Do you have Axion Hymer Carado. Someone borrowed my RV and use the sink for fresh water cold winter so it triggers the safety valve to divert water to the ground to prevent pipe damage, This happened to me last time and the dealer said that there a flip switch to drain the water to holding tank I forget how it looks but it should be under the bed close to toiler. I have an 2017 Axion Hymer carado the basic model