Rain gauge watering can/pump ass.

Lawns need about 25 to 38 mm (0.98 to 1.5″) of water per week. This rain gauge tells you how many millimetres of rain per square meter fell. One millimetre corresponds to 1 L (1.76 UK Pints) of water per square meter (10.76 square feet). Make a note of the amount of rain a week, so that you can decide whether you need to watering your garden. Bring the rain gauge indoors during the winter months.