We all sanitize fresh water tank and lines of the RV yearly, why not our hoses too I have.
I sanitized my hoses about 2 years ago and it made a difference in taste of the water.
I used about 3/4 cup bleach to around 4 gals. water (yes strong mix) in a 5 gal. bucket, to get the water to fill the hose completely is to lower hose into bucket starting at one end and keeping hose level in bottom of bucket until all of the hose is in. How long is your call, but mine was around an hour, my hoses were around 5 years old at the time.