I soak them in bleach water and then blast them with a hose. I used to use the washing machine, which worked for the polyester socks I started out with. I switched to polypropylene socks, as they are more durable. The washer wouldn't get them clean anymore, so I switched to a bleach-soak and hose method and it gets them looking like new every time.
Bleach and hosing is too much work imo. My washing machines do a great job. My socks are double socks, 50 micron in a 100 or the other way around I forget now.
I have a 2 gallon bucket that has a 50/50 Bleach solution in it. Pull the sock every morning and throw it in their. The I put a clean sock on. On sunday the Bleach bucket gets dumped into the washer and run through with 2 rinse cycles. When they come out they go into a Prime solution bucket that sits next to the bleach one. I have 7 Socks, so I put a clean sock on every morning.
Might be overkill. But it takes me about 5 minutes to do as my Coffee is brewing.