RE-ASSESSING THE PERFORMANCE OF THE BUCKET PUMP - A SIMPLE WATER LIFTING DEVICE FOR SMALL RURAL VILLAGES By Dr. Costantino Faillace

Borehole Yield Test

During the 1997 pump installation program, a number of borehole
yield tests were carried out by using a light stainless steel 5
liter capacity cylinder . The bailer tests
generally lasted 30 minutes and were carried out jointly with the
villagers. Water was withdrawn manually by a sustained,
coordinated action using, the properly designed cylinder and
nylon rope. The drop in water level was measured several times in
the course of the draw-down test, generally after removing 10
consecutive buckets. The water level recovery test started soon
after bailing stopped and was carried out for 30 minutes with
readings every 2 minute.

From the data collected it is possible to establish the hydraulic
conditions of the well and decide on the most appropriate length
of the wire rope.

From the limited number of bailer tests carried out, a first
rough estimate of the amount of water that can be withdrawn from
boreholes under different hydraulic conditions is outlined below.

1. Poor yielding boreholes with water levels between 20 and 30 ft
can supply 150-200 liters per hour.

2. Boreholes having good yields and water levels around 30ft may
supply 300-400 liters of water per hour during sustained water
withdrawal.

3. High yielding boreholes with water levels around 15 ft may
supply up to 800 liters of water per hour.

The above assessments refer to bailer tests carried out under
sustained water withdrawal. During the normal bailing operated by
the villagers, it is expected that the amount of water delivered
by the cylinder will be 10-15% less than the indicated values.