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Well Flow Rates


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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. The cost of a Well Yield is considerably higher, as much a $1,200.00 to $1,600.00 more, then the cost of performing a Well Flow Test.

Disinfecting A Well

• Remove the well cover. Pour required amount of bleach into the well. (see chart below)

If your well depth is less than 150 feet use 1 qt. of household bleach
If your well is from 151 - 300 feet use 2 qts. of household bleach
If your well is 301 feet or more use 1 gal. of household bleach plus above

NOTE: The above table is for wells with a CASING SIX INCHES IN DIAMETER. If the well casing is not six inches in diameter, then figure the following:

1. Multiply the well casing diameter (in inches) by itself. (Square the diameter)
2. Multiply the results by the depth of the well. (in feet)
3. Multiply the results by .0302 to figure the required amount (quarts) of bleach.

Example: A 7” well casing on a 350 foot well = 7x7 = 49 x 350 = 17.150 x .0302 = 5 quarts

This will give you the Number of Quarts of Bleach required for disinfecting. Round off the number to the nearest HIGHER whole number to be safe. It is better to over-chlorinate than to under-chlorinate.

• Run all the faucets in the house, one at a time, until you smell the chlorine at the faucet. This ensures that the whole system is getting disinfected.
• Connect a garden hose to an outside faucet or an indoor tap with the correct threaded fitting. Put the other end of the hose into the well, turn on the faucet, and from time to time move the hose around so that the chlorinated water bathes the sidewalls of the well casing. Do this for at least six hours. Also disinfect the well casing cover. Then turn off the tap and remove the hose from the well.
• Replace the well cover.
• DON'T USE THE WATER for at least twelve hours. Forty-eight hours is optimal. Consider taking a weekend vacation, or using bottled water!
• Run the water to waste but NOT INTO THE SEPTIC SYSTEM for several hours, or until the chlorine odor is dilute enough to be unobjectionable. The best way to run the water to waste is to use a garden hose as mentioned above. Direct the hose into an area were the chlorinated water would not cause environmental damage or affect the water supply of others. For a typical well, this will take three or four hours.

NOTE: Constantly monitor the water flow to avoid pump overheating and possible damages, turn off the water if flow slows down to a trickle and wait at least 15-20 minutes before resuming the flush.

• Test for the presence of residual chlorine using DPP 1 and DPP 3 tablets.
• After testing the chlorine levels and the system has been flushed properly, retest for bacteria.
• In some cases, one chlorination treatment Will Not be sufficient. Repeat the disinfection procedures as needed.

Anatomy Of A Well***

Anatomy of a WellOn the outside, there are many different components of a well; each varies greatly between the well types (drilled, hand dug, cistern, etc), many state requirements, and their region. The most common well type in Maryland is a Drilled Well. Today, there are also many different state, county and even local requirements that must be adhered to. They protect the safety and health of humans and the environment. Basically, a drilled well has three major parts, the casing, the pump, and the cap, and several other components, screens, adapters, electric, benonite grout, and gravel, etc.

The casing is the tubular structure that is placed in the newly drilled well to maintain the opening. Newer wells today are made of PVC, which is light weight, easy to construct, inexpensive, and resists corrosion; but is venerable to heat. An older well is probably constructed of a metal, steel or cast iron, which is costly, susceptible to corrosion and deterioration, and can have a scale buildup. Some contractors may also use concrete, cement, asbestos, or fiberglass casings. In Maryland, a new well casing must rise 8” above the ground level, and 24” above the ground in a flood zone, to keep storm water run-off from contaminating the well.

The pump, usually a submersible pump, is the device that does exactly that, it pumps the water upwards from the source to the demand, the house. Pumps come in a large variety of sizes, horsepower, and quality. The factors that determine which pump to use depends on the depth of the well, the distance from the well to the demand (the house), and the expected demand of the house depending on the size and projected occupants. Another factor is the water table, supply, and the bedrock and/or aquifer levels. This is regulated and inspected at the state and county level.

The cap is the covering on the top of the casing. It may be a very small part overall, but is an extremely important one. A properly installed well cap separates potential pollutants from contaminating your drinking water. The cap should be sealed tightly at all times to prevent children from playing and everything from water run-off, bugs, vermin, rodents, and reptiles from wreaking havoc, and contamination. A “two piece vermin proof cap” is recommended today, which has several bolts (4-6) to protect the well.

How Well Water Reaches the House

How Well Water Reaches the House



From the well leading into the home there are generally two lines, the electrical supply which operates the pump, and the water supply line that runs from the pitless adapter which provides a sanitary seal and an avenue to bring the water into the home.






How Well Water Reaches the Consumer

Inside the home, and usually the closes wall adjacent the well location, is the electrical control box, pressure switch, pressure gauge, the pressure tank, and before and after shut off valves. At this juncture there may be a number of several water treatment devices installed based on the water quality, such as: softeners, conditioners, Reverse Osmoses (RO), carbon filters, UV lights, etc. From that point the water runs towards the water heater and/or towards the distribution of the house for consumption.

The electrical box should have its own designated shut off breaker inside (usually a 240 volt),and provide the proper amperage designed for the pump. The electrical box must be located with in specified distance of the pressure switch.

The pressure switch is the small (grey) box like device that controls the electricity to the pump. The size varies depending on the amps and horsepower of the pump. The switch cycles by demand usage, and turns on and off at a minimum and maximum PSI setting. Think of it as a brain for the pump and communicating the necessary water demand need from the pump.

The pressure gauge is located next to the pressure switch, and provides the PSI flow at all times. Often the gauge is damaged or faulty and thus sometimes unreliable. The gauge itself is a harmless component, replacing a damaged unit is recommended, because it allows a technician to properly adjust the pressure switch, if needed.

The pressure tank is the big tank (usually blue or grey) and comes in many sizes from 19 gallons to 124 gallons for residential usage. The newer homes of today have a 42-85 gallon size installed. The tank is usually made of steel, and is air tight and factory pressurized to 30 PSI. Inside the tank is a plastic or PVC type bladder, which is squashed flat by the pressurized air. As the water enters the tank, it too is pressurized by the pressure switch settings, as stated above, and thus when the distribution requires water, say at a sink, the air inside the tank pushes the water in the bladder outward for consumption. The tank also has a Schrader valve (similar to a bicycle tire) which allows adjustment to be made to the upper portion of the tank, where the air is concealed.

Pressure Tanks
Pressure TankPressure Tank

U.S. Government Links


The US Government EPA @ www.epa.gov/waterscience web site for the updated and current Drinking water Standards and Health Advisories tables.

Maryland Department of Environmental Health MDE @ www.mde.state.md.us/Water/index.asp

***The descriptions above are brief summaries of how a Well and their components work and should only be used as a quick reference. Well vary from types, manufactures, installers, and states.


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Providing residential, commercial and rental property inspections in Baltimore County,
Cecil County, Harford County and surrounding counties in Maryland!

Advanced Property & Environmental Contracting Services

P.O. Box 43957
Nottingham, MD  21236
License # 29775

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