Temporary Water (Formerly Called 'Casual Water') in the Golf Rules

"Temporary water" is a temporary accumulation of water on the golf course. In other words, a lake is not casual water, but a puddle of rainwater (that will disappear once the sun comes out) is.

Temporary water is not uncommon on golf courses, particularly those that don't drain well, following a steady or heavy rainfall. But it is not a water hazard; under the rules, golfers are entitled to free relief if temporary water interferes with one's stance or one's golf ball rests in the water.

The term "temporary water" was introduced in the 2019 edition of the rule book. Prior to 2019, the term used by the governing bodies was "casual water."

Official Definition of 'Temporary Water' in the Rules

Here is the official definition of temporary water as it appears in the Rules of Golf, as written by the USGA and R&A (this is the abridged definition from the Player's Edition of the rule book):

Any temporary accumulation of water on the surface of the ground (such as puddles from rain or irrigation or an overflow from a body of water) that is not in a penalty area, and can be seen before or after you take a stance (without pressing down excessively with your feet).
It is not enough for the ground to be merely wet, muddy or soft or for the water to be momentarily visible as you step on the ground; an accumulation of water must remain present either before or after your stance is taken.
Special cases:
*Dew and frost are not temporary water.
*Snow and natural ice (other than frost) are either loose impediments or, when on the ground, temporary water, at your option.
*Manufactured ice is an obstruction.

What to Do When You Hit Into Temporary Water

Under the rules of golf, temporary water is classified an abnormal course condition. If a golfer determines his golf ball rests in temporary water, or such a condition interferes with his stance or swing, he is entitled to relief. Rule 16 covers relief from temporary water, and breaks down the course of action depending on where your ball sits on the golf course: in the general area, in a bunker, or on the putting green. In each case, free relief is available.

Rule 16.1 is the specific section in the rule book that goes over what to do in each case. In each case, there is also a diagram in the rule book that illustrates how to find the nearest point of complete relief. So be sure to check out Rule 16.1's text for the specifics of taking free relief due to temporary water.