I always run one, it's not really resistant, I've hit small puddles and big puddles and had the bike splutter from water, you guys will find out that the only gain is to stop the finer dust from getting to the filter, they are awesome and cut down/ nearly totally cut down the need to clean your air filter. But I keep seeing water mentioned and it couldn't be further away from what the filter actually does that's all guys, I recommend them for everyone.