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I mentioned this about six months ago.
You don’t even need to rinse them, most have the plastic caps so you can turn them upside down to get the soap almost entirely out to wash with, then just fill em with water.
I use a black magic marker to write a big S on the front so I know it’s soapy water, not potable water.
Not really necessary, because my general rule in re-using plastic bottles is “If it came with food in it, it’s ok to use for potable water. Anything else is utility water”.