Is neutral pH crucial in all boiler types?

September 15th, 2009, 1:21 pm

I would like to find out if, when you have a boiler made of anything besides aluminum (let us say it is stainless steel, brass or copper or those with some non-aluminum coating like nickel), is it still imperative to have a neutral pH (around 7)?

I found out why it is crucial to an aluminum boiler. I would like to know about the other type boilers now.

Apart from faster scale buildup and taste, is it at all necessary to adjust pH in order to protect the (non-aluminum) boilers from corrosion or will "unadjusted" water not cause corrosion on those other metals?

Is faster scale buildup in itself harmful to the machines, even if you descale regularly?

And with pH 7, do you get no scale at all?

Water is a whole new complicated world for me now. I am trying to understand all the ramifications of pH.

Thanks.

September 15th, 2009, 3:56 pm

You are on a slightly wrong track. The pH you measure in water can vary a lot during a few hours, since it depends on dissolved gases as well as minerals. Scaling and corrosion are more dependent on equilibrium pH, which is determined by the waters carbonate hardness, aka alkalinity. At coffee brewing temperature, just off boil, an alkalinity of 50 mg/L is required for neutral equilibrium pH and no scaling. At steam boiler temperatures, you are down to 25 to 30 mg/L. Regular calcium hardness is also a factor for scaling, but not for corrosion.

All boilers can collect scale, and normally you want to keep water slightly soft (and slightly acidic) to control it. All single metal boilers, including aluminum ones, are relatively corrosion proof, although stainless is best, brass/copper is good, and aluminum is only fair.

What kills Gaggias is galvanic or anodic corrosion -- if the water is slightly acidic, i.e. soft, the mating between the brass group and aluminum boiler acts as a battery and the aluminum side corrodes. In most places, the water is hard, so this isn't a problem. Your best bet in a soft water area is to get another machine or add a 1/2 cup per liter of Evian to the tank whenever you refill it. Baking soda would be a really tiny pinch. The packets sold by Cirqua are a more designer possibility.

None of this would be measurable with a pH meter. Use a TDS meter and get it above 75. If your water is already above about 50 mg/L, you will not have a severe corrosion problem.

September 18th, 2009, 2:28 pm

Wow-Jim. I have been trying to formulate my reply, still coming from a position of lack of full comprehension of all this stuff. I had already read through half of your "insanely long FAQ" before posting my question. I do have problems fully understanding the science and the math of it all.

So here is my insanely long reply with so many more questions. This is partly because it is so incredibly difficult to try to discuss a complicated matter, or any matter where questions beget more questions, via online discussion.

Can I try to clarify some more, and please forgive me if I sound like I am repeating any question. It may be that I didn't know it was answered or I didn't see that. I am really an "accidental barista" in that I really want the best espresso drinks I can make at home, but I am not at all mechanically or scientifically gifted so I struggle with the technical explanations. I truly hope to come up with the most simple solutions to my issues. One more factor is that--without going into long detail--my current living situatioin makes acquiring bottled water (especially of a specific brand) quite unfeasable, so if I need to alter my water, I am trying to find out if I can do it all myself. Or if I can just plain use my Brita water without damaging a stainless steel or brass/copper boiler (my future machine).

First, let me say that we can forget about the Gaggia--I am not ever going to use an aluminum boiler again. No need to go into that anymore. So, let us assume that I will use either a stainless steel or brass or copper boiler in future.

Given that information,
First: Can I assume that I do not even have to worry about corrosion , even if I just used my Brita water and did nothing to alter it?

Second: Is it ok to use "regular" (Brita) water and descale regularly (maybe once a month--pulling about one double a day)and in so doing take care of scale that way, rather than total prevention of scale? If not, what is the danger of not doing "scale prevention"?

If the answers still say I must not use just Brita water, I have questions about your previous reply to my post.
1)What is a TDS meter?
2)If the TDS meter gives me a reading saying I need to alter things (I assume you mean hardness?)--will I be able to alter that myself? And how?
3)Should I be altering my pH every day to be 7.0 ? (Although you seem to say in your article that the pH I measure before heating wil be different thant he pH in the heated boiler,,, so I don't know how one could predict what pH to achieve for that...
4)I keep being told that the pH of Brita water is on the acidic side, which in part of your answer you seem to say is desirable to prevent scale (I don't know if Brita pH falls in "slightly acidic"-what number pH is slightly acidic?)So doesn't that mean that the Brita water should be good as a scale preventer?

You also say if I am in a soft water area (can I assume I am the equivalent if I use the Brita, more acidic, water?) I should add a tiny pinch (that would mean like an 1/8 teaspoon?) of baking soda? (or the Evian if practical). Was that just for the Gaggia you were saying that, or should I always add the baking soda with stainless or brass/copper too? B/c that would make the water less acidic from waht I understand and orginally you mention the slight acidity is good, so I am getting all confused.

Bottom line: let's only focus on stainless and brass/copper boilers in terms of what water I should put in them when I get my next machine. If I can use the Brita water and not harm my boiler or my health with unwanted substances coming out of the boiler (like metal) that would of course be preferable. If not, please try to clarify.

Sorry for such a long and detailed query--I don't know how to shorten it since these are all things I still don't understand.

Thanks so much for your help. I think one reason no one else replied is that you have gained the reputation as the "water expert".

September 18th, 2009, 3:01 pm

[quote="EspressoGirl"I am not ever going to use an aluminum boiler again.[/quote]

Yep; that happens a lot.

If the answers still say I must not use just Brita water, I have questions about your previous reply to my post.
1)What is a TDS meter?
2)If the TDS meter gives me a reading saying I need to alter things (I assume you mean hardness?)--will I be able to alter that myself? And how?
3)Should I be altering my pH every day to be 7.0 ? (Although you seem to say in your article that the pH I measure before heating wil be different thant he pH in the heated boiler,,, so I don't know how one could predict what pH to achieve for that...
4)I keep being told that the pH of Brita water is on the acidic side, which in part of your answer you seem to say is desirable to prevent scale (I don't know if Brita pH falls in "slightly acidic"-what number pH is slightly acidic?)So doesn't that mean that the Brita water should be good as a scale preventer?

1) A TDS meter measures the electrical coinductivity of the water, and based on that, worls out the Total Dissolved Solids (aka TDS). Neutral hardness water, good for coffee, is at around 100 to 150 TDS.
2) New York gets its water from two sources. Finger Lakes water is soft, Jersey water is suitable for coffee as is.
3) The pH of water changes as it absorbs or releases gasses, and measuring the pH is a waste of time. If you let the water stand at room temperature in still air, it will eventually reach equilibrium pH, which is based on the carbonate hardness or alkalinity. There is no need to measure it unless you are keeping tropical fish or doing a product test.
4) The Brita filter is a charcoal filter and a heavy metal remover. It does remove some calcium, but not much. If your water has a funky taste, use a charcoal filter like Brita or Pur, otherwise the whole thing is optional. Once the water stands for an hour or two, especially in a warm espresso tank, the chlorine is gone.

TDS meters cost around $15 if you Google. It is worthwhile getting one to check your water. It is also a must if you ever treat your water using a purification system (but they don't work for simple salt based ion exchange softening systems).

Descaling is quick and simple on a single boiler espresso machine. Use water at 100 mg/L TDS or higher and descale regularly. If you get a machine with a steam boiler, like an HX or double boiler machine, descaling becomes more of a chore. This is why I wrote the water FAQ. Back when I wrote it, vendors told buyers never to attempt to descale their HX machines. The whole thing has become a lot less mysterious now, and I recommend using good coffee water and flushing and descaling. As a second best, for pourover machines, I recommend using purified water like from a supermarket automat or the Zerowater cartridge and adding back tap water to get around 75 TDS on your meter. This will reduce scale build up so that it can be done every five years or so.

The Zero Water people even throw in a feebie TDS meter if you buy their jug.

Nicholas ("Shadowfax") is bringing the FAQ up to date by looking at some more recent water treatments; you'll find the his threads in the Knockbox. I posted on the Zero Water in Tips, and will join Nicholas in looking at some of the current water options.

All in all, it's a lot easier getting near perfect water for both plumb-in and pour-over machines now.