Let the diapers soak 5 - 10 minutes in hot water, then dip the scrub brush in a hot water soapy mixture and scrub on both sides of the fleece. (tinytush.com)
Wash these with a mild soapy mixture or with just hot water if they are not visibly dirty. (caringpets.org)
Use hot water and a diluted soapy mixture to scrub the insides with a scrubber on a long handle; a water bottle brush is a good solution. (caringpets.org)