O-rings should be checked and lubricated regularly, they are more likely to break if they are dry and brittle. Using a food grade (non-toxic) lubricant on your O-rings will keep them watertight for longer. Check carefully for any tears, cracks, or breaks within the rubber that may compromise the seal. If you see any damage, replace them immediately or your tank may not be properly filtered.
Remember that O-rings come in specific sizes that match each filter model, so ensure compatibility with your filter when purchasing replacements.
Find out more information on when you should replace aquarium filter parts.