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how do i test my well water?

How Do I Test My Well Water in a Lab?


As a well owner, you probably already know that you need to test your well water regularly. Because your drinking water is your responsibility, getting your well water tested in a certified lab is the best way to get a clear picture of your water quality. It's also much easier than you think! 

In this guide to laboratory testing for well owners, we’ll give you the ins and outs of well testing including sampling procedures, what to test for, and how often to test.

Table of Contents:

What Should You Test for in Your Well Water?

While there are many parameters (a.k.a. “analytes” or “contaminants”) worth testing, the two most important well water contaminants to test for are:

  • Coliform bacteria (like E. coli)
  • Nitrates

Why Is Testing for Coliform Bacteria Important?

A positive coliform test indicates that there is a pathway for potentially dangerous bacteria to enter your well. While not all coliform bacteria are harmful to human health, pathogenic and harmless coliform bacteria can come from the same sources, so the presence of any coliform bacteria in well water means there is a risk for illness.

How Does Coliform Bacteria Get into My Well?

Coliform bacteria is naturally found in human and animal waste and it may enter your well due to broken septic systems, agricultural runoff, or poorly constructed/damaged wells allowing surface contaminants to enter the groundwater directly.

why should i test my well for coliform bacteria?

A Quick Guide to Coliform Bacteria in Well Water

Why Is Testing for Nitrates Important?

Testing for nitrates is important because the vast majority of wells are in rural areas, drawing water from an aquifer. Nitrates, which are found in animal manure and agricultural fertilizers, pass through soil and into groundwater supplies.

It is especially important to know if nitrates are in your water if there is an infant or a pregnant person in the home. Nitrate exposure in infants can cause blue baby syndrome (which prevents a baby’s blood from carrying oxygen throughout their body).

What Is the Safe Level of Nitrate in My Well?

Set by the EPA, the Maximum Contaminant Level (MCL) for nitrates in drinking water is 10 PPM. This is also the health-based guideline for nitrate in drinking water.

What Other Contaminants Should I Test for in My Well Water?

The list below is provisional and based primarily on the most common problems for wells nationwide. However, groundwater is very context specific! It's important to take this list as a starting point, and do the required research on your local area to know what's most important to test.

    • Initially
      • Arsenic
      • Lead
      • Manganese
      • Fluoride
      • Hardness
      • Any relevant radionuclides
      • Annual list (below)

    • Annually
      • Total coliform
      • Nitrate
      • pH
      • TDS
      • Any contaminants of local concern
      • Every 3-5 years
        • Arsenic
        • Lead
        • Manganese
        • Fluoride
        • Hardness
        • Any relevant radionuclides

      Additional Parameters

      As we mentioned above, you’ll want to pay close attention to the local context of your well. Be sure to contact your local health or environmental health department to discuss any contaminants of particular concern in your area.

      Because wells draw from groundwater sources, heavy industry, industrial dumps, factory farming, and even military bases and airports in your geographical area can have big impacts on water quality—like hazardous chemicals leaching into your water supply.

      If you live in an area where large, industrial agricultural activity takes place  (i.e., “factory farms”) some additional contaminants of concern include:

        • Volatile organic compounds (VOCs)
        • Petroleum products
        • Pesticides (herbicides, insecticides, and fungicides)
        • Emerging contaminants (such as PFAS and PPCPs)

      Many of these contaminants cannot be seen, smelled, or tasted so testing your water is the only way to find out if they’re in your water. This core kit takes all of the crucial contaminants into account and adds some of the additional parameters mentioned above, like VOCs and petroleum products.

      How Does Agriculture Pollute Private Wells? 
      Ultimate Guide to Well Water Contaminants

      Testing Your Well Water

      What's in a Well Water Sampling Kit?

      These are the typical components of a well water sampling kit. Some tests may also include specialized components such as ice packs to keep your sample cool.

        • Instructions
          You'll receive detailed instructions with your well water sampling kit. The instructions will tell you how to collect your sample. Read your instructions carefully before and during testing.
        • Sampling Containers
          Your sampling kit will include one or several sampling containers (glass or plastic). Some may include preservatives to keep the sample stable.
        • Sample Information Card
          A Sample Information Card and/or Chain of Custody Form should accompany every sample. You will use this form to record details about the sampling method, date, time and location of your sample.
        • Free or Paid Return Shipping Labels
          If you ordered your water test kit online, be sure to save the box and check if a shipping label is already included. This can save you money. 

        How to Collect Your Well Water Sample

        The water sampling itself is usually straight-forward, but remember to follow your test’s instructions carefully. The decisions you make during sampling can affect your results.

          • Choose WHERE to sample
            Most water testing kits will be for a single location. While there may be many bottles or vials, never put water from different sources in them, because the different bottles test for different contaminants or serve as important back up samples.

            The location you chose to collect your sample will influence what your results mean. For example, sampling directly from the well head will tell you about your well, whereas sampling from your kitchen faucet will tell you about the well PLUS your plumbing and any other fixtures.

            If you have a water filter you need to decide whether to test the filtered or unfiltered water. You can opt to buy two test kits and run a filter performance test, analyzing the water filter before and after installation.

          • Choose WHEN to sample
            The time of day you collect your water sample can also impact your results.

            Certain plumbing-dependent metals like lead are most likely to show up after water has sat in the pipes overnight. For sampling bottles labeled for metals testing, you may choose to collect them first thing in the morning. This is generally called a “First Draw Sample.”

            Dissolved gasses and other VOCs are more likely to diffuse out of the water if they sit in the plumbing for a long time. To capture whether your water has VOCs (or radon) it’s often better to let the water run for a few minutes first.

        Sample your water

        Best Practices When Collecting Your Water Sample

        1. Do not rinse out the inside of the containers.
        2. Do not touch the inside of test vials or their lids.
        3. If possible, remove any aerators or other faucet attachments from the sample location.
        4. Collect all your samples from the same source (e.g. faucet or well-head).
        5. Use a low flow when drawing water.
        6. Close lids tightly! You don't want them to spill in transit.

        You might receive separate packages from the lab. If you do, then take care to not mix up the contents of the packages.

        Well Water Sampling Containers

        Returning Your Samples to the Lab

        Remember to either drop off or ship your samples as soon as possible after collecting your samples and avoid shipping on weekends. If you need to wait before dropping off or shipping, try to keep your samples refrigerated if indicated.

        If you’re driving to the nearest certified environmental testing lab, it helps to know their receiving and closing hours. If you're testing with Tap Score, you'll find a pre-paid return label included.

        Being prepared helps you avoid any unforeseen issues.

        Don't forget to include your sample information card or chain of custody form with your sample!

        Tap Score well water testing kit

        Tap Score Well Testing Kits

        Testing with Tap Score is easy! All of our water testing kits include everything we’ve mentioned above—including free shipping back to the lab.

        Which Test Kit Is Right for Me?

        The Essential test kit is a great place to start if you’ve never tested your water before. However, the Advanced test is recommended thanks to its more specialized contaminants like VOCs and petroleum compounds. 

        The Extended well test is a great choice for new wells and/or new well owners. The widest scope available, the Extended Well test gives you the most comprehensive picture of your well water quality available. It’s a good idea for all well owners to consider this test once every 5-10 years. 

        How Can I Find a Drinking Water Testing Laboratory?

        Finding a water testing lab isn’t always easy, and as a well owner, testing your water is your responsibility. Most state’s have health boards or environmental protection agencies that share lists of certified labs.

        Tap Score has prepared a state-by-state guide to certified water testing laboratories. If you choose to test with us, however, we simplify the selection process and handle all of the back end so you only have to think about collecting your sample.

        Interpreting the Results of Your Well Water Test

        Once the lab receives your water sample they'll analyze it according to the necessary testing methods. Turnaround times vary depending on the contaminants chosen for analysis. 

        Your results will show the concentrations of contaminants in your sample.

        What Are the Units on My Well Water Results?

          • Parts per million/ppm = mg/L of water (equal to putting ONE drop of water from an eyedropper into 10 gallons of water)
          • Parts per billion/ppb = µg/L of water (equal to ONE drop of water in a 10,000-gallon swimming pool)

        Is My Well Water Safe to Drink?

        A well that is properly looked after in an area without compromised groundwater should produce perfectly safe drinking water. Well water with any bacterial activity or nitrates and/or heavy metal concentrations above the EPA’s MCLs should be treated right away.

        As a guide, the EPA sets legal limits for nearly 100 contaminants called Maximum Contaminant Levels (MCLs). They also provide Maximum Contaminant Level Goals (MCLGs)—thresholds based on health-based toxicology research. While these regulations have no impact on well water (because they are only enforceable at the public water system level), they are good indicators of health risks in your results.

        Compare these limits to your own water report to get an idea of how well your water quality stacks up. Most labs will indicate if your sample exceeds an MCL, but you’ll want to evaluate your results against MCLGs to know if there is a health concern.

        Note: While some contaminants have an MCLG of zero, it is often not possible to completely eliminate them from your well water. This just means that health recommendations state the concentration of the contaminant should be as low as possible compared with the MCL.

        Are There Other Concerns Around Well Water?

        There are health standards beyond the EPA’s federal guidelines. Talk to your lab or Tap Score’s Support Team of water quality experts if you want more information about other kinds of health and aesthetic thresholds in your drinking water. A common and highly regarded source is California’s Office of Environmental Health Hazard Assessment’s Public Health Goals.

        Talk to an expert

        You or a family member might have health conditions or concerns that require you to treat water quality for contaminants NOT covered by the EPA. Consult your doctor and health experts to know what levels are safe for your family. 

        Also consider any pets you might have. Particularly small animals and aquarium fish are vulnerable to contaminants.

        Additionally, Private Well Class runs a Pledge to Test Campaign during Groundwater Awareness Week (March 10-16) each year. Private Well Class is a program aimed at boosting the knowledge and competency of individual well owners.

        How Much Does it Cost to Test Well Water?

        The cost of lab testing depends on the contaminants you test for. You'll find tests for as little as $60, but those might not give you a thorough analysis of how safe your water is to drink. Laboratories use state of the art equipment to perform their analyses, and different techniques are required for different analytes. Both of these things factor into the price of a high quality water test.

        A good overview of your well water quality will run around $200-$300, but it's possible to spend $2,000 for extremely thorough tests. Talk to an expert first to determine what’s necessary and choose the test that fits your budget.

        Can You Get Your Well Water Tested for Free?

        Your local or state health department may occasionally refer you to a certified environmental laboratory for a free test. However, most of these tests are very narrow in scope and might only include testing for analytes like coliform bacteria and/or lead.

        Some communities offer “Test Your Well” events where you can get a free well water screening.

        We do not recommend "free" tests conducted by filtration companies—they often double as pushy sales tactics.

        Do DIY Test Strips Work for Well Water?

        Only for quick readings of a few parameters (like free chlorine, pH, hardness). You can find cheap water test strips at just about any hardware store, but these at-home testing strips have major flaws you should be aware of before you buy.

          • DIY strips and kits can be inaccurate.
          • DIY tests cannot test for most contaminants.
          • Test strip results might be instant, but can be confusing to interpret.
          • Test strips won’t include the same professional support you’d get from a certified laboratory.
        Are DIY Water Test Strips Accurate?

        How Often Should I Test My Well Water?

        The EPA suggests you test your private well at least once a year. Test more frequently if your well is shallow or if you have a surface water source (lake, river, stream, or reservoir) as these types of sources are more vulnerable to contamination.

        Pay close attention to the local context of your well. Be sure to contact your local health or environmental health department to discuss any contaminants of particular concern in your area. 

        You should test…

        • Initially for arsenic, lead, manganese, fluoride, hardness, any relevant radionuclides + annual list
        • Annually for coliform bacteria, E. coli, nitrates, pH, TDS, and contaminants of local concern (e.g., certain pesticides, PFAS, etc.)
        • Every 3-5 years for arsenic, lead, manganese, fluoride, hardness, and any relevant radionuclides
        • Anytime your water has a change in taste, odor, or color  
        • Anytime there is a nearby natural disaster or chemical spill
        • Anytime you install a new well or open your well to service it
        • Anytime your well is tampered with or damaged
        • After installing a water treatment device
        • If a baby is expected in the home

        What’s the Takeaway?

        Always test your water before spending money on a water filtration or treatment system.

        • The two most important contaminants to test your well water for are coliform bacteria and nitrates. You should test your well at least once a year, and anytime there is a change in taste, color, or odor, or a natural or industrial disaster in the area.
        • Remember to follow your sampling instructions very carefully. The decisions you make during sampling can affect your result.
        • You can use the EPA’s Maximum Contaminant Levels (MCLs) and Maximum Contaminant Level Goals (MCLGs) to understand the health risks of your results.
        • Tap Score’s Advanced Well test is a great place to start if you’ve never tested your water before thanks to its blend of essentials like bacteria, heavy metals, and nitrates, and more esoteric contaminants like VOCs.
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        About The Author


        Serving as the CCO at SimpleLab, Jorgen has been an integral part of Tap Score since its inception. With a passion for combating misinformation in the water industry, he is dedicated to empowering individuals with a clear understanding of the fundamentals of their drinking water. In his spare time, Jorgen enjoys creating immersive social experiences for Virtual Reality with his wife.
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