Towels hold a lot of moisture
Because towels are thick and absorbent, a crowded load can wash and rinse poorly and then take longer to dry. Persistent dampness makes musty odor more likely.
Check detergent and load size
Use the detergent dose appropriate for the product, washer, load and soil. Too much product can leave residue, while too little may not remove body soils effectively. Avoid packing the drum with heavy wet towels.
Move and dry them promptly
Do not leave washed towels sitting wet in the machine. Dry completely using the care-label-approved method before folding or storing.
When the washer may be involved
If towels and other loads all develop the same odor, clean the washer according to the manufacturer instructions and inspect dispensers or seals where relevant.
Garment care labels, appliance manuals and laundry-product directions can be more specific than a general guide. Use them when they set a tighter limit.