Golf's bizarre water bottle rule that could cost you a penalty out on the course

It's a pretty natural given that most of us probably don't drink enough water out on the course – especially when there are drinks carts and ice-cold beers involved.

But for those of us who do endeavour to stay hydrated throughout a round of golf, what you might not know is that the simple act of taking a drink at the wrong time could, in certain circumstances, cost you big time.

What we're rather cryptically talking about is a little-known, rather bizarre rule that governs the use of water bottles on the putting green. More specifically it governs the act of putting your bottle down on said green, which according to the rules is an action that could constitute a two-stroke penalty.

Why? Because theoretically, water in a clear bottle could be used as a makeshift level, giving you a more accurate read of the lie of the green than what's allowed.

This is confirmed in USGA rule 14-3, which governs the use of artificial devices and equipment used in an unusual manner to assist the player. In decision 12.5, the USGA specifically states: 

“You cannot place a water bottle on a green and use it as a level to determine how a putt will break.”

There is, of course, some room for creative interpretation here. Can you put a water bottle down on a different part of the green? Can you simply claim that you weren't intending to use it as a level? Does the rule apply to empty water bottles or those that aren't see-through?

Naturally, all of this goes without saying that you'd have to be playing with a monumental stickler for the rules for someone to call this out in casual play.

And while I'm not sure I've ever been so desperate for a drink that I've taken my water bottle out on the green to putt with anyway, some definitely do. Japanese tour pro Ryo Hisatsune famously takes a sip of water before every shot, including his putts (note that his Caddy is careful not to place the bottle on the ground).

All in all, it's one of golf's many odd quirks that's well worth bearing in mind should you ever head out in competition play on a particularly hot day. And it's safe to say we'll be leaving our bottles firmly on the fringe just in case.