Treating well water? It's kind of amazing to think about it. According to the National Groundwater Association, 47 percent of the U.S. population depends on groundwater for its drinking water supply. Of that 47 percent, many get their water from a private well. 

If you have a private well, are new to well water, or are interested in learning about treating well water, you might also want to know how groundwater and water wells work.

What is Groundwater?

Groundwater is water that soaks into the soil from rain or other precipitation and moves downward to fill cracks and other openings in beds of rocks and sand. It’s a renewable resource, although renewal rates vary greatly according to environmental conditions. Here in California, we recently experienced a serious drought, but thankfully, this past winter, we had ample rains.

It is also an abundant natural resource. Of all the fresh water in the world (excluding polar ice caps), 95 percent is groundwater. Surface water (lakes and rivers) only makes up three percent of our fresh water.

Scientists estimate U.S. groundwater reserves to be at least 33,000 trillion gallons, equal to the amount discharged into the Gulf of Mexico by the Mississippi River in the past 200 years.

Groundwater is naturally filtered by the earth that holds it. It can, however, be contaminated by pollutants that come into contact with the earth’s surface. Care should be taken at the household, local, national, and global levels to protect groundwater from pollution.

The Making of Groundwater

Water from rain and snow follows three main paths:

1. Some water evaporates from the earth’s surface into the air or is breathed out by vegetation and returns to the earth’s atmosphere. Some water runs off into streams, lakes, or oceans.
2. Some filter into the ground. There, it can flow to the surface as springs, move into surface water, or recharge groundwater deeper in the earth.
3. Groundwater can move into large underground natural storage areas known as aquifers and/or artesian wells.

As groundwater moves through the ground, it dissolves some of the minerals it comes in contact with, such as limestone, iron, and others. Those dissolved minerals give groundwater its chemical character or quality.  

Much bottled water comes from groundwater reserves.

Groundwater and Private Water Wells

Frequently, private water wells tapping groundwater resources can provide the highest quality water available to homeowners and businesses. Deep-drilled wells recharge themselves and can provide a constant, steady supply of water that is not easily impacted by dry weather conditions.

According to an independent market survey sponsored by the National Ground Water Association (NGWA), 78 percent of private water well owners prefer receiving their drinking water from their wells. Eighty-eight percent of those surveyed said private wells were their least expensive drinking water option.

Private water wells also allow homeowners to exercise greater control over their water quality. They can store the water and have it available for emergencies.

What exactly is a drilled well?

A drilled well consists of a hole bored into the ground, with the upper part being lined with casing. The casing prevents the collapse of the borehole walls and (with a drive shoe or grout seal) prevents surface or subsurface contaminants from entering the water supply.

The casing also provides housing for the submersible well pump and the pipe that moves water from the pump to the surface.

The lower portion of the borehole below the casing is the intake through which water enters the well. Depending on the geologic conditions, the intake may be an open hole in solid bedrock or screened and gravel-packed.

Once the well is completed, it is pumped to develop the well and determine the yield.

Many areas need further work after drilling to remove fine material remaining from the drilling process so that water can more readily enter the well.

The quantity of water (yield test) is usually measured during development. The minimum test time is one hour.</span

An important step is disinfecting the water to kill any bacteria present or that may have been introduced when the well was drilled or worked on.

After proper disinfection, the well is capped to provide sanitary protection until it is hooked into the customer’s system. Well, caps require an air vent.

Most wells use submersible pumps, which are down in the water and pump out to the home. Your pressure switch turns the well pump on and off automatically, maintaining a good range of pressure in your home.

If you see your well pump on top of the ground, then that is what is called a jet pump. It is sucking water up out of a relatively shallow well (usually 30 ft or less in depth). These types of shallow wells are much more prone to contamination.

Most states and provinces do not regulate or have jurisdiction over private wells serving a single home or farm. Thus, the responsibility for protecting private wells is squarely on the well owner.

Potential Sources of Private Well Contamination

Before you can go about treating well water, you might want to have your water tested and also look for signs of contamination by testing the water.

If you live in a rural area with your own well, the well often has a number of potential sources of groundwater contamination near the wellhead:

• Septic system
• Improper waste disposal – paints, lubricants, dead animals, cleaning products, etc.
• Pesticide and fertilizer storage, mixing, and loading
• Livestock pens, corrals, manure stockpiles, and lagoons
• Leaky silos or underground silage pits
• Lawn and garden chemicals
• Abandoned or poorly sealed wells
• Old waste dumps
• Underground storage tanks  
• Equipment and vehicle cleanup and maintenance
• Fuel storage, old underground fuel tank                                                                                                     
• Hydro-fracking involves injecting steam and chemicals into the ground to extract petroleum from oil shale formations. Fracking operations can contaminate some local wells, although typically, they occur at far deeper depths than the groundwater layer and have little overall effect (as far as we know at this time).

Older wells in shallow aquifers are more likely to be contaminated. The soil and geologic material that overlies the aquifer greatly influences the relationship between surface activities and groundwater quality.

Deeper wells often pass through more restrictive or impermeable layers that decrease the rate at which surface water reaches the aquifer.

You should talk to the driller who installed their well about the hydrogeology of their site and ask for a copy of the well log (a record of well construction and geologic formations encountered).

While all wells need protection, it is especially important to observe good management in the vicinity of a shallow or vulnerable well.

What Can You Do To Prevent or Correct Contamination?

State regulations encourage good well location by requiring a minimum separation distance of 100 horizontal feet between newly constructed wells and any source of contamination

The required setback for septic tanks and sewer lines is 50 feet. Some counties have greater setback requirements.

Contamination related to an inadequate well cap or missing grout seal would most likely result in the presence of coliform bacteria in your well water.

Thus, the first step in the proper management of an existing private well is an annual test for total
coliform bacteria.

This test can be arranged through a local certified laboratory and there are also home test kits available.

If your well tests positive for coliform bacteria, a sanitary well cap may help solve the problem, especially if your well contains small numbers of bacteria.

You may also want to have your well sanitized with chlorine or do it yourself.

Be sure to disinfect your well with a 100 ppm bleach solution (1 cup household bleach in 31.2 gallons of water) any time the system is opened for maintenance or repair. Depending on the depth, different levels of chlorine and chlorine pellets or powder can be used. A high-level chlorine test kit is recommended when shocking a well with chlorine to avoid adding too much (hard on pumps and other well parts) or too little.

Also read:

7 Signs Your Water Well is in Trouble

Additional Resources on Well Water Treatment:

1. California State Water Resources Control Board – Residential Water Treatment Devices: This page discusses various water treatment devices and their effectiveness in treating different contaminants in well water. California State Water Resources Control Board
2. Rhode Island Department of Health – Filtration and Treatment of Private Well Water: Here, you can find information on how to choose a water treatment system for your private well, including contact information for further assistance. RI Department of Health – Well Water Treatment
3. State Hygienic Laboratory – Well Water Quality and Home Treatment Systems: This PDF document offers insights into home treatment systems for well water, including traditional methods and modern technologies. Well Water Quality and Home Treatment Systems

Frequently Asked Questions (FAQs)

1. What is groundwater, and how does it form?
Groundwater forms when rain and snow seep into the soil, moving down to fill cracks in rock and sand layers. It's a major source of fresh water in the U.S.

2. How does a private water well work?
Private wells tap into groundwater sources. Most use a submersible pump and casing to draw and protect the water, providing a constant supply to the home.

3. What can contaminate a private well?
Contamination can come from nearby septic systems, agricultural runoff, fuel storage, or improper waste disposal near the wellhead.

4. What is the difference between a jet pump and a submersible pump?
Jet pumps sit above ground and are used for shallow wells. Submersible pumps are installed in deeper wells and push water to the surface.

5. How can I protect my well water quality?
Test your water annually for bacteria, install a sanitary well cap, maintain proper setbacks from contaminants, and disinfect your well after any system work.