cleaning the fresh water tank

Welcome to the forum. Since I have no idea of your tank's condition, I can't say for certain.

Have you sanitized the tank after dewinterizing? If not, then for a 30 gallon tank, you will need plain (no cleaning additives) bleach. Recommendations vary but 3/4 cup for a 30 gallon tank should be fine. Fill the tank part way, add the bleach diluted with water, and finish filling the tank. Run the faucets (don't forget outside shower/spray port) until you smell bleach. Shut the faucets off and top off the tank. Then let it sit for at least 8 hours.

Then drain the tank and use the low point drains to drain the bleach-water out of the system. Close the valves and fill the tank with fresh water. Flush all the lines with the fresh water. You may need to drain and repeat. Then the tank and lines will be sanitized. Once this is done, if there is still a taste of chlorine, you could use either vinegar or (my preference) baking soda to help remove any residual taste. It doesn't take much.