The most accurate check that can be made to determine the yield of a well is to make a pump test. Bailing is the lowest cost way of making a pumping or well test and is adequate to test a well that is to be pumped intermittently at low rates such as for a domestic supply.
A somewhat more expensive way is to install a temporary test pump with a capacity of 1 1/2 times the capacity of the desired water system. Obtain the pumping rate by measuring the time it takes to fill a bucket of known volume.
Measure the depth to water before, during, and after pumping to get the drawdown. A wetted tape is simple and accurate. Wipe the tape dry, and coat it with carpenter's chalk. Lower the weighted tape into the well, and subtract the wetted reading from the reading at the top of the well casing.
Results of the pump test include:
The water volume pumped per minute or hour.
The depth to the pumping level over a period of time at one or more constant pumping rates.
The water level recovery after pumping is stopped.
The length of time the well is pumped at each rate during the test procedure.