relax and concentrate on improving my skills?
    If those numbers are close to what you get over the life of the filter I think you can relax. You still have healthy alkalinity to help offset that borderline chloride, and that was my main worry here.

    Your filtered water still has a total hardness and alkalinity in a zone that in typical waters would tend to drop a little scale. But in this case a high proportion of that 100 mg/L hardness may be due to magnesium rather than calcium, so I think you can just keep an eye out for scale and do periodic descaling if you see some scale accumulation on the mushroom. Also, if you use the steam wand make sure you offset the concentration effect by drawing water out of the boiler via the hot water tap*, or periodically draining and refilling the steam boiler. If you want to assuredly never need to descale, then I'd advise switching to a scale free recipe water, like the rpavlis recipe.


    * My routine is to draw some water out of the water tap before every steaming session, i.e., if I plan to steam 120 ml of milk I will pull at least 60ml of water out of my water tap before steaming. I always pull enough to trigger an autofill, that way I never get an autofill while in the middle of steaming. (When that happens on my machine, the cold water causes a pressure drop that affects my steaming.)

    Edit addition: I was thinking you had a Faema E61 (which has an easy to check mushroom). But see now you have a Eurostar, so you can't check the mushroom. I'm not sure how best to go about checking for scale in one of those.
    Pat
    nínádiishʼnahgo gohwééh náshdlį́į́h

    Sailorman

    #6: Post by Sailorman »

    Pat,
    Once again thanks for your informative responses.

    Just to clarify - my questions about water were triggered by an imminent updating of my equipment as my Faema machine was due for replacement. I have just recently received my DE1 (and have updated my profile to eliminate confusion).
    The DE1 is a different design most espresso machines which I believe reduces tendency to scaling.

    Yes I confirm that I am using the filter you referenced.
    I am delighted that my data is somewhat useful - as your input has been invaluable to me.
    I intend to re-test the water and will try to remember to post details again.

    Sailorman

    #7: Post by Sailorman »

    Hi Pat

    I retested the filtered water today and got identical results to the first measure, namely:
    ~ KH 58ppm
    ~ GH 100ppm
    NB The cartridge has #60 refills at this stage - cartridge changed after every 100 refills (which represents about 3-4 weeks elapsed time.

    FYI I also tested the tap water, (using 10mL of water and halving the number of drops used to get a change in colour) and got the following measures:
    ~ KH 85ppm (within range of official tests for 2019 - which I attached with my first post)
    ~ GH 140ppm (slightly above range of official tests for 2019)

    I guess to further lower my hardness/alkalinity I could dilute the filtered water with (say) 20% by volume of straight distilled water, which by my calculation would get me down to about:
    ~ KH 46ppm
    ~ GH 80ppm

    Thanks once again for your detailed and thoughtful responses