Water timer

A water timer is an electromechanical device that, when placed on a water line, increases or decreases the water flow through the use of an embedded (solenoid) valve. It is used in conjunction with irrigation sprinklers to form an automated or non-automated sprinkler system, capable of administering precise amounts of water, at a regular basis.

An alternative to a water timer to administer precise amounts of water at a regular basis, is to precisely calculate the needed waterflow and arrange a system composed by a Time switch and an electric pump that. The electric pump is to be arranged to be turned on and off at regular intervals by the time switch to administer (fairly) precise and regular water quantities. This approach, used frequently in DIY watering systems, allows financial savings as the water timer can be discarded. For high-end applications however, water timers sometimes allow more flexibility and more options.

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Wikipedia