Pak Tho (Thai: ปากท่อ, pronounced [pàːk tʰɔ̂ː]) is a district (amphoe) in the southern part of Ratchaburi province, western Thailand.

It originates from the fact that the area named Nong Thale ('sea pond') is rather low and thus during raining season was usually flooded.

The crown prince passed along the need to the Royal Irrigation Department (RID) and other agencies.

As of 2018[update] the district has five working reservoirs, a sixth in the planning stage, and Vajiralongkorn has ascended to the throne of Thailand.

The district is now farmed intensively year-round due to the water provided by the five reservoirs built since 1991.