One of the responsibilities of levites is to help kohanim prepare to do the priestly blessing.  Appropriate signage for sinks is illustrated here and also available as a PDF file by right clicking here.

See also:

• Spilled Some Salt?  Call OSHA
• Fasting For Yom Kippur (from a Medical Perspective)
• Learning from the Bar / Bat Mitzvah Experience
• A Jewish Approach to Halloween