Rubber hose broken. Cut in two and join pieces with a metal hose-mender.
Rubber on hose cracked. Rejuvenate hose by painting it with liquid neoprene rubber or plastic rubber.
Vinyl hose broken. Cut in two and join pieces with a plastic hose-mender (different from a rubber hose-mender). Tubes of mender are slipped into opposite pieces of hose and held in place by metal rings on the outside of the hose.
Hose leaks at coupling. If a new washer doesn't help, replace entire coupling.