How to Determine the Yield of a Water Well

Testing your water well yield is the first step in determining quality of your water source.

Contaminants can be treated and filtered but it matters little if your well runs dry.  The EPA recommends annual testing to maintain the safety of your drinking water supply, but we rarely think about the actual amount of water available or your well yield.

With climate change and environmental challenges like the prolonged drought currently being felt in the Western US, knowing the maximum safe yield of your well is important. The maximum safe yield represents your well’s dependable and continuous output during periods of sustained drought. You need to have an understanding of your well yield to ensure that it can sustain you and your family during demanding times. Your well yield may be found in the well log compiled when the well was drilled. Some communities require any sale of a home to have documentation of well yield included in the disclosure process.

What is a Well Yield Test?

A yield test consists of determining the balance between the maximum amount of water that can be pumped and the amount of recharge back into the well from the surrounding ground water. Testing is done by continuously pumping water from the well for an extended period. During pumping measurements are made of the amount of water flowing from the well and the amount the water level is lowered in the well itself. This is known as the well’s drawdown.

Equilibrium is achieved when the drawdown remains stable for a given discharge rate. Once equilibrium is achieved, less pumping should result in lower drawdown rates. Professionals rely on this pump yield test to place the well pump at the correct depth in the borehole. The standard is to maintain a water level of 25 feet above the top of the submersible pump. This allows for a comfortable margin of safety during drought conditions and works to keep the pump motor cool and running properly during use. Water pressure in your home is not entirely dependent upon overall yield. Proper sizing of the pump, pressure tank and lines can increase water pressure even in instances of lower yield.

Your city or town may have minimum codes for well yield. If you have any questions, contact your local water or health department or give your water technician at Skillings & Sons a call.

Conducting a Yield Test

Testing for safe yield is a complicated process best conducted by a state-certified well water professional such as Skilling & Sons. Our team has the necessary equipment to complete the test and the knowledge to make any plumbing adjustments necessary depending upon the test’s results.

In a new well, testing can be conducted immediately after drilling but before the well is connected to the home.  For an existing home, your contractor will create an artificial demand on the home’s system to keep the pump continuously running and will then measure the water discharge during pumping.

In the event a problem is diagnosed, there are options for increasing yield. Hydrofracking is a process that uses water pumped at high pressure into your well to open new fractures in the bedrock allowing greater access to ground water supplies. Contact Skillings & Sons. Our state-certified well water professionals can walk you through the testing process and consult with you on the options available for improving your well yield.