Water is part of the four classic elements, and the symbol can be seen in old alchemy scripts. As you may have noticed, the upside down triangle has a feminine form, the shape of the womb, and this link ties with the symbols feminine energy which connects to aspects of the Goddess.
As you may have guessed, due to the use of "Holy Water", water is typically related to healing and purification. In fact, Holy Water tends to have salt added, which exaggerates the purification factor. In many Wiccan covens, salted holy water is used to consecrate the circle and all the spiritual tools within it
Many cultures feature water spirits as part of their folklore and mythology. To the Greeks, a water spirit known as a naiad often presided over a spring or stream. The Romans had a similar entity found in the Camenae.
Water can be used in rituals involving love and fluid emotions, at the same time as allowing a current to carry away anything negative that you wish to be rid of.