From Longman Dictionary of Contemporary Englishtest the water/waterstest the water/watersTRY something TO SEE IF IT IS GOODto check people’s reaction to a plan before you decide to use it The government is clearly testing the water, to gauge the country’s reactions to their proposals. → test
Examples from the Corpus
test the water/waters• Tara VanDerveer, the deservedly highest paid coach in the Pac-10, is testing the waters.• We have tested the strawberries, we have tested the soil and we have tested the water.• Claudia ran Dana's bath, testing the water carefully.• The authority had coincidentally tested the water for toxins on about the same day as the officer cadets had used it.• One felt her skill - here, one was but testing the water in a musical reservoir of immeasurable depth.• Kaiser is testing the waters in the East Bay.• It is quite easy to test the waters to find if a cruise fits your personality.• He tested the water with his hand, adjusted it, and climbed in. 