Water testing requirements for yachts can vary based on several factors, including the size of the yacht, its flag state (the country in which it is registered), the type of water system onboard, and the regions where the yacht operates. Here are the general water testing requirements and considerations for yachts:

1. Potable Water Testing:

   – Microbiological Testing: Yachts must regularly test their potable (drinking) water systems for microbial contamination, including coliform bacteria, E. coli, and Legionella.

   – Chemical Testing: It is also common to test for chemical contaminants such as chlorine, heavy metals (like lead and copper), nitrates, and pH levels.

2. Frequency of Testing: The frequency of testing varies by region and flag state. Generally, it is recommended to conduct tests at least once every six months or whenever the yacht enters a new region with different water quality standards.

3. Record-Keeping: Yachts are typically required to maintain records of all water testing results, as well as any maintenance or treatments performed on the water system.