I still vote to wash it and see, but call the fabric shop first and see if they will replace/reimburse if the smell doesn't come out. Rain water has a whole different reaction than tap water. Wash with whatever detergent with vinegar in the softner dispenser. My machine has an option for a double rinse and I use this on bedding and fabrics with a vinegar rinse. It helps get all the detergent out, which is afterall, a chemical also. Diane/Wyoming