TDS isn't all that relevant. In addition to the chrloride figure, you need to know the carbonate hardness and alkalinity in order to determine what kind of softener to get. Suggest you read Jim Schulman's Insanely Long Water FAQ.

godlyone wrote:So from what I'm seeing pH 7.2 corresponds to Alkalinity 65

No, it doesn't work like that. If you know the alkalinity but not the pH, you use the equilibrium pHeq to do your scale estimate calculations. But it doesn't work the other way around. If you have a pH measurement you can't use that as a reliable indicator of alkalinity. The pH of the water is related to alkalinity but is strongly affected by the amount of dissolved CO2 and associated carbonic acid which can vary quite bit in water coming out of the tap.

If you have a number for bicarbonate ion in your water report you can multiply by 0.82 to get the alkalinity in CaCO₃ equivalents. e.g, 100 mg/L of bicarbonate ion (HCO₃⁻) is an alkalinity of 82 mg/L CaCO₃ equivalent.

homeburrero wrote:The pH of the water is related to alkalinity but is strongly affected by the amount of dissolved CO2 and associated carbonic acid which can vary quite bit in water coming out of the tap.

Yes! Here in the East, water from wells in rocky areas is likely to contain dissolved CO2 and carbonic acid due to the effect of acid rain on limestone. The carbonic acid inflates pH readings of cold water. The CO2 comes out of solution when the water is heated, which will result in a higher pH reading.

I'm surprised your report doesn't include carbonate hardness. If it's not there, I strong advise you to get a good quality hardness testing kit before selecting a softener. I think the Hach hardness testing kits are the best. This one is good for measuring larger amounts of hardness, which is pretty likely in well water from rocky areas. If you want to measure very small amounts of hardness, such as what you get after using a softener, then you should get this much more expensive kit. Unless you're OCD like me, it's not really necessary, since the less expensive kit can tell you if the hardness has climbed to a level that will produce scale (i.e., the softener cartridge needs to be changed or recharged.)

Note that the level of hardness in well water can vary (it does in our well water), so it's good to check the softener output on a regular basis. Our alkalinity level stays pretty constant, but I don't know if that's true for most wells. I also have a Hach alkalinity test kit. Amazon doesn't carry it, but you can get this one from the Hach website.

If your budget is constrained, you can get pretty good results from a less expensive kit, like this one. Not as accurate or consistent as the Hack kits, but probably OK to get in the ballpark.

Not a bad idea to get a TDS meter. They're not very expensive. However, TDS is not directly correlated to the hardness and alkalinity levels. For example, the hardness of our well water is around 180 ppm and the alkalinity is about 150 ppm. The TDS is usually from 120-140 ppm, even after all the hardness has been taken out by our cation softener (it replaces carbonate ions with salt ions.)

^^^^^ Excellent advice above from Dick Green (Peppersass).

Some comments FWIW...

For these drop kit tests, the terms 'KH', "carbonate hardness", and "temporary hardness" are all commonly used as a synonym for alkalinity. They all simply measure the acid buffering capacity of the water. In natural water these terms often amount to the same thing. The Hach test uses the most proper term here - alkalinity. (Hach makes high quality tests and also provides excellent, chemically literate documentation for them.)

If you have a KH and a GH measure in equivalent units (like mg/L CaCO3 equivalent) your actual 'temporary hardness' or 'carbonate hardness' (hardness that may precipitate as carbonate scale) is equal to whichever is the lower of those two measures. In natural water KH is almost always lower than GH, but in conventionally softened water it's usually the GH that is lower. To do a reasonable scale estimate use both numbers and refer, as Dick suggested, to the bible - Jim Schulman's Insanely Long Water FAQ.

Also with respect to the CO2 and pH of tap water, it's worth pointing out that municipal water supplies frequently treat the water so as to raise the pH, making the water less corrosive and less likely to leach metals from the plumbing. One method is to treat water with slaked lime, Ca(OH)₂ , which ends up neutralizing carbonic acid and removing CO₂. You can sometimes have water with low alkalinity coming out of the tap with a pH of around 8 or so.

And where Dick said " ... cation softener (it replaces carbonate ions with salt ions.)" I think he intended to say that it replaces each hardness cation (Ca⁺⁺ and Mg⁺⁺) with a two salt cations (either Na⁺ or K⁺ depending on the softener salt you use).

In a conventional softener, often called a strong acid cation (SAC) softener, the hardness measure goes way down but the alkalinity (carbonate and bicarbonate ion) is unchanged. With these, a "TDS meter" (conductivity) measurement does not decrease after softening. It should go up very slightly (because of the better conductivity of the sodium or potassium compared to a chemical equivalent amount of calcium and magnesium).

P.S.
Not really applicable to whole house systems, but worth pointing out, is that many of the cartridge systems on the market are very different from conventional softeners. The BWT bestmax, The Everpure Claris, and the Brita/Mavis Quell ST are all examples of weak acid cation (WAC) softeners, also called hydrogen exchange softeners or decarbonizers. These replace each hardness ion with a pair of protons (H⁺ ion) and have the effect of reducing the alkalinity along with the hardness. They tend to drop the pH and are sometimes buffered so as to reduce that effect. With these the conductivity decreases with the alkalinity and you will expect a small decrease in a TDS meter reading.

Excellent clarifications from someone who knows way more about water than I do!

I would add that there's been some talk about hydrogen exchange softeners reacting with high levels of chloride in the water to reduce pH below recommended levels for espresso machines.

I started with a cation softener, then switched to an Everpure Claris (another H-B member gave me a spare Claris head and I bought the cartridge.) When I heard about the possible low pH levels, I checked and found that the pH of the Claris output water was about 6.5, which was below LM's recommendation for my GS/3 -- despite feeding back enough tap water to bring the hardness level to about 70 ppm.

But we don't have high levels of chloride in our water. At least we didn't 25 years ago when we had the water tested during the house inspection. Nonetheless, the low pH alarmed me and I switched back to the cation softener, which I've used ever since. Soon after, I found out about dissolved CO2 and carbonic acid being common in New England well water, and I suspect that's a better explanation for the low pH of water coming out of the Claris.

Peppersass wrote:Yes! Here in the East, water from wells in rocky areas is likely to contain dissolved CO2 and carbonic acid due to the effect of acid rain on limestone. The carbonic acid inflates pH readings of cold water. The CO2 comes out of solution when the water is heated, which will result in a higher pH reading.

I'm surprised your report doesn't include carbonate hardness. If it's not there, I strong advise you to get a good quality hardness testing kit before selecting a softener. I think the Hach hardness testing kits are the best. This one is good for measuring larger amounts of hardness, which is pretty likely in well water from rocky areas. If you want to measure very small amounts of hardness, such as what you get after using a softener, then you should get this much more expensive kit. Unless you're OCD like me, it's not really necessary, since the less expensive kit can tell you if the hardness has climbed to a level that will produce scale (i.e., the softener cartridge needs to be changed or recharged.)

Note that the level of hardness in well water can vary (it does in our well water), so it's good to check the softener output on a regular basis. Our alkalinity level stays pretty constant, but I don't know if that's true for most wells. I also have a Hach alkalinity test kit. Amazon doesn't carry it, but you can get this one from the Hach website.

If your budget is constrained, you can get pretty good results from a less expensive kit, like this one. Not as accurate or consistent as the Hack kits, but probably OK to get in the ballpark.

Not a bad idea to get a TDS meter. They're not very expensive. However, TDS is not directly correlated to the hardness and alkalinity levels. For example, the hardness of our well water is around 180 ppm and the alkalinity is about 150 ppm. The TDS is usually from 120-140 ppm, even after all the hardness has been taken out by our cation softener (it replaces carbonate ions with salt ions.)

the HACH test kit you suggested, is that more accurate than this HACH test strip?

https://www.amazon.com/Hach-2745250-Tot ... B008FM7WLU

i may not be the right one to help with your question.. but in my case, our tap is about 25 drops using the API GH test kit, so we have a Kenmore water softener that is set at 25 to match. then from there, my tap is now 3 drops.

i think you would want it as low as possible for the type of machine you use. i've been running this setup with my breville for past 5yrs and no build up.