New Lelit Bianca with supplied in-tank filter. Water pH into reservoir 7.0. Cooled water out from machine spout 8.6+. Wassup with that?

TDS by meter is 45 ppm.

I'm testing pH with Aquacheck strips that I use for my spa. Whether or not these strips are best method, the difference is curious.

Martin wrote:New Lelit Bianca with supplied in-tank filter. Water pH into reservoir 7.0. Cooled water out from machine spout 8.6+. Wassup with that?

TDS by meter is 45 ppm.

I'm testing pH with Aquacheck strips that I use for my spa. Whether or not these strips are best method, the difference is curious.

pH can be tricky to measure and interpret, even if you use a calibrated pH meter and are careful about temperature. Especially with low alkalinity water, which you have based on that low conductivity TDS meter reading, the pH is highly dependent on the dissolved CO2 and carbonic acid levels in the water. The two are related (CO2 + H2O ⇋ H2CO3 ⇋ H⁺ + HCO3⁻) so more CO2 means more acidity and lower pH. The water in the reservoir would have CO2 absorbed from the air, and the water in the boilers have lost that CO2 as a result of heating - causing the pH to go up. Let them both sit in an open container for a day or two, measure both at the same temperature, and I suspect they may be comparable.

If the water is from your steam boiler, then as Jeff pointed out, the difference may be primarily due to concentration of minerals, especially bicarbonate ion. You can roughly check that with your TDS meter but be sure to read them both at the exact same temperature. If the water from the boiler has higher TDS readings than the water in the reservoir, that would indicate concentration of minerals, which is the expected effect from drawing steam out of the steam wand. As Jeff points out, if you are using non-scaling water you can manage that by routinely pulling water from the water tap: Using hot water tap to manage steam boiler water concentration

Thanks. Here's my informal summary/takeaway (since "informal" is the best I can manage). Happy to have corrections and caveats.

My household ppm is in a favorable range. Water out of the Bianca through the Lelit-supplied softener/filter drops about 5-7 ppm and likely removes some stuff I don't know about and/or not measuring. This info is actionable by continuing and increasing my practice of using water to warm cups and purge steam, and following recommended maintenance.