This took me a while - and a lot of 'cupping' waters - to figure out, so in case anyone else experiences this:
Sometimes my water would have a plasticky vinyl taste. Sometimes. I occasionally taste the water coming out of the HX and boilers to assure myself that the water from the espresso machines tastes identical to the water going into the machines (when both are tasted at room temperature). I'd drain the boilers and refill and everything would be fine ... for a few weeks, or a few months, or ...
What didn't work:
- changing from plastic water storage jugs to glass storage jugs.
- reverse osmosis
- activated carbon filter
- ceramic filter
- Brita filter
It took a while, but eventually Chloramine (and its decomposition/reactions) was identified as the culprit.
What kind-of worked:
- more severe distillation methods - letting the water boil open for 20 minutes before starting distillation, and discarding the first and last 500ml of distilled water produced;
- letting the distilled water sit open for two weeks inside, or a few days outside. (This is called "sun water" - but that's just a term. What is really happening is CO2 in the air is diffusing into the water. The Chloramine eventually breaks down.)
What actually worked:
- a 'catalytic' activated carbon filter that removes Chloramine (and Chlorine). As an aside, these filters flow very slowly.
The root issue was that my otherwise-awesome municipal water can be sterilized with both/either Chlorine and Chloramine - with the mix between the two varying as needed.
A good reference: https://www.ncbi.nlm.nih.gov/books/NBK234590/#ddd00031
Water analysis, treatment, and mineral recipes for optimum taste and equipment health.
- Supporter ♡
What I'm interested in is my worst espresso being fantastic - James Hoffmann
- Team HB
We've got a filtration system here for cooking and drinking water and a supply that uses chloramine. The 10" Pentek cartridges that reduce chloramine are slow, as you note. We limit that under-sink setup to ~1/2 gallon a minute.