milpitas water supply is same as SF.
refer to this report
http://www.ci.milpitas.ca.gov/_pdfs/pw_water_quality_report.pdf
look under SFPUC column. I did not see chloramines. Also, avg TDS of tap water it says is 81.
FWIW, I have 4 stage, but I only installed 1 carbon and 1 sediment + RODI membrane and DI unit. I think I have one or two canisters with no media, and I replace the carbon and sediment every 1.5+ years and at that time, the output tds is 1.