Here's a picture of one of those wooden water mains.
Wooden pipes were put under the ground to carry
water to people's homes. These pipes were made of cedar logs, about
10 feet long and a foot thick. A large hole was bored through the
center of each log.
Before the water was turned on, two miles of bored-out
logs were laid end to end under the ground.
This water system had several problems, however. First, it only served
a small part of the city. Second, water flowed through the pipes with
the help of gravity. The further away from the waterworks you got,
the less water pressure you had. Third, fish would often get into
the pipes and clog people's faucets. (How would you like to take a
bath with a tubful of fish? Especially dead ones?)