Thanks so much everybody! Very helpful to learn and understand all of this, I appreciate it!

As for my water situation, out of the hot water wand, I pulled a glass of water and let it cool to room temp. I had gotten around 225-250ppm from the steam boiler after a year of use and never draining it, and very infrequently using the hot water steam wand (but steaming regularily). This is with very soft portland water running through a homeland water filter from Clive.

After emptying it out, my PPM reading was only 35ppm from the steam boiler now, matching 35ppm from the brewhead group. For reference, my tap water is 19ppm right out of the faucet. I can only assume, even after filtration, that having the water heated in the boilers introduces more mineral content? In any case, I did see a significant reduction in TDS after draining the boiler as best as I could.

dsc106 wrote:I can only assume, even after filtration, that having the water heated in the boilers introduces more mineral content?

No - what is happening is that every time you steam, you are removing pure water and leaving minerals behind, and it will become more and more concentrated over time. Eventually it may get concentrated enough that it will drop scale in the boiler. Just either drain the boiler periodically or, in your soft water situation routinely pull some water out of the water tap before each steaming session. You can keep an eye on it with your TDS meter - - as long as it routinely reads something below 60 ppm or so after cooling to 25C I think you're doing fine with your draining strategy.

The water out of the group (brew boiler) in your situation should read roughly the same TDS as the water going into the machine, provided you read both at the exact same temperature and your group is nice and clean.

Right! So I've had the machine for a year, always on the homeland water filter, but basically never using the hot water wand - just very very rarely. It wasn't until recently that I discovered yellow tinted water coming from the steam boiler, and got a room temp TDS reading of ~260ppm. Back down to 35ppm now.

Would that duration of time (who knows how long it took to reach ~260ppm, maybe we could estimate +20ppm/month) not cause any damage/scale? Did I save the day in time, or would a few months at ~260ppm (in the steam boiler only - brew boiler has always been good) be enough to accelerate my need for a future descale? Or is more like, a descale every ~5 years or so is required anyway, and this will barely impact so long as I am "good" now about emptying the boiler a bit via the hot water wand every so often?

dsc106 wrote:Would that duration of time (who knows how long it took to reach ~260ppm, maybe we could estimate +20ppm/month) not cause any damage/scale? Did I save the day in time, or would a few months at ~260ppm (in the steam boiler only - brew boiler has always been good) be enough to accelerate my need for a future descale? Or is more like, a descale every ~5 years or so is required anyway, and this will barely impact so long as I am "good" now about emptying the boiler a bit via the hot water wand every so often?

I think you should be fine here, and no need to descale. Probably never because you are on Portland water with a conventional softener to boot. As long as you routinely use the hot water wand to offset each use of your steam wand, your very soft water will tend to slowly dissolve any limescale that may have built up. One quick-check for problem scale in a steam boiler is to pull the level sensor probe and see if there is any scale deposit on that. Another is to remove the vacuum breaker and look in the boiler with an endoscope. But I don't think you need to do that.