Upon arrival customer stated dripping noise coming from inside of wall from upstairs hallway bathroom. Attempted to duplicate dripping noise by running faucet, shower, and flushing toilet. No dripping noise. On the way out dripping noise occurred. Crawled in attic to try to locate possible leak. No evident leak. Opened small square under vanity sink to expose piping. Portion that was exposed didn’t have any evidence of leaks. Customer didn’t want to go with further demolition of wall. He will be opening wall in attempt to find leak and contact Huft to get quotes for possible repairs.