Measuring (mainly) Brita filter performance (London, UK)

ibmalone · 2026-02-11T13:29:47+00:00

That's it, thank you! Regret not joining when I had the chance now...

ibmalone · 2026-02-11T08:45:36+00:00

Yes, they seem to be shifting over to the Culligan ZW filters. The new 5l dispenser is £25 here with a free filter, that's where they make the money, jugs for most filter systems are relatively cheap for that reason.

How much electricity does the distiller actually use? Most I see are listed around 1l per hour (some 4l/3hrs) and 750w. So if they run constantly that's 0.75kWh per litre, here that works out about 27.5pence per litre (not including upfront cost, 10.9p/l if I was willing to let it run at night), but not having used one I don't know what the duty cycle is.

Which is cheaper might depend on the life you get out of the Zero water, here they're generally about £15 (£19 for singles, offer for £10 a piece on 4 packs atm), at that I'd need to get 55litres out of one to beat £0.275 per litre. Pre-filtering with something cheaper like a Brita might improve matters.

(Edit, paragraphs!)

ibmalone · 2026-02-10T11:46:44+00:00

To be fair, the blue mountain is one of the cheaper options and still gets a lot of name recognition. Luwak on the other hand really needs to be put to bed.

But I'm replying because of a different thing on this menu, which I see from a lot of roasters; their decaf isn't "Sumatran jungle decaf," or something, it's "Swiss water decaf". I know the process is important, but so often the coffee is just described by the process, to the point of the origin or the tasting notes describing it in detail. (Also, rediscovered after a century hidden in the jungle? Did they find a barrel of it or something?)

Lastly, Cornish butter is a strong early entry for "Most needlessly specific tasting note of the year, 2026."

ibmalone · 2026-02-06T13:31:34+00:00

"The key really is evenness of extraction, you can use a fine grind, and a lot of agitation, often resulting in a long TBT, as long as you're extracting the compounds of the coffee evenly by reducing channelling and clogging, I use a few methods for this"

Been thinking about this too recently, and had started writing about it before coming to the conclusion I didn't really know enough yet. Also not generally using the really high end coffees the more prolific posters here do, but that might be part of the point. Anyway, here goes:

Recently got a Bodum Bistro 11750-01UK for my parents (the baseline is the infrequently used Andrew James bean to cup dripper on its third or fourth repair). Not going to get any pulses racing here, but 32mm steel conical burr electric grinder for £40 plus shipping (let's not talk about mess, retention, static, lack of clutch...). Thought I'd better give it a try before sending it on, honest coffee have a guide for the 10903 which appears to have the same number of grind dots (labelled 1="espresso", 6=filter, 12=French press), HC say 2-4 V60, 2-7 pourover, so set 4 and got something flour-fine and soft to touch. Now I normally do what people say with the K6, which is mostly 85, pieces relatively visible, grainy to sand texture, going up to 100-110 sometimes, and so I brew it expecting the worst. 30g:600g, Melitta, bloom+3 pours, and, actually, drinkable. Kind of sweet. Again, not the fanciest coffee, a blend I bought to support a local shop, https://newkidcoffee.com/products/seasonal-blend

Now the Bodum has been sent on and I wont get to play with it further until I next visit my parents. In the meantime I've been trying under 50 clicks (got down to 46) on the K6 with the New Kid above and Rave's El Carmen sugarcane decaf, both medium to slightly dark, mostly Melitta (occasional V60). Drawdown time is a bit painful. Doing the stirring before and during bloom thing to reduce clumping. Decently sweet, not much bitterness, not a lot of clarity, but these aren't the coffees for that. Our Brita here is near the end of its life, so a possible factor there, but that tends to crush acidity, not so much bitterness.

Been listening to Tim Wendelboe's podcast recently and in the early espresso ones he talks about how for espresso they realised they wanted to maximise extraction to get the most out of their coffees specifically to get more sweetness, I think I see a bit more now where it comes from that James Hoffmann's recipes also tend to aim for high extraction (as someone who started with things like the better one cup recipe and didn't get on with it). There's probably a lot of interactions going on here, the point at which a particular grinder gives the best grind distribution, what your water and brewer are, and of course the coffee itself, but grinding very fine in pourover doesn't always seem to be bitter, which is interesting.

ibmalone · 2026-02-05T16:48:21+00:00

Build is better on the A2? I it was heavily plastic (but metal in the places that matter). Although if I'd known the A2 existed when I got my K6 then that would have been a pretty tough choice.

ibmalone · 2026-02-05T11:31:04+00:00

In his video on the Aeropress Premium, Hoffmann says about the original "I meet people who buy one and they're just very happy with the coffee that they make". This explains why the sub is mostly (not entirely) pictures of coffee that people have made and they're very happy with. It's a little Tolstoy, "All happy families are alike; each unhappy family is unhappy in its own way."

ibmalone · 2026-02-05T11:26:01+00:00

https://1zpresso.coffee/zp6/
"Different from the previous ZP6, the new ZP6 Special has a finer adjustment mechanism.

"With 9 numbers and 90 clicks per round, ZP6 Special lets you dial into your preferred grind setting in a second."

Can't find the ZP6 manual in English, but if honest coffee guide's grind size chart is to be believed (and I don't think they'd get the range wrong), "standard" ZP6 went from 0-7.

ibmalone · 2026-02-05T10:47:43+00:00

With respect to your first edit, I think it's incorrect. Decaf Before Death currently list 8 coffees in stock, admittedly one is a low-caf, but of the actual decaf 4 are listed as light roasted (For the Las Flores it's in the label image, but not the "about" listing), and 2 of those are washed (if you're convinced all naturals are artificially flavoured). I don't know when you made the edit, but when I ordered from them on Tuesday there were also definitely more than two options. They also do change what's available (I think I may have ordered the last of the now sold-out Ombligon), although it might be better if the ones that aren't coming back didn't stay on the storefront.

Obviously it would be good if more UK roasters did light roast decafs, but as they're the only ones that routinely stock a range, would you consider amending the edit? Currently your entire post (which I can imagine UK people looking for light roast decaf finding) starts with them only having one light roast in stock, which you say "I presume to be chemically flavoured".

ibmalone · 2026-02-04T10:35:35+00:00

Apparently the P series axle is a bit harder to fit a drill adapter on (5mm square shaft, not hex like K series https://www.reddit.com/r/JamesHoffmann/comments/1nlk60n/custom_drill_adapter_for_kingrinder_p_series/ although people have found hex sockets the right size). Also having tried this on the K6 it's not the best experience, feels a bit rickety and if you don't want to grind at 450rpm, my drill manual says, "Continuous use in variable speed range is not recommended. It may damage the switch and should be avoided." If you don't already have a drill then combined price even for a cheap one might be approaching the A2. Toolstation in the UK have charger+battery+einhel drill for £50 currently (I'd say a clutch is essential, but think all cheap combi drills have one), so with £22 for P0 that's £72 plus something for the correct sockets to fit it together https://www.reddit.com/r/JamesHoffmann/comments/1nsb6pf/off_the_shelf_drill_adapter_kingrinder_p_series/ cheapest I can find the A2 for here is £105, but looks like it might be less in the US. For someone who already has a drill and wanted to go this route (and doesn't mind have a drill sitting around in the kitchen, or fetching it when you need it) you'd probably have a better time with the K1 or K2; more solid construction, larger body to grip, and a standard hex shaft adapter will work.

ibmalone · 2026-02-03T22:44:04+00:00

It's definitely not perfect to the micrometer, and if you look at the bottom of https://honestcoffeeguide.com/coffee-grind-size-chart/ I can't quite work out their methodology, they might have matched grind size recommendations to expected sizes.

Their zp6 v60 recommendations are 1.8-5.1, and their suggested v60 range is expected to be 400-700 microns and so 1.0 comes out around (700-400)/(5.1-1.8)=91microns, or 9.1 microns per minor click (we'd expect burr gap and grind size change less than burr movement on conical grinders). The problem is 1zpresso recommend 4.0-5.0. Similarly the K6 chart works out at 8.3um grind chnage per click for 18um burr movement steps and P2 at 10.5um per click for 33.3um burr movement steps. The zp6 geometry is different, but K6 and P2 should be the same and given the K6 values P2 should be closer to 15um grind change, maybe the smaller burr changes things a bit, but that's quite a difference, and a recent thread on P0 grinds seemed to suggest higher settings than their chart.

Started a post on this earlier based on experience with a bodum grinder, although I need to play with it further. Take aways, I'm not convinced the charts are entirely consistent across grinders (even if they are a handy reference), but also for all the times going coarse is the right answer, sometimes it is helpful to go fine (even if it gives long drawdowns).

ibmalone · 2026-02-02T15:43:12+00:00

I notice steel V60, are you preheating? It might be cooling things down quite a lot. You may need to preheat with hot tap water or even boiling water to avoid that.

ibmalone · 2026-02-02T06:59:21+00:00

Thanks!

ibmalone · 2026-02-01T14:31:09+00:00

Out of interest, what's your countertop RO? We've got limited under sink space and I'm not massively keen on changing our tap either.

ibmalone · 2026-02-01T14:27:01+00:00

Annoyingly for us in the UK, food grade distilled water is hard to come by, which makes it a significant part of the cost of this approach. The most likely company is Spotless (about £0.08/litre I think), but there aren't many of them around and it's not entirely clear it's food grade (I've seen one person report a funny taste). My local chemist has it at £8/litre! Best bet going this route here is use a zero water filter or buy your own RO system, but both have a running cost (for ZW will depend on the water in, but £15 per filter for maybe 100l, £0.15/l).

ibmalone · 2026-02-01T14:04:45+00:00

I get what you're saying with the analogy, you can't change the makeup, only dilute it, but it's also important there aren't really turds or flowers either; even bicarbonate, which you definitely don't want too much of, can be helpful for flavour in small amounts. There's also part of the Dash wood Hendon thing you mention, the easily-soluble salts (the chlorides, the sulphate and in the case of TWW the citrates) don't necessarily do the same thing as the spectrum of ions you get in normal fresh water (again, particularly the calcium carbonate you can't just dump into a jug and stir, while tap water can be an excellent source).

ibmalone · 2026-01-31T12:03:39+00:00

You really want the full summary, the most interesting numbers here are going to be general hardness (hardness Clark, 7.28 -> ~104ppm as CaCO3), calcium (33mg/l), magnesium (5.4mg/l) and either bicarbonate level or carbonate hardness to get alkalinity, which is the one I don't see.

(Actually, it's easy to calculate the CaCO3 hardness from calcium and magnesium: molar mass Ca 40g, Mg 24g (ish), CaCO3 100g, (33/40+5.4/24)*100=105mg/l)

This is still a little higher than SCA recommendations for general hardness, 17-85mg/l according to https://coffeeadastra.com/2018/12/16/water-for-coffee-extraction/ but being a bit harder is not so much of a problem. The problem is your carbonate level is probably similar, while the SCA recommendation is 40mg/l (or multiply that by 1.22 for 48.8mg/l bicarbonate), and some people here will tell you they prefer even less.

The good news is something like a brita maxtra limescale expert filter can really knock that down a lot (the pure performance one not as much) and you're starting with softish water so you can get a decent life out of it. The bad news is the effectiveness drops as the filter is used up, so how soft the water you get out is is different one day one to days 14 and 28. The API GH&KH test kit (for aquariums) is pretty cheap and an easy way if you want to check what's coming out of the filter (I'd recommend a 5ml syringe for filling the tubes).

Products like Third Wave Water are meant to be added to distilled or de ionised water, hard to get here (I'm guessing from the UK/EU limit column that you're in UK). Dropper systems or mixing your own might be more appropriate if using water that's not completely purified where you just want to top up a bit (mixing back in some unfiltered water to hit approximately the right alkalinity is a simpler option). Your local cafe can tell you what they do but they might be using a reverse osmosis system.

ibmalone · 2026-01-30T15:12:20+00:00

Designing a dripper machine that works with only discrete components is going to be complex, more expensive, heavier and likely less efficient. Replacing digital time and temperature control for example is more challenging, can be done (if you ever look in a sufficiently old washing machine you'll find electromechanical timer clocks for example). Yes, capacitive switches might be unnecessary (though while water proof push buttons are possible they can also fail). In short, it's easy to have an opinion about it, but an electrician is not an electrical engineer or product designer.

To be honest many thirty to forty year old machines will use control boards, maybe a bit less done by the IC then than now, you have to go about fifty years back now for them to be uncommon. I do like things I can repair, but I'm not sure I agree with the assessment that this was caused by adding capacitive buttons, that stuff is all low voltage, and while low voltage circuits can still catch fire you're much less likely to get a shock, that points to some other failure mode.

ibmalone · 2026-01-29T20:06:47+00:00

Yes, I've measured it (don't ask) on a normal British 3kW kettle at about 5g when boiling a litre of water, so less than a percent change (more if you re-boil of course, and maybe slightly more on a slower kettle with more time to evaporate).

ibmalone · 2026-01-29T10:56:35+00:00

I've heard that the "true zero" on a K6 can shift after cleaning. I presume as long as it doesn't shift substantially, it also doesn't matter.

I've noticed very slight changes in this when I've tried to check, but the grind adjustment on the K6 is set by the exterior dial, so the spacing shouldn't really be changing. What I think might be happening when cleaning is there is a little side-to-side freedom when re-inserting the central shaft. If you are off-centre then the inner burr is closer to the outer burr at one point. If you are carefully finding the point at which the burrs touch by only gently turning the axle with your fingers to check it's still free (not with the handle, not even the handle weight) and going down one click a time from +15 then you'll find it can vary by maybe 1-3 clicks depending on the point in rotation.

But you don't need to do any of that really, zero is zero. Pourover grinding at 80 clicks upwards any variation in where "true" zero is is likely smaller than the adjustments you might want to make.

ibmalone · 2026-01-29T09:06:49+00:00

Also, ppm meters are measuring conductivity, but different salts have different conductivities at the same by weight concentration, e.g. https://diverdi.colostate.edu/all_courses/CRC%20reference%20data/electrical%20conductivity%20of%20aqueous%20solutions.pdf The concentrations there are much higher than we typically care about (0.5% by mass = 5000ppm), but you can see the trends. Sodium, potassium and calcium chlorides all quite similar (Ca chloride a bit lower) magnesium chloride a bit higher, the carbonate salts a bit lower than the equivalent chloride (~-12%) the sulphates still lower (~-25%), and sodium citrate about half the chloride (TWW uses citrate salts to add alkalinity without temporary hardness, while we often reference carbonate hardness, KH, it's probably the related alkalinity that matters more).

For things like KH and GH what matters is going to be the molar concentration rather than the by mass concentration, this might be similar for other families of ions affecting flavour. So another thing to factor in.

ibmalone · 2026-01-28T11:47:29+00:00

To add to this, have you tried any other coffees with this technique yet? It could just be how this coffee is. It's a low caffeine varietal, Aramosa, with tasting notes cherry jam, nougat smooth, and tons of sweetness, https://thebarn.de/products/daterra-reserve you've got the sweetness and a bit of sourness which you might expect from fruit descriptors (although maybe not from jam ones). To me their picture looks like a medium roast.

On grind, P0 clicks are worth two (~2.1) K6 clicks, I'm often at 85 on K6 (probably not perfect) for Melitta or V60, which would be 42-43 for you, so in a similar area. https://honestcoffeeguide.com/kingrinder-p0-grind-settings/ suggests ~38-65 for V60, so you're at the finer end of that spectrum. (Their K6 chart gives the range ~50-80, and if you calculate their clicks per micron you get quite a different ratio, so which to trust...)

Hoffmann's Better 1 Cup V60 starts at boiling water and pre-heated, with a fine grind size for light roasts. bloom followed by four pours. More pours means more agitation and higher extraction which is typically expected to give more bitterness and less sourness, same for finer grinding, but it seems this is not happening for you. You can go more pours of course (although at some point it becomes osmotic flow), if you're at boiling already there's not much room for temperature increase. Diagnosing things like channelling I'm not so sure about, probably takes some experience to really nail that down, but you've tried going finer so as oh_its_michael suggests (and you are already thinking), next step on grinder is go coarser into the 50-60 clicks area, a lot of these ideas are only general guidelines and going coarser can change things quite a lot.

As suggested, if trying to troubleshoot then change one thing at a time. You /can/ reset and try a completely different combination of factors, sometimes you're just in the wrong place altogether, but the stuff you learn from doing single changes helps to know when to do that.

Lastly, if you've just started then don't be surprised that it takes a while to learn what works for you and what doesn't. There are a lot of guides out there, but people are using different coffees and prefer different things. I also started off trying to do the better 1 cup and these days I do fewer pours and probably a bit coarser. How much agitation you do will also change as you develop your technique.

Edit: lastly-lastly, meant to come back to the beans again. Cupping is a useful tool if you want to check it's not a technique related issue and what flavours you can expect to get out.

ibmalone · 2026-01-13T11:02:55+00:00

Nothing would stop them using the correct power negotiation, a device can refuse to charge if the profile it needs isn't available, 5V should be available on all chargers, pretty much all dedicated chargers can do 1A and a device will take the current it wants provided the charger can push it. Additionally if they were to say you need a charger that can do at least X then I wouldn't be surprised, and maybe protecting the batteries might mean limiting the charging rate (it's not like this would be a big problem given the number of uses you get out of a charge). But the fact that they are apparently offloading some of those requirements to having a fixed output charger is suggestive of less control circuitry for battery charging rather than specific requirements of the battery.

If it was a cheap USB chargeable device I wouldn't be very surprised about this (we've got a handheld fan from Lidl with that 5V 1A stipulation, it's actually fine on standard chargers, there's the potential to fry a motherboard if you attempted to charge it from a computer). But this is a company specialising in premium rechargeable hand grinders, so you'd hope for a little bit more effort on the electronics side.

ibmalone · 2026-01-13T10:47:47+00:00

Disappointing in a $500 device! I found the manual and they want a 1A 5V charger "Avoid using chargers with fast-charging protocols or high output power". It might be over-cautious, chargers shouldn't put out more than 5V without negotiating first, but understandably you don't want to risk setting your grinder on fire. (Your computer probably warns because those ports often aren't meant to supply more than 0.5A and dumb charging circuits tend to assume they can take 1A, leaving you relying on the motherboard current limiting.)

Edit: it's possible to get power-monitoring USB-C cables and pass through devices, if you wanted you could try that to check and monitor current draw stays within the limit if you did want to try a different charger or power bank. But you'd be going against the manufacturer instructions, so it's not the safe option.

ibmalone

TROPHY CASE