How many bottles of eye wash solution should I keep on hand?
More than one, preferably three or four. The more you can keep on hand, the better. If you're in an emergency situation, and someone needs their eye flushed you'll want to have enough solution to be able to properly cleanse their eyes. You can use water from a faucet, but that is not advised and is generally considered a last resort solution. The water faucet can contain contaminants and chemicals that could make the problem worse.