Mix 18 ounces of 34% Hydrogen Peroxide in a gallon of water and suck or pump it at each tap/drop line when you untap.
Each gallon of the hydrogen peroxide and water solution can cleanse about 65+ taps. Cap each drop line to close off the system and keep it clean in the off season.
Informative Fact Sheet From University of Vermont
Blog Article by Les Ober from Ohio State University Extension
1 ams.usda.gov, “Hydrogen Peroxide”, 5/29/19