Watter Purification

It is, of course, preferable to have Ganga jal [water from Ganga] for puja, but
that is not always possible or practical.  So, if Ganga jal is unavailable, one
may use this mantra to purify whatever water one has.  It is considered
improper, however, to use water collected from the bathroom for sacred purposes.

Gange cha Yamune chaiva Godavari Saraswati,
Narmade Sindhu Kaveri jalesmin sannidhim kuru

In this water I invoke the presence of holy waters from the rivers Ganga, Yamuna, Godavari, Saraswati, Narmada, Sindhu, and Kaveri