Nitrate strip tests

In my attempt to get my nitrates as low as possible I have been in search of the best water without adding an RO system just yet.

When I use a strip to test different water (Tetra easy strip) testing distilled water, tap water, spring water the test strip is never white always shows some nitrate level. The strips are not out of code :)

Will the test strips ever show white when testing water? Does RO water test white?

Thank you, Joe.