Residential Yield Test



Why should you test your home borehole?


There a few main reasons for conducting a borehole yield test:

  1. To determine the sustainability of your borehole’s water supply.
  2. To ensure high levels of efficiency and cost effectiveness related to cost per kilolitre.
  3. To ensure the longevity of your borehole equipment.


The main variants effecting the determination of your borehole’s sustainable yield:

  1. Depth
  2. Static Water Level
  3. Test pump capacity and capabilities
  4. Water level movement during testing


To ensure that your yield test was done correctly a qualified and experienced technician is required.


Types of residential yield tests:

You must ask yourself why you are testing your borehole. If you are conducting a yield test to simply determine the maximum yield of your borehole then a Maximum yield test is enough. However, if you want to ensure that the correct equipment is installed and that your borehole aquifer will not be over utilized then you need a sustainable yield estimation. The test we do for these purposes on residential properties is called an Extended Step Test.


Maximum Yield Test (Constant Head Test)

The process wherein a dedicated yield test pump is installed in a borehole to drawdown the static water level to full depth and keep it there for the duration of the yield test. Whilst the water level is kept constant a maximum yield is determined using ultrasonic flow meters and flow control.


Extended Step Test (Variable Flow Test)

The process wherein a dedicated test pump is installed in a borehole and through the use of an ultrasonic flow meter and electronic water level logging device the extraction rate is gradually increased over 30-minute intervals whilst the water level movement is monitored. This process is continued until the rate at which the water level drawdown exceeds the capacity of the borehole. After which that step is extended for a period. Once the required amount of time has elapsed a recovery rate test is conducted wherein the pump is turned off and the recharge rate of the borehole is calculated using the movement of the water level back to its original level.