What is the primary function of overflow drains in plumbing systems?

The primary function of overflow drains in plumbing systems is to prevent overflow from fixtures. By providing an alternative path for excess water, overflow drains help to manage situations where a fixture, such as a sink or bathtub, may become filled beyond its intended capacity. This is crucial for safeguarding against water damage, as excessive water can spill onto surrounding areas, potentially leading to structural damage, mold growth, or other issues.

In practical application, overflow drains are typically located at a height that is just below the normal water level for the fixture. When water rises to this point, it flows into the overflow drain, ensuring that the fixture does not overflow onto the floor. This design is integral to maintaining safety and functionality within plumbing systems, particularly in residential and commercial settings where water use is frequent.

The other options, while they describe important aspects of plumbing and drainage systems, do not pertain directly to the specific purpose of overflow drains. For example, preventing clogs is related to proper pipe sizing and maintenance, while preventing water waste involves effective usage and recycling of water but does not address overflow control. Likewise, maintaining water pressure is about the distribution and supply of water rather than managing excess water in a fixture.