[Myka]

After testing 1580 ppm from the RO, did you immediately test the tap water at 170 ppm? I'm just wondering if the meter is kaput.

To figure out where the high TDS is coming from check the tap water, then check the water immediately after the sediment filter (disconnect the hose between the sediment and the carbon and test the water that comes out), then test immediately after the carbon block, then test immediately after the RO (be careful to check the proper line, check the one that goes to the DI resin), then check after the DI resin. Collect the water in a clean shot glass for testing. By testing each stage you will find out where the contamination is coming from. If everything tests ok then it is probably your storage container.