In Sonoma County in an average year we receive about 30 inches (76 cm) of rainfall.
In the winter flood of 1986, “[a]t Calistoga recorded 29 inches (740 mm) of rain in 10 days, creating a once-in-a-thousand-year rainfall event” according to this wikipedia article.
Worldwide the highest recorded rainfall rate I could find was 1.50 inches (3.8 cm) in one minute in Barot, Guadeloupe on November 26, 1970.
Rainfall is measured by its depth in inches or centimeters. When a weather observer reports a 1 inch rainfall this means some form of rain gauge collected 1 inch of water. The U.S. National Weather Service relies on a gauge that is 8 inches (20.32 cm) in diameter.
The water falling into the gauge drops through a funnel into a graduated cylinder. A weather observer reads the amount twice each day.
The standard 8-inch gauge collects a precise volume of water for each 0.01 inches of rainfall. This volume is simply the area of the cylinder times the depth of rainfall:
volume, 
For a 0.01 inch rainfall:
= 3.14 / 4 * 8^2 * 0.01
= 0.503 cubic inches [cu in]
= 8.24 cubic centimeters [cc]
= 8.24 milliliters [ml]
The tipping bucket rain gauge tips when it contains this much water. And 8.24 cc’s of water weighs 8.24 grams.
Average Year in Sonoma County
So, each year a standard rain gauge will collect a total volume:
Vannual
= 3.14 / 4 * 8^2 * 30
= 1,508 cubic inches [cu in]
= 24,711 cubic centimeters [cc] [ml]
= 24.7 liters [l]
while collecting Sonoma County’s typical 30 inches of rainfall. Since the bucket tips once for each 0.01 inches of rain, then over the year the bucket will tip = 30/0.01 = 3000 times. From an engineering standpoint, 3000 motions per year is pretty light duty.
What About a Really Heavy Rainfall?
Given that the heaviest recorded rainfall was 1.50 inches in 1 minute, how fast would our tipping bucket actually tip? We know the bucket is designed to tip once for each 0.01 inches, so in the case of 1.50 inches, the bucket will tip 150 times in 1 minute = 150 / 60 = 2.5 tips per second. This means each tip must take less than 1 / 2.5 = 0.4 seconds. We will need to keep this figure in mind as we design the actual bucket.
It is important to characterize any instrument well enough to detect when it is operating outside its innate limits. For the tipping bucket we need to know when to raise a “TILT” warning if the rain ever comes down too fast for the mechanism to keep up.