Adjusting tap water

[tonyhibbett]

Most of my kit wines end up with a pH of 4.0, which is a bit borderline. My tap water has a pH 7.8, so I was wondering how to get it down to neutral (7.0). This turned out to be 1 g of (tartaric) acid per 10 litres (roughly). So for a 30 bottle kit requiring 15 litres of water, 1.5 g of acid would be required to achieve the intended final acidity. In the case of my teaspoon, this is 1 level teaspoon. While this doesn't turn it into bottled water, it's a cheap and easy step in the right direction. A jug filter brought it down to 7.6. Boiling the filtered water increased it to 8.2, because of the limescale in the kettle, I presume.

 

[anthonyUK]

I know nothing about water chemistry for wine but for beer there is more to it than just PH.
Are any minerals levels important?

 

[tonyhibbett]

The mineral content of the soil in which the grapevines grow affects the vigour, health and quality of the grapes. The water is just to reconstitute grape juice concentrate. Ideally water with no mineral content at all!

 

[tonyhibbett]

Having added 1.5 g of tartaric acid to the 5 gallon brew, fermentation increased significantly, but the pH is now 3.0, which suggests that the dose should have been no more than 1 g. My digital scales, with a resolution of 1 g. can't measure this, so I cross referenced with a traditional balance set of scales and found that I had in fact added 2 g. Fortunately, this error has little impact on the total acidity (0.0002%).
I de-scaled the kettle but the filtered water still came out with a higher pH than when it went in, which was unexpected. This suggests that boiling water seems to increase alkalinity. As some recipes involve some boiling or using boiled water, this needs to be taken into account.

 

[tonyhibbett]

I thought I would double check. 1 g of tartaric acid changed the pH of 20 litres of my tap water from 7.8 to 7.2, so the same amount added to 15 litres would make it neutral. This in itself doesn't make the water taste any better, unlike jug filtering, so an ideal combination would be to neutralise and then filter.
For smaller quantities, it will be more accurately dosed by mixing the acid with distilled water and dividing the solution. If using 10 ml of water, then 3 ml of the solution, measured with a 5 ml syringe, would be suitable for a gallon of tap water.

 

[mabrungard]

Excessive alkalinity in tap water used to reconstitute extracts can consume the acidity you are counting on for balance. Neutralizing all or most of that alkalinity may be appropriate. But recognize that this may only be solving one problem. If the water is full of other ions, that might affect the flavor of the finished product.

The Sparge Acidification sheet in Bru'n Water can be used to calculate the acid addition needed to neutralize the excess alkalinity. All you need to know is the type and strength of your acid and the alkalinity of the water. It includes several solid acids too.

 

[tonyhibbett]

You are quite right. There is more to it than just neutralising the alkalinity. I got a water analysis from the water company and I found it quite disturbing, which is why I bought a water filter. What comes out of my tap originally contained run off from farmland, the effluent from millions of people, residue from old lead pipes and atmospheric pollution plus chlorine bleach, added in extra doses after a pipe burst, which occurs frequently. It could be argued that, due to the complex chemical reactions which occur during fermentation, stabilization, fining and maturation, that any tap water involved in the process has been transformed.
I am drinking a California Connoisseur merlot made with untreated tap water. It has a pH of 3.5 and it tastes as good as it gets!

 

[Aleman]

For wines made with extract, then you are best off using RO or Deionised water to make them up. There is no point f*ffing about with adjusting the pH of your tap water, it really will not alter teh pH balance of the wine at all . . . using pH to measure wine acidity is very very misleading because it is a logarithmic scale. . . . and example I did as a test,.

Apple juice pH 5.3 . . . Titrateable acidity 7.3ppt as sulphuric (Crab Apples)

Diluted juice 50:50 with water pH 7.0

Diluted Juice pH 5.2 . . Titrateable Acidity 3.7ppt as sulphuric

So the titrateable acidity behaved as expected when diluting it with water . . . pH does not, so in wine making as in beer making pH is of little or no practical use whatsoever.

 

[tonyhibbett]

Purified water, from the chemist, measured pH 6.6.Distilled water 6.1. 'Aqua Pura' bottled water 6.1, declared and confirmed. PH can be misleading if you compare TA (%) with a logarithmic scale, because the difference seems small, and if relying on litmus paper, probably unmeasurable. But these figures clearly indicate that you can't assume ANY water to be neutral unless you make it so. In my case, a 50/50 mix of the bottled water and tap water would do the trick. It's 6.8, which is close enough for me.
While TA is very straightforward, pH has its uses. Titration could not have told me the water was alkaline because it only measures acidity. I monitor the ripeness of my grapes using a refractometer and a pH meter in the vineyard. Very small samples are required. I am looking for changes in the sugar/acid balance. Once this gets as good as it can, I press the grapes and use titration to measure the acidity and adjust if required. Winemakers tend to use tartaric rather than sulphuric equivalents, as this is the principle acid, along with malic, which has a similar weight, in grapes. This simply means adding 50% to the sulphuric measure. As the grape ripens, the malic acid reduces, while the tartaric remains stable. This tells you how much tartaric acid you have. PH cannot provide this information.
Apples have mostly malic acid and far too much of it to be used on their own.

 

[tonyhibbett]

The final pH of the wine (Muntons premium sauvignon blanc) was 3.2, exactly the same a commercial Italian sb I tested, whereas a Winebuddy sb. made without extra acid, was 3.5. So 2 g of acid turned out to be exactly right.
These comparisons bring up another issue. The commercial wine is made from 100% grape juice, the Muntons 60% and the Winebuddy 20%. Progressively less natural acid. In the case of the Muntons, 1 g of acid corrected the water and 1 g corrected the deficiency caused by 40% less grape juice. So the Winebuddy would have needed even more acid, probably 4 g. in total.
By the same token, the kits would also be low in natural tannin. In the case of the Munton, 40%, so I added some at the standard rate for 2 gallons. The effect was subtle, but worthwhile.
Inevitably, the wine lacks the body of the genuine article, but of course is considerably cheaper!

 

[Wasabi]

...the filtered water still came out with a higher pH than when it went in, which was unexpected. This suggests that boiling water seems to increase alkalinity. As some recipes involve some boiling or using boiled water, this needs to be taken into account.

This could be due to CO2 in the water being driven off. I know rainwater is naturally acidic due to CO2, it's quite likely that tapwater has some dissolved in it too. The chlorine will also be driven off, and that is acidic in solution too.

 

[mabrungard]

+1 on what Wasabi mentions. The pH rise after boiling is typically due to driving off the CO2 which reduces the amount of carbonic acid in the water.

 

[tonyhibbett]

Thanks for that. Learn something every day. My rainwater is pretty neutral, but full of atmospheric pollution, as I live under a Heathrow flight path. The plants like it, just like they also appreciated the sulphur from coal fires in the past. I would consider using the stuff in the water butts, but the taps are clogged with black sediment!