9 CFR §3.10

1. (a)Potable water must be continuously available to the dogs, unless restricted by the attending veterinarian or except as provided in § 3.17(a).
2. (b)If potable water is not continuously available to the cats, it must be offered to the cats as often as necessary to ensure their health and well-being, but not less than twice daily for at least 1 hour each time, unless restricted by the attending veterinarian.
3. (c)Water receptacles must be kept clean and sanitized in accordance with § 3.11(b) and before being used to water a different dog or cat or a different social grouping of dogs or cats.