Yes, hiking boots can be washed in the washing machine but it is not recommended because it can damage your boots. The detergent and soap contain additives that can be harmful to the materials. Also, washing your boots excessively may damage the waterproof membrane and your boots will lose the waterproofing ability. Some fabrics like cotton, polyester, and nylon can be safely machine washed, but animal-based fabrics such as suede and some other similar materials are not recommended to machine wash. If you must have to wash them in the machine, use a front-loading machine and not the top-loading because the agitators in the top-loading machine will completely damage your boots.
Gather the essentials
Before putting your boots in the machine, make sure you have essential cleaning supplies. You may need liquid detergent (never use soap), a cleaning brush, a large laundry mesh bag, and a clean microfiber cloth.
Remove the laces
To speed up the washing process, remove the laces and insoles from your boots. They can be washed separately.
Remove any large debris
Remove any large visible debris, mud, or dirt by hand. You can also use a toothbrush to deep clean the seams. Use the brush to scrub the rest of the boot including the outsole.
Clean the inside and upper
Use the microfiber cloth to clean the inside. There may be a lot of dust and debris. Use the same cloth to further clean the upper.
Put your boots in the washing machine
At this stage, you have done all the handwashing and your boots may already be clean. Now it’s time to clean your boots a little further. Stuff some cloth at the toe area so that the shoe maintains its shape throughout the wash.
Put your shoes in the laundry bag (a pillowcase also works), tie off the bag, and place them in the front-loading washing machine. Add approx. 4 tablespoons of laundry detergent. Set the cycle to as gentle as possible because you don’t want to damage your boots. You may also put a few towels to balance help balance the load. Start the machine and come back after an hour or so, remove the boots and let them dry. Never put boots in the dryer, always air dry them.