Re: Water maker Questions
250 ppm is what you are looking for as far as TDS goes. The EPA’s recommended maximum level of TDS in water is 500 ppm. Note, it's not a limit, just a recommendation. The 500 number you saw may have been for Conductivity (proxy for Salinity) which is measure in microSiemens/cm (µS/cm). You want that between 200 and 800 and I think Dessalator claims 250 TDS and 550 Conductivity in their marketing material.
I picked up this kit from Amazon to test it: https://www.amazon.com/gp/product/B077SQTKH4/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
I have no idea how accurate it is, but it gives me reasonable results for tap water, distilled water, Chesapeake Bay water and watermaker water so it appears to be accurate enough.
SM #440 Cara
Deale, MD USA