A countdown timer on scrums and kicks at goal will be introduced in January to help speed up the game, says World Rugby.
The 'shot clock' means players will have 90 seconds to take a conversion and a minute for penalties, or the kick will be disallowed.
New rules also state scrums have to be started within 30 seconds and line-outs formed without delay, with penalty kicks to be given for time-wasting.
The rules come into place on 1 January.
A clock for kicks at goal is already in operation in France's Top 14.
World Rugby hopes the changes will improve the flow of the game and reduce the reliance on Television Match Official reviews, which add to stoppages in the action.
Water carriers will also only be permitted to enter the field of play when a try is scored.
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