Magnesium level in Severn Trent water

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cc986
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Magnesium level in Severn Trent water

Post by cc986 » Tue Mar 15, 2022 3:59 pm

Hello,
I asked Severn Trent for an updated water profile today and the result they gave me shows that the magnesium level has risen from 8.3 mg/l to 37.76 mg/l in the last year and half. That seems like a lot to me so I asked them to check it and they confirmed it was correct and that the water hardness must have increased since the last report.
Anybody know if that amount of increase is normal?
Thanks.

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Eric
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Re: Magnesium level in Severn Trent water

Post by Eric » Tue Mar 15, 2022 5:06 pm

No, it certainly isn't. Has other mineral content also changed to readdress what would otherwise cause an imbalance? Can you post the analysis you have?

All limestone deposits contain some magnesium, but usually the proportions vary little in specific regions. Magnesium salts are more soluble than calcium salts and have found magnesium content of my water to be more consistent than that of calcium.
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Re: Magnesium level in Severn Trent water

Post by cc986 » Tue Mar 15, 2022 5:55 pm

Thanks Eric. I took most of the info off their public website where they publish everything apart from Calcium, bicarbonate and Magnesium so I contacted them and asked for those. The only things that have changed more than one or two ppms is the bicarbonate which has risen from 119.73 to 189.81 and Calcium which has risen from 47.21 to 62.23.
https://www.stwater.co.uk/my-supply/wat ... r-quality/ (postcode is DE223LX)

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Eric
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Re: Magnesium level in Severn Trent water

Post by Eric » Tue Mar 15, 2022 10:04 pm

Right, I'm struggling and writing this on the hoof.

I follow all you have written, any contempt that comes across from my post is for the water company or the persons involved in providing the data.

From the website...
Source of water
The supply to this area is from a blend of sources from our East Midlands Strategic Network
If that is always the case, you will have an uphill struggle to know the exact makeup of brewing liquor over time. That isn't the end of the world for brewing good beer as many would have you believe, but it won't make life easy if it is, and almost as hard if it happens occasionally. So what do we know?

They give hardness as 15.55 French degrees, that's 155.5 ppm as CaCO3 to you and me, but they give it for every period, despite given major ion quantities typically varying fourfold over all periods. If the water varies by that degree, how could they give you a values for calcium and magnesium to 2 decimal places. Were you talking to a smartarse?

The quantities of sulphate for 3 samples taken during the month of Dec 2021 were, well so the table says......

Min 32 mg/l Ave 47 mg/l Max 77 mg/l but is that true.

3 reading with an average of 47 would total 3x47 = 141.
Total of Min and Max = 32 + 77 = 109.
So the other test must have been 141 - 109 = 22 mg/l.


Put simply, I don't trust their numbers, but it is also likely that your water varies enormously to mean any given values are purely historic and of little value to the brewer.

I would advise, if you don't have one, buy a cheap TDS meter, you don't need an expensive one. I think they have gone up, I got 2 for less than £10 and have been worth their weight in gold. The readout you get will not measure the actual Total Dissolved Solids in your water, they are usually calibrated for common salt solutions, but they will detect variations in your water's mineral content. Mine can vary enormously, but for most of the year it doesn't, changing only in times of severe drought or in prolonged periods of heavy rain. A record of daily readings will confirm or otherwise, changes in your water. If it is mostly consistent, get a sample analysed and use those figures.

Also if you don't have a Salifert KH test kit, put that to rights. It will enable you to measure alkalinity allowing you to adjust that with acid such as CRS. You could then compare variations of the TDS readings and those for alkalinity to see if they are in phase with one another.

Good Luck.



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Re: Magnesium level in Severn Trent water

Post by cc986 » Wed Mar 16, 2022 9:44 am

Thanks very much Eric - that's great advice and I will get that equipment. I have a feeling that the person I was speaking to was only passing on information so I have asked them to go back to the source and challenge the accuracy.
Thanks again.
Chris

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Eric
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Re: Magnesium level in Severn Trent water

Post by Eric » Wed Mar 16, 2022 12:38 pm

cc986 wrote:
Wed Mar 16, 2022 9:44 am
Thanks very much Eric - that's great advice and I will get that equipment. I have a feeling that the person I was speaking to was only passing on information so I have asked them to go back to the source and challenge the accuracy.
Thanks again.
Chris
I hope I haven't set Seven Trent on a warpath against you, being able to measure and quote alkalinity to 2 decimal places is a total pipe dream when the end point of alkalinity is incredibly difficult to accurately determine and utterly unnecessary for any practical purpose I can imagine. Then how come they can't correctly list 3 readings or cannot calculate their average properly. However, if your water does come from multiple sources, any figures they can provide will be of only limited use for your task in hand.

When you have any new figures, give a shout.
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Re: Magnesium level in Severn Trent water

Post by cc986 » Wed Mar 16, 2022 3:18 pm

I just received a phone call from Severn Trent and they are certain the magnesium level is correct. They say that when I asked for the levels in 2020 the magnesium at that time was quite low compared to normal and that it has risen significantly over the past year but has dropped slightly recently. They also said it wasn't unusual to see such big increases.
I've ordered my TDS and Salifert kits.


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Re: Magnesium level in Severn Trent water

Post by PeeBee » Wed Mar 16, 2022 3:45 pm

A million years ago (give or take a few years) I lived, and brewed, down there (Ockbrook & Borrowash). I left about the time of the fiasco with Carsington Reservoir (which included the dam wall collapsing at one point).

I don't know if your water is extracted from the River Derwent (the means of accessing Carsington water), but I do remember environmental concerns about mixing White Peak and Dark Peak waters (via near impossible to build tunnels through massively fractured geology). The mixing would explain regular swings of water salts with the Derwent Reservoirs, Dark Peak, source of Derwent and very low in salts especially Magnesium, and Carsington, an exceptionally large storage reservoir for the Derwent but sitting in the Magnesium rich White (limestone) Peak.

Just speculating (or perhaps just sticking the boot in as I no longer rely on that - foreign - water authority).

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Re: Magnesium level in Severn Trent water

Post by cc986 » Wed Mar 16, 2022 3:54 pm

PeeBee wrote:
Wed Mar 16, 2022 3:45 pm
A million years ago (give or take a few years) I lived, and brewed, down there (Ockbrook & Borrowash). I left about the time of the fiasco with Carsington Reservoir (which included the dam wall collapsing at one point).

I don't know if your water is extracted from the River Derwent (the means of accessing Carsington water), but I do remember environmental concerns about mixing White Peak and Dark Peak waters (via near impossible to build tunnels through massively fractured geology). The mixing would explain regular swings of water salts with the Derwent Reservoirs, Dark Peak, source of Derwent and very low in salts especially Magnesium, and Carsington, an exceptionally large storage reservoir for the Derwent but sitting in the Magnesium rich White (limestone) Peak.

Just speculating (or perhaps just sticking the boot in as I no longer rely on that - foreign - water authority).
That's interesting and might well explain why ST don't see anything unusual in big changes.

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Re: Magnesium level in Severn Trent water

Post by Eric » Wed Mar 16, 2022 5:17 pm

cc986 wrote:
Wed Mar 16, 2022 3:54 pm

That's interesting and might well explain why ST don't see anything unusual in big changes.
That certainly does.

That ST comment about magnesium is encouraging. Firstly don't worry too much about magnesium spoiling your beers, it will give it a characteristic, but malt adds substantially more than will your water, so the increase is less than might be first though. I live on Magnesian Limestone with water containing more magnesium than yours will likely ever have. PeeBee might comment on the influence of magnesium in my water. But most important from today's call was that the amount of magnesium in 2020 was low compared to normal and has dropped slightly recently, suggesting the water could be more consistent than their other data implies.

The TDS meter, despite the precise reading being of little immediate practical value, should quickly give you a sense of any variation and an idea of the proportion of any variation. Try to have the meter and the water sample at the same temperature and let the reading settle. Take as many as convenient and keep a record. Don't bother with an alkalinity measurement for every TDS reading, keep those for the highest and lowest TDS readings. Hopefully any variation will be relatively small, time will tell.

The Salifert kit will enable you to suitably alter the level of alkalinity in your water to suit the type of beer you brew.
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Re: Magnesium level in Severn Trent water

Post by cc986 » Wed Mar 16, 2022 8:04 pm

Thanks for the advice again Eric!

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