To clean drains without damaging pipes, avoid using harsh chemical drain cleaners as they can corrode or weaken the pipe material. Instead, use safer alternatives like a mixture of baking soda and vinegar or a biodegradable enzyme cleaner. For manual cleaning, use a drain snake or auger to dislodge debris without applying excessive force. Regular maintenance with gentle cleaning methods can help prevent clogs and maintain the integrity of your pipes, ensuring a properly functioning plumbing system without causing damage.