F.A.Q Flow Tests


Frequently Asked Questions

Flow Tests

Q: What is flow a test?

A flow test is a test performed to determine the maximum rate at which a borehole or well fills with water under typical conditions.

It helps specify nearly all the parts of a system design.

Q: Why do I need to know this?

You need to know this because the maximum rate at which your borehole or well fills, is equal to the amount of water which you can draw in any period of time. For example, if your well or bore hole is filling at a rate of 24 tonnes per day or 1 tonne per hour, then the maximum rate at which you can remove/pump the water is also 1 tonne per hour.

Attempts to draw more than 1 tonne per hour will result in you pumping the borehole or well dry.
This needs to be avoided as damage can occur to your pump. Whilst many of today's pumps come with dry run protection to avoid potential damage in the event of such a scenario, pumps nevertheless don't like it and are not designed to pump air.
Continuous 'dry runs' may eventually lead your pump to fail despite dry run protection electronics being installed.

This mainly happens because the pump relies on the water to cool the pump.

If your well or borehole is producing 24 tonnes per day, and you use only 20 tonnes per day, then all seems fine because your daily maximum yield is less than your requirements.
BUT, if you have a peak usage time say mid morning, where you need 3 tonnes in one hour, you're going to run into trouble because your bore hole can only produce 1 per hour.
The solution is simple - water storage tank, you can view our storage FAQs page for more information about that.

Q: How is a flow test conducted?

We need to know how quickly, or how slowly your borehole or well takes in water, its yield, the rate at which water flows into it.
Seasonal changes may be expected of course. Prolonged dry periods may lower your borehole or well's water level.

Natural aquifers feeding into your borehole or well may slow down. Equally, during wet periods, the water line may come further up and your borehole or well may have an increased yield.

By performing a single flow test, we are able to get idea of the sort of volumes generated on. This is generally good enough for most situations and does not usually require a re-test at other times.

Firstly we attempt to pump the bore hole or well dry to empty it. Then using a combination of a split timer, pump specs, water meter and an electronic dip line, we measure the water level's increase against some fixed time interval. This test generally takes the better part of a whole day.
During the test we also pump measured volumes of water in very specific time intervals and throttle the pump back accordingly until we are able to pump water at the same rate as the well or bore hole is filling. Using a combination of a timer, throttled pump, flow meter and electronic dip meter, we can then state that this well or bore hole yields volumes equal to ....ltrs per hours or per day.

This a very accurate means of determining a flow rate and from this calculation, the entire system will be run. We are unable to go by a given flow test and guarentee accuracy we must perform the test ourselves. Being off by 10 ltrs a minute can have a major impact on a system especially a filtration system.