A test of stainless steel water bottles has been conducted to find the best ones for everyday use. The number of water bottles tested varies, with some reports mentioning 9 bottles, while others claim to have tested 40 over several years or an unspecified number to find the best insulated or leakproof options. The results of these tests have been compiled into lists of the best water bottles, including those suitable for kids and those that are leakproof.