How Waterproof Are MyTopo Maps?
That said, the paper is “coated” and if you rub it, the ink can come off. It's intended to be waterproof enough that if it's raining or snowing, or is spilled on, the liquid will come off with a quick shake of the map.
And, according to our supplier, environmental regulations have resulted in some changes to the formulas used to make waterproof paper/ink, which may mean that our maps are not quite as tough as they were in previous decades. But, the trade-off is that the chemicals used in the inks and paper are less harmful.
We recommend keeping the map clear from dirt or sand that can act as an abrasive, even keeping it in a protective case. With some care, your map should last you for years. And, remember, if it gets wet, just shake it off and it should be fine.
Don't believe us? Check out this video: