London tapwater

[Charles1968]

I'm struggling to find out the level of calcium and magnesium in London tapwater, which I need to use the water treatment calculator. Can anyone supply data or an estimate for London?

I've got these figs from my water report:
pH 7.8
Ammonium 0.122
Chloride 48
Sodium 36
Sulphate 57
Total hardness as CaCO3 261

These figs from a Salifert test:
Alkalinity 4.25 meq/L = 212.5 CaCO3

These figs from an aquarium test strip test:
pH: 7.8
Carbonate hardness: 240 or over
General hardness: 180

But I can't find magnesium or calcium cation figs anywhere...

[Eric]

Using 98mg/l for calcium and 4 for magnesium will give a balanced profile and get you going until you have a sample tested.
Be careful with those results from the aquarium test strip. A pH value for raw liquor is of limited value, but mostly the hardness figures, as general hardness usually includes that for carbonate hardness and therefore should be the larger figure.

Good luck.

[Charles1968]

Thanks, I'll use those figures. I don't trust the aquarium test strip figures as the colours were tricky to read correctly. Fortunately I don't need them.

Do you know what alkalinity I need to shoot for to get mash pH under 5.5 for a pale ale or lager? My alkalinity is 213 according to the Salifert test, which is far too high (as it's London water). I can bring it down to 44 by boiling (according to the water calculator on Brewersfriend) and can dilute with Asda mineral water (alkalinity 28 according to Salifert test), but then I think I need to put back some calcium as gypsum.

[Blackaddler]

Which water company is it?

[Charles1968]

Thames Water:

[Eric]

Thanks, I'll use those figures. I don't trust the aquarium test strip figures as the colours were tricky to read correctly. Fortunately I don't need them.

Do you know what alkalinity I need to shoot for to get mash pH under 5.5 for a pale ale or lager? My alkalinity is 213 according to the Salifert test, which is far too high (as it's London water). I can bring it down to 44 by boiling (according to the water calculator on Brewersfriend) and can dilute with Asda mineral water (alkalinity 28 according to Salifert test), but then I think I need to put back some calcium as gypsum.

For an all pale malt recipe you should be aiming at getting alkalinity down to at most 50mg/l CaCO3, preferably less. Adding extra calcium salts will also lower mash pH as well as improving yeast performance and clarity of the finished beer and alter the beer's profile.
For paler lager malts you'll wan't less alkalinity again and may not wish to have so much calcium present.
Boiling is a bit hit and miss. Using a plastic boiler I can't reduce alkalinity sufficiently, although my water has more magnesium and less calcium than yours. In stainless pots the reduction is greater as much of the carbonates stick to the metal and afterwards don't so readily go back into solution. The easiest way by far is to use acid treatment which can, depending upon choice of acid, leave the calcium level unchanged.

[Blackaddler]

If you email Thames Water, they should be able to give you the figures you're looking for.

[Charles1968]

For an all pale malt recipe you should be aiming at getting alkalinity down to at most 50mg/l CaCO3, preferably less. Adding extra calcium salts will also lower mash pH as well as improving yeast performance and clarity of the finished beer and alter the beer's profile.
For paler lager malts you'll wan't less alkalinity again and may not wish to have so much calcium present.

Thanks again. You've reminded me of another thing about water chemistry that I don't yet understand. I've read various articles that say the liquor needs a minimum of 50 mg/l calcium (Ca2+), yet when I look at target water profiles for pilsner they're often as low as 7 mg/l. Should I be aiming for 7 mg/l or 50 mg/l? I assume professional breweries have all sorts of ways of correcting problems that 7mg/l might throw up, so home brewers might need a higher value?

Boiling is a bit hit and miss. Using a plastic boiler I can't reduce alkalinity sufficiently, although my water has more magnesium and less calcium than yours. In stainless pots the reduction is greater as much of the carbonates stick to the metal and afterwards don't so readily go back into solution. The easiest way by far is to use acid treatment which can, depending upon choice of acid, leave the calcium level unchanged.

Do you know how long the water has to be boiled to remove bicarbonate? Is it just a case of bringing to the boil, or does the boil need to be sustained? I don't have acids to hand at the moment so will have to look into that in the future.

[Charles1968]

If you email Thames Water, they should be able to give you the figures you're looking for.

Thanks, I've done that.

[Eric]

Thanks again. You've reminded me of another thing about water chemistry that I don't yet understand. I've read various articles that say the liquor needs a minimum of 50 mg/l calcium (Ca2+), yet when I look at target water profiles for pilsner they're often as low as 7 mg/l. Should I be aiming for 7 mg/l or 50 mg/l? I assume professional breweries have all sorts of ways of correcting problems that 7mg/l might throw up, so home brewers might need a higher value?

No, I'm not the one to ask about calcium levels in present days, loving older style beers with lots of flavour my liquor generally has between 100 and 200mg/l calcium.
Not having facilities to brew a lager properly, I buy selected bottles.
You might care to read this and this.
Pilsner is a special case of brewing with very low ion liquor when it was found mash pH began to increase as alkalinity approached zero. Purity laws in Germany stopped the addition of acid to the mash which would solve the problem and was standard practice in UK.

Do you know how long the water has to be boiled to remove bicarbonate? Is it just a case of bringing to the boil, or does the boil need to be sustained? I don't have acids to hand at the moment so will have to look into that in the future.

The process is to boil for enough time to disperse dissoved CO2, then allow the carbonates to sediment before racking off the less alkaline liquor. Try it and check the result with your Salifert kit.

[Charles1968]

thanks. You posted the same link twice - assume you didn't mean to?

It looks like 50 mg/L calcium will work for my Reinheitsgebot-free pilsner.

will get out my salifert kit and see where a very brief boil gets me...

[Eric]

Sorry, the other should have been this.

I've corrected the original posting.

[Aleman]

I'll just say that The Czech brewers I've seen actually add Calcium Chloride to their liquor, it may not be widespread practise, but I do know some that are doing it, and they are not the big brewers either, but the small traditional ones

I normally go for around 50-75mg/l for my pilsners. . . . Of course the German Pilsner brewers reduce alkalinity with slaked lime which leaves calcium untouched

[Charles1968]

I'll just say that The Czech brewers I've seen actually add Calcium Chloride to their liquor, it may not be widespread practise, but I do know some that are doing it, and they are not the big brewers either, but the small traditional ones

I normally go for around 50-75mg/l for my pilsners. . . . Of course the German Pilsner brewers reduce alkalinity with slaked lime which leaves calcium untouched

Thanks, makes sense. I think the pilsner water profile on the Brewersfriend website (7 mg/L calcium) must be wrong.

[Charles1968]

The process is to boil for enough time to disperse dissoved CO2, then allow the carbonates to sediment before racking off the less alkaline liquor. Try it and check the result with your Salifert kit.

OK the Salifert test was definitely worth doing:

Unboiled London tapwater: 213 CaCO3
Boiled 0 mins in pan: 205 CaCO3
Boiled 5 miins in pan: 151 CaCO3
Boiled 10 mins in pan: 100 CaCO3
Boiled twice kettle: 82 CaCO3

The water knowledge page at Bru'nwater (https://sites.google.com/site/brunwater/water-knowledge) has this to say about boiling:

The practical limit for the process reduces the bicarbonate content to between 60 and 80 ppm

Since that's bicarbonate, the practical limit for reducing alkalinity by boiling would be 50-66 (using alkalinity = 0.83 x bicarbonate). That's still too high for pale ales and lager.

My kettle is doing pretty well (must be all the limescale kicking off precipitation?), but not well enough. In the past I've made pale ales with London tapwater and boiled half the volume briefly, but then found the resulting beer quite astringent. Now I know why - London water is useless for pale ales & lagers.

Will invest in some acids...