Well Water Analysis - Results Interpretation

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Trilitheum

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Apr 30, 2020
12
Canada
Well after a several years in the house we decided to get a full well water analysis done, mostly because there had been reports of dangerously high levels of arsenic and and barium in the region and we wanted to make sure we didn't have any issues, bonus is get to see what the full lab analysis says for the water! See attached ICP-MS lab results.
I have always had issues with fading end points in my hardness tests, even with adding 5 or 10 drops reagent before adding the buffer, I wasn't expecting the magnesium to be higher than the calcium, all the reading I have done says it's usually the other way around. My Taylor test usually gives about 375 ppm for CH, the lab reported total hardness as only 230 could the high magnesium to calcium ratio be messing up the Taylor test?

Other notables were the Sulphate, wasn't expecting that either, not super high but always using it for fill and top up water is that enough Sulphate to cause quicker fouling of the SWG?
Alkalinity was pretty much dead on with the Taylor test. Hopefully one of the water chemistry guru's can comment if I am on the right track.

Was interesting results for sure, not what I was expecting, any comments on the results welcome!

Well1.JPG
 
Calcium is being measured in it's atomic state, ie, calcium ion. So you have to convert their Ca number in to units of CaCO3 which is what the Taylor test is designed around -

Ca ion concentration = 31.9 mg/L
Ca molar mass = 40.1 gm/mol
CaCO3 molar mass = 100.1 gm/mol

CH = [Ca] x (100.1/40.1) = 79.6 mg/L as CaCO3

Same thing for the Mg -

Mg ion concentration = 36.5 mg/L
Mg molar mass = 24.3 gm/mol
CaCO3 molar mass = 100.1 gm/mol

Mg Hardness = [Mg] x (100.1/24.3) = 150 mg/L as CaCO3

Total Hardness (TH) = CH + MH = ~ 230ppm

So you can see that their "hardness" value matches up with what they measure by ICP-MS.

Your pool water is going to be concentrating both the CH and MH as water evaporates and you add more fill water. So even with your slightly hard well water (soft water definitions vary), your pool's CH will be higher. Rain and winter snow melt can be used to reduce the CH as needed. You do indeed have unusual well water with the Mg hardness being higher than the Ca hardness BUT typically reported Ca:Mg ratios are usually for terrestrial water sources. Deep wells can have all sorts of anomalies depending on what minerals the aquifer is in contact with. Your sulfate levels are pretty bad though.

Question - does your SWG ever spit out white "snowflakes"? If so, have you ever tried acid-testing them? If you acid test the white crust that builds up from an SWG, a fizzing reaction with vinegar indicates carbonate scale. However, if it doesn't dissolve in vinegar fully but will dissolve slowly in concentrated MA, then that is sulfate scale.

Your barium levels aren't that bad. Barium is not transported through or absorbed by the human gut which is why barium sulfate enemas are used for contrast imaging of intestinal related diseases. However, your lead levels are 4.4ppb and that is concerning to me. While most industrialized nations will say that value is below the threshold to treat for, modern medical opinions differ. The consensus view among doctors is that ANY PRESENCE of lead is bad for humans, and especially children. Modern drinking water filtration systems (RO filters or carbon absorption filters like Brita) can easily accommodate the removal of lead and should be used to ensure that lead levels are kept at their absolute lowest achievable value. That's not a scare tactic, it's just good public health even if the regulatory agencies choose to bury their heads in the sand.

Your chloride levels are above what most municipal water suppliers would allow and your sodium levels are fairly elevated too. Does your water have a slightly salty taste to it? Depending on how refined your palate is, some people can detect the salty taste from sodium ions down at the levels present in your drinking water. Your location says "Canada" which doesn't tell me much but are you near a coastal region or a large body of water like the Great Lakes or Hudson Bay? Or do you live way up in Yellow Knife in the NWT??
 
Thanks @JoyfulNoise for the detailed comments. Let me see if I can answer your questions the best I can.

We have a deep well about 180 feet deep, we are located in southern Ontario, inland, about 70 km from the great lakes at the closest point.
My SWG occasionally has some small flakes but nothing serious, usually just ends up with some scale on the plates themselves over time. I will try the vinegar test to see if it is sulfate scale or carbonate scale.

I did notice the lead number being slightly elevated myself, the water testing company did mention it is still within the Canadian standards, the good news is, even before we had the water tested, we have a 3 stage canister filter system on the house (5 micron sediment, granular carbon, carbon block 1 micron) This testing was done at the well head, so pre-filter.

We haven't noticed any off tastes from the water, but we are probably used to it by now, and the carbon filters could be cleaning it up some, but sometimes visitors will say the water tastes different, not bad, but not what they are used to.
 
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Good that you have a whole home filter. All well waters will have some detectable lead concentration, no way around it. Municipal water suppliers are able to get rid of the lead to below detectable levels through processing and your carbon filters will reduce any lead as well. My guess is people are noticing the effects of the sulfate when they notice a taste difference as the carbon filters won’t remove the sulfate. Sulfate can be removed by ion exchange but it requires a special ion exchange resin and the result is typically higher chloride levels. If you wanted a sulfate free water source for drinking, then an RO filter (under the kitchen sink variety) would do the trick.
 
I had looked at a RO in the past, but at this point the sulfate doesn't seem to be affecting anything, at least not that we notice, a quick google seems to indicate that at 100 mg/L its pretty much harmless.
Now the other question, we do have a water softener, I usually fill the Spa with hard water from the outside tap, would it be worth using the softened water? I guess it will only really reduce the Mg and Ca while adding more Na, but with the SWG I am dumping tons of sodium in there anyway with the NaCl

The other interesting thing is my Taylor test is way off, consistently get 380 ppm CH even when using the titrant before the buffer. The fading to purple starts around 380 PPM and ends over 450 ppm, at 80 ppm CH not even close to a color change on the Taylor kit.
 
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Sulfates won’t hurt you, just messes with your taste. What sulfates do harm is concrete. At 200-300ppm, sulfate attack can be an issue for cement surfaces. You wouldn’t want to use your well water to mix up cement with.

Increased sodium is non-issue for SWG’s. SWG’s convert chloride (Cl-) to chlorine gas (Cl2). Sodium plays no role in that process as it is simply the counter-ion. I would definitely fill an acrylic hot tub with softened water but not a plaster spa. You need some calcium when water is in contact with cement surfaces or else they will get etched. Your water is fairly soft in terms of calcium hardness so I would just use the regular fill water and not bother with softened water. Magnesium is a non-issue as well for water hardness as most magnesium compounds are highly water soluble.

As for your CH test, I’m confused - are you measuring the well water before the filter or are you measuring your pool water?
 
Trilitheum said:
I am measuring the well water right from the hard water tap the readings are consistently high ~380 ppm CH with the Taylor k-2006 test kit, reagents are new, expiry 2022.
Click to expand...

So you do the following roughly (assuming a 25mL test sample) -

5 drops of R-0012
20 drops of R-0010
5 drops of R-0011L

Sample looks purple colored

Titrate with R-0012 until the sample turns blue.

Are you using a SpeedStir?

Are you allowing the drops to fully form on the tip of the fitment and then fall off? Is the drop rate about 1 drop per second?

Do you see the sample turn blue early on and then revert back to purple?
 
Yes, that's the procedure I am following for drop additions.
I did get a SpeedStirr and it actually made the fading occur at a higher number of R-0012 drops, I thought it might be the aeration from the stirring, but I expected a cleaner transition with speedstirr and it made it worse.
I have been adding the drops slowly maybe one every 5 seconds and waiting for it to fully mix, it turns blue at around 380 PPM, not at all before, then in about a 20 seconds goes back to purple, it takes all the way up to ~450 PPM to have it stay blue.
Without the speedstirr the "first" blue then fade was around ~300 PPM

I'm wondering if something is interfering with the test.
 

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Trilitheum said:
Yes, that's the procedure I am following for drop additions.
I did get a SpeedStirr and it actually made the fading occur at a higher number of R-0012 drops, I thought it might be the aeration from the stirring, but I expected a cleaner transition with speedstirr and it made it worse.
I have been adding the drops slowly maybe one every 5 seconds and waiting for it to fully mix, it turns blue at around 380 PPM, not at all before, then in about a 20 seconds goes back to purple, it takes all the way up to ~450 PPM to have it stay blue.
Without the speedstirr the "first" blue then fade was around ~300 PPM

I'm wondering if something is interfering with the test.
Click to expand...


Yes, something is definitely interfering with the test. What you're describing is a metal ion interference - divalent transition metals like Cu2+ and Ni2+ irreversibly bind to the indicator dye and cause it to remain red. Adding the R-0012 before the buffer and dye should lock up the metal ions as the R-0012 is a stronger chelating agent than the dye but it would appear that it is having some trouble doing that. Also, you are waiting too long between drops - I would not wait at all. Simply start adding drops, about 1 drop per second to the mixing solution and begin counting, don't wait for "mixing". As soon as the red/purple color turns baby blue, call that as the end of your test. Do not wait around to see if the colors revert back.

What is the pH and TA of the water samples you are measuring?
 
SO I did a quick check with my reagents using a water source I know to be free of chlorine and metals and having a fairly common CH (the water from my fridge). I did a couple of tests - first I tested the CH of the water using the vanishing endpoint method and I got 19 drops on a 25mL sample so that corresponds to a CH of 190ppm (pretty standard CH around these parts). The water started out purplish and the endpoint transition from purple to blue was pretty quick, 18 was still a tinge of purple, 19 was blue and drop 20 was no more change in blue.

My next test was to take the same water source and add a lot of alkalinity to it (aka, baking soda). Using a very small scoop, I added a dash of baking soda and the alkalinity went up to about 350ppm (I measured it using the TA test). I then used a high alkalinity volume of water and ran the same CH test. The transition definitely slowed down such that drop 18 looked purple but then slowly started to go towards blue, drop 19 turned blue slowly and drop 20 seemed to finish off the blue transition with drop 21 causing no more change. So the presence of a lot of carbonate alkalinity seems to have slowed down the color change and perhaps caused me to read one drop higher.

My next test was to add a small amount of sulfate to the water. This is accomplished by first reducing the alkalinity using the sulfuric acid drops of the TA test and then adding in some carbonate again. The sulfuric acid adds sulfates and the baking soda adds carbonate. So I took a 25mL water sample, added 11 drops of sulfuric acid reagent (that's what the TA test says my TA is - 110ppm) and then added back a small dash of carbonate alkalinity to get both sulfates and high alkalinity water. This definitely had an effect on the CH test - even at drop 18 there was no apparent change in the purple color and the purple color did not look like the previous tests. Drops 19 through 22 also had very little change from purple to blue and then drop 23 started to get to blue, drops 24 slowly converted to blue and finally drop 25 was blue with no additional change in color. So if I were doing the test blind to what was added to the water, then I would definitely be off in my CH by 60ppm.

The above tests are really crude and not very quantitative but it does appear that high alkalinity and the presence of sulfates messes up the test a bit. It may be nothing more than it just makes the reactions slow or interferes with it a bit in terms of color transition causing the operator to erroneously read the color change. Given that your water has very high alkalinity and fairly high sulfates, it's not unreasonable for you to be seeing some odd behavior in the CH test if my qualitative tests are any proof of interference. The presence of metals would further cause issues. So I think the net take away for your water is that you have to just take the CH test results with a grain of salt and use it as a ballpark figure.
 
Wow, thanks for running actual experiments to help figure this out! I was pulling my hair out trying to figure out if I was testing wrong or if my reagents were bad as the results were consistently much higher than the lab results. For the fiberglass Spa I was only really worried about scaling up or corroding the heater and the SWG faster if my CSI numbers were way out, but like you said I will just have to take it as a ball park, and knowing the lab reported number I can guess where it is approximately.
 
Depending on how much evaporation and refills happens in the spa, your CH will definitely creep up. If you kept a total of how much water is added to it each time to top it off, it wouldn’t be too hard to figure out a rough CH number.

I would suggest you try to drop the alkalinity though with acid/aeration cycles. Having it that high has got to make keeping the pH below 8 a real bear.
 
Yes for sure, I started the TFP Bleach method, the SWG keeps things pretty much stable except when bathing load is high, it's due for a spring full drain and re-fill, I will start off fresh with a round of aeration and acid, also looking to add some borates this time around as well.
 
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