top of page

Well Yield Testing

How Healthy Is Your System?

A Well Yield Test is a timed-test to determine how many gallons per minute a well system can produce. During a Well Yield Test, water will be run from the pressure tank and measured in 15 minute intervals for the duration of the test. The last 5-gallon reading is determined to be the “well flow” or “yield” for that well.

What will we be looking for?

  • Is the well pump and pressure tank functioning.

  • Is the well running dry or does it lacks sufficient recuperation.

  • The reserve amount sitting in the well.

  • If the buyers would have to stretch the time between running water: showers, laundry, car washing, dish washer, etc.


Well Flow Rates

While performing a Well Flow Rate, our inspectors provide a complete inspection of the well components. This includes researching any available records located at the local Department of Environmental Health. We inspect the well casing, cap, interior plumbing (distribution), pressure tank, pressure gauge, electrical supply, pressure switch, and all related components. Often there are many different filtration and treatment devices connected to a system. At APECS, Inc., we perform our Well Flow Rate at the first primary source, if possible. This usually is the first bib located near the pressure tank. At this point, the supply is usually a 1 inch line. The flow rate can be reduced drastically if taken anywhere else, basically because the distribution line is generally reduced to ¾ or ½ inch which restricts input volume. In Maryland, Well Flow test can take anywhere for 3–6 hours or more, depending on which county you reside in. Our inspectors are certified through the Maryland Department of Environment Health, and have also been approved for the collection of drinking water and are certified under The Safe Drinking Water Act, and all state regulations and guidelines.

Well Flow Rates vs. Yield Test

Well Flow Rate or a Yield Test which to choose? What are the differences? For most people the testing is related to, or in conjunction with, a Real Estate transaction and their lender or bank is requiring the test to be completed. In most cases, a Well Flow Rate will provide them with the necessary information they are requesting. This includes a thorough inspection of the well and its components, how much water the well produces to the home over a period of time, and will the components, mainly the pump, work properly and sustain a long period of usage. This is measured via a bucket and a stop watch every 15 minutes, recorded and provided to the client and/or lender. This test will also provide an accurate amount of volume, (GPM) gallons per minute, supplied by the well.  We also provide our clients with any available records located at the local Department of Environmental Health. A Yield Test can only be performed by a licensed Master Well Driller. The well is opened at the well casing, a pump is lowered and the water is pumped out, and in short, is measured similar to a Well Flow Rate. By doing this the well will need to be re-chlorinated or disinfected and water samples collected. 

How To Disinfect Your Well Water After A Failed Bacteria Sample

This is a three day process.

  •  Prior to chlorination, draw off enough water for about 24 hours of household use not for drinking, but for flushing the toilet. Bypass any water 

       conditioning equipment.

  • The well cap is removed and the Well is Chlorinated.

  • The garden hose is connected to the outside tap and its placed inside the Well. The water is turned on at the tap and the water then circulates for 2 hours. Water is turned off, the hose is removed and replace the Well cap.

  • The water is ran through each tap throughout the house. The tap is turned off immediately after a strong chlorine smell or milky water is observed. The chlorinated water is to remain in the plumbing system for at least 24 hours.

  • The next day, the water is ran from the outside tap through the garden hose until the chlorine odor has completely disappeared.

  • The removal of chlorinated water from the Well may take 2-3 days. Follow up bacteria sampling is recommended by a certified specialist.

What NOT To Do:

  • Do not run the chlorinated water into your septic system, as it may overload its capacity.

  • Do not use the heavily chlorinated water for bathing, laundering and washing sterling silver. Also, the ice maker should be turned off.

  • If a water treatment system exists, contact your water conditioning company before reconnecting. Well chlorinations introduce high levels of chlorine that could damage your system.



bottom of page