I am (probably) upgrading to plumbed in La Spaziale mini Vivaldi and I'm looking at filtering/softening my water using either BWT or Homeland filters.

Using Varify brand test strips my parameters appear to be:
Total Hardness 1.5 gpg/25 ppm CaCO3
Total chlorine 0.5
Alkalinity 0-20 (the color is between the 0 and the next choice 20
pH 6.2

I am surprised my water isn't harder as there is significant residue inside my now dead BDB. I was changing o-rings as leaks occurred but not regularly/annually.

I am looking at filtering using either BWT or Homeland HCWS filters. Any thoughts? TIA!

Based on those numbers it doesn't look like you need any softening at all. I would advise trying a better test kit and/or contacting your water authority for more numbers.

Colorado Springs water authority does publish some good information here: https://www.csu.org/Documents/WaterQual ... ySheet.pdf. The good news from that report is that all those sources are low in chloride ion, which can be a troublesome issue (when chloride is high you may need to resort to RO treatment.) Two of the five sources do put out water that is hard enough that you would want to use softening, much harder than you measured, and it might be useful to learn if they provide water to your location.

To measure yourself with an inexpensive and easy to use kit you can pick up an API GH & KH test kit from a local aquarium store or buy one online. The kit comes with a 5 ml sample tube, but you can get better precision with your soft water by finding a small vial or container that holds a 10 ml sample. If you use that kit with a 10 ml sample, then each drop corresponds to 8.9 ppm as CaCO3. GH is total hardness and KH is alkalinity.

If you don't appear to need softening, you could opt for the Homeland and it would do no harm, and if your water utility did temporarily switch to a hard water source it would effectively soften it without reducing the alkalinity nor acidifying the water. But if your water is reliably soft, then you really only need a good particulates and carbon block or charcoal filter (the latter removes chlorine, along with off-tastes and odors.)

ColoPuka wrote:I am surprised my water isn't harder as there is significant residue inside my now dead BDB. I was changing o-rings as leaks occurred but not regularly/annually.

If you are looking at accumulations of residue around leaking seals, fittings, and valves then that may not be limescale -- may just be normal dry residue that you would get even with soft water.