Lightly used kitchen towels can usually be washed with bath towels using warm water, proper detergent, and enough space in the machine. Drying them completely is equally important because damp towels can quickly develop odors and bacteria.
Heavily soiled kitchen towels, especially those used around raw meat, greasy cookware, or large spills, should be washed separately or on a hotter, stronger cycle. This helps prevent contamination from spreading to cleaner towels.
A practical routine is best: wash bathroom towels together, separate heavily contaminated kitchen towels, dry everything thoroughly, and replace any towel that continues to smell or feel unclean.