Partner Blog

Information of use to those who serve private well owners.

FAQ: "Water from a Public Water Supply versus a Private Well?"


What are the differences between getting water from a public water supply (PWS) versus from a private well?


The public water supply is regulated so that the water being served to their customers is safe to drink.  A private well is not regulated and as the well owner, it is their responsibility to make sure the water is safe to drink.

Water from a public water supply must be tested to ensure it meets the USEPA Safe Water Act Regulations. The water is sampled at regular intervals for priority contaminants as identified by the USEPA.  These harmful constituents all have maximum contaminant levels (MCL’s) that are allowed by law, so the public water supply can only serve water that is below the MCL’s for all of the priority contaminants.  The primary drinking water standards can be found here: A private well generally has no legal requirements for water quality, and in general most health professionals recommend that the water quality of a private well meet the MCL’s, but that is simply a suggestion.  There may be some sampling requirements when a property is sold that has a well, and when a new well is drilled, but there is no continuing requirement to maintain a specific water quality of a private well like there is for a PWS.

A public water supply is required to have a responsible operator in charge (ROIC) who has a legal responsibility to make sure the water is safe. They have a water operator’s license, which they obtained by passing an operators exam, and they have to maintain that license by taking continuing education classes as required by their state/ jurisdiction.  A private well owner is solely responsible for the maintenance and safety of their water supply.

The homeowner pays a fee for their water when they are hooked up to a PWS.  That fee, spread across all of the customers of the PWS, pays for the operator and their staff, sampling costs, maintenance costs to provide water to the home, and for any treatment needed to remove harmful contaminants to below the levels identified by the MCL’s.  For a homeowner with a private well, you are solely responsible for all costs related to testing, maintaining, and running your water system.

If you have a choice, we recommend hooking up to a PWS.  Having a professional overseeing the water you drink is generally safer, and you are sharing the costs with everyone else on the same PWS.  HUD and FHA loans require that you look to a PWS for water, if it is feasible, for just that reason.  It ensures a safe water supply that is regulated.  Many private well owners are so because they have no choice, there is no PWS nearby to hook onto.  That’s ok, there are 14 million private wells in use in the US, and the vast majority provide a safe, steady supply of water.  It just means that a private well owner has to be a responsible steward of their well and water supply.  They have to understand how their well works, how to maintain their well, and what steps are necessary to ensure a safe water supply. 

FAQ: "What Should I Sample For?"


How often should I sample my well, and what should I sample for?


Testing your water regularly is probably the most important thing you can do to protect you and your family’s health.  In most cases, groundwater is completely safe to drink, but sometimes there are naturally occurring contaminants in groundwater, and many older wells do not properly protect from possible surface contamination and can lead to well contamination.  

What to sample for can vary based on well depth, known naturally occurring contaminants, and local concerns.  Including the list of things we recommend, you should contact your local health agency and ask them what they suggest. It might also be helpful to contact your local cooperative extension office or driller to ask if they know of any concerns in your area. In some states, one or more state agencies might have information on water quality that will be helpful.  Below are two examples. In Massachusetts, you can type in your address, and the system will let you know if you are at risk for Arsenic or Uranium (Figure 1), and in Rhode Island, the middle of the state has a beryllium issue (Figure 2). Investigate, so you aren’t surprised later.  We have had more than one well owner contact us, upset that they didn’t know there was an issue in their area, like arsenic, until after they purchased their home.


Fig 1. From the Massachusetts DEP website

From the Rhode Island Dept of Health (large pink splotch in the middle of the state)

We recommend sampling for nitrate and coliform bacteria annually. These constituents are common and provide an indicator that there is likely a pathway into your well from or near the surface. In some cases they can indicate contamination from your septic system or from livestock, which should not happen if your well is properly located and constructed.  The point of sampling annually for these two relatively inexpensive constituents is they will point out an immediate problem that should be dealt with. If you do have coliform bacteria in your well, you should not drink it until disinfected, and you should also test for E. coli as a follow up. Contact your local or state health agency, and they can give you follow up recommendations.

We also suggest sampling for the following constituents once every 3 -5 years.  Again, we recommend you contact your local health agency for advice and additional information.  The goals we all share are safeguarding public health and source water protection. Sampling for the constituents below will give a water quality professional a lot of valuable information about your well water, including its corrosiveness and other information needed to make treatment decisions.
Arsenic Fluoride
Iron Sulfate
Lead Hardness
Manganese pH
Chloride Turbidity
Total Dissolved Solids Copper (if copper piping)
Zinc and Cadmium (if galvanized piping in home or well)

FAQ: "What is a Well Log?"


Where can I obtain my well log and what information does it contain?


Depending on your location, your state or county health department, Department of Natural Resources, or some other similar agency may house well logs that you can access or request a log from. If you know who drilled your well, it might be a good first step to contact them and ask for your log. They should be able to provide a copy to you. If not, search online for ‘“your state” well construction code’ and the relevant state agency should come up. Call them, and find out what agency houses well logs, if any, and that will get you on your way.

You will need to know the legal description of the well location, and additional information that will be helpful include the drilling company that installed the well, the depth, the date drilled, and the original owner, if not you. In some states, only the owner can request the log, but in others it is public information. ;There are a number of states, including Illinois, that have websites with interactive maps that allow you to zoom into your location and see what logs are available, as well as other information in some cases, like water quality information.

The problem many well owners find is that there log is not on file with these agencies. The laws have changed over time, but 40+ years ago, most states did not require a driller to get a permit or file a log, so if you have an older well, the drilling company might be your only hope. In these cases, if there is information that you really need, like pump or well depth, it might be that you need a contractor to come out and determine this for you.

As far as what is on a well log, this also varies by state and jurisdiction. Below is a well log from Illinois, and this is what we can say about this well based solely on the log. This is a 318 ft deep well, constructed with 314 ft of PVC and a 4’ stainless steel screen at the bottom. The water bearing unit is course gray sand from 307-318 feet below land surface. Sim’s Drilling Company drilled the well for Tom Parrett, the land owner. It shows the legal description of the location as well as the location in decimal degrees. The static water level is 140 ft below land surface, meaning there is about 180 feet of water in the well. They installed a 18 gpm submersible pump at 200 ft, meaning there is about 60 feet of water over the pump. It’s for domestic (home) use, the well was completed on 8-3-06, and the pump was installed on 9-6-06. They grouted the annulus from 5 feet below land surface to 148 feet below land surface as well.

If you are able to retrieve your well log, hopefully it has at least this information. It really does differ by jurisdiction.

FAQ: "Do Septic Additives Work?"


Should I use any additives in my septic system?


The short answer is no. A septic system works best on its own as long as it is maintained and the wastewater going through it is from normal household use. There is a huge market for additives claiming to make it function better or prolonging the life of the system, but research and experts agree, that its best to leave it alone, the bacteria we add naturally work best and don't need any help.

We interviewed a number of well and septic experts, and looked for actual research to support or refute claims of the benefits of additives. We found nothing definitive about the benefits of additives, but a number of things about the potential harm additives can cause, especially some chemical additives.

Two good resources on the subject are from the Purdue Cooperative Extension and the National Environmental Services Center (NESC), both of which are discussed below.  We also talked with 2 private well experts who manage state programs that work directly with well owners. Both said they, and other experts they have discussed this with, agree that there is no evidence to support that additives provide any benefit. They added that there is evidence that some chemical additives can damage the natural bacteria populations in a septic tank or allow solids to get into a septic field. Lastly, we contacted the USEPA, and their response followed suit, “Proper care and maintenance every 3-5 years (pumping the tank to remove solids) is recommended. All additives do is give the homeowner a false sense of security that their system will be fine if they add it.”

When we first answered this question as part of a septic webinar we conducted in the summer of 2015, we received a bunch of emails from homeowners who swear by their additives and some claimed to only pump their tank every 10 or 20 years. One stated that they had never had to pump their septic tank. We were given websites that provided “evidence” of a particular products success, even videos showing how they work. The problem with all of these testimonials are that the conditions of the testing are not the natural conditions in a tank. There was evidence to support these products under actual conditions in a septic system. These folks are likely in for a surprise at some point when their septic system fails and they either have septic effluent pooling in their backyard, or worse, backing up into their home. Also consider that in some cases the money spent on additives over a 3-5 year period would have likely paid for pumping and inspecting their tank.

Additional Resources

Purdue Extension - This handout does a great job of giving an overview of what the functions of a septic system are and how additives might affect it. It describes the types of additives that are out there, and how their use might impact a septic tank. They recommend good “habits” for how to improve performance of a septic system, by reducing the chemicals used every day that might harm the bacteria in a septic system, and best practices for reducing the amount of flow going through a system.  Improving daily habits can go a long way at preserving the proper function of a septic system.

NESC’s Small Flows Clearinghouse and Magazine - The National Environmental Services Center at West Virginia University has a national technical assistance hotline. The article at the link above was developed from calls they received from homeowners asking about additives for their septic systems. They describe some of the findings from several research studies on additives, but the question we are interested in, “Do I need to use additives…” is the last section on the 2nd page. My favorite statement, “Contrary to popular belief, yeast, dead chickens, possums, or raw hamburger do not need to be added to the septic tank”, pretty much sums up the folklore and home remedies that have made their way into this conversation.

Note: Hideyuki Terashima at the Illinois State Water Survey did all of the legwork to find and put together the resources used here on this topic. We originally used this information as part of a webinar on septic system issues in May 2015. As part of that webinar, we had a licensed septic installer and inspector participate in answering well owner questions.

FAQ: "Shock Chlorination Didn't Work"


I have shock chlorinated my well several times, but my sample results still come back positive for bacteria. What can I do?


Reoccurring bacteria problems mean there is a source of bacteria somehow connected to your well at the surface. It could be that your well is in a vulnerable geologic setting, meaning the groundwater itself is being contaminated from the surface and getting into your well. The other likelihood is that your well has a breach or was poorly constructed and allows near surface water into your well.  If your well is shallow, then the water coming into your well is from near the surface and more likely to be contaminated if there is a source nearby (usually livestock or septic). If so, this will always be an issue for your well. As an example, in New York there are many areas where a commonly used bedrock aquifer is at or near the surface, and because of this many shallow wells in this aquifer setting are vulnerable to surface contamination. Another vulnerable geologic setting is in karst areas, where you find caves, caverns, and sinkholes, all of which are conduits for surface contamination.

If you have a dug or bored well, they are made to allow water to seep into the well bore from the surrounding area over most of the depth of the well. They are typically more susceptible to surface contamination because of where water is getting into the well. If you have a deeper well, with casing to a considerable depth, it could also be that the well wasn’t properly constructed, maybe it wasn’t grouted properly so water can run down along the outside of the casing, or there are holes in the casing allowing water into the well from near the surface.

There are really only two solutions to this issue, properly construct a well into an aquifer that is not influenced by the surface (so in the NY example, it would have to be a different, deeper aquifer if one exists), or add continuous treatment to treat for the bacteria. The most common treatment is either a continuous chlorination or ultraviolet disinfection. If you are considering either of these alternatives, contact your health department for advice. Both have maintenance needs and you should understand the responsibilities of adding treatment.