While searching for the answer to your question, I started to realize that I should have done more homework before jumping in. Although the product description doesn’t say it, many of the questions and answers on Amazon indicate that this device is really intended to be used with a reverse osmosis unit, which brings the TDS down prior to deionizing. If you don’t do this, and your tap water has high TDS, you will burn through the DI cartridges very quickly. Here’s a question and answer from the seller, along these lines:
I've tried this one and for me it doesn't work well. Seems to leave a residue that's worse then not using it. I'd discourage anyone from buying.
No, unfortunately don’t know the TDS of our local tap water. Tried to google it, hoping someone may have reported it, but can’t seem to find it for my town. I know some parts of Oahu have very hard water, though, as my previous home I would get white crusty build up on my shower heads and I destroyed a couple keurigs with hard tap water (thought Britta would filter out TDS, but apparently it doesn’t). In my new home, it doesn’t seem nearly as bad, but it’s probably still on the hard side.
Looking at that confirms my question about the lack of other filters.
