Interpreting Water Quality Results


Water Quality Testing

In this study, multiple methods of measuring water quality are utilized to measure the amount of contaminants in the water sample.

  • Community scientists will use water testing strips capable of measuring 14 parameters on one strip (Baldwin Meadows 14-in-1 Drinking Water Test Kit).
  • The Ohio State University Lab will use various analytical techniques and instruments including membrane filtration, gas chromatography mass spectrometry, liquid chromatography mass spectrometry, ion chromatography mass spectrometry, ion coupled plasma mass spectrometry, and others.

Water Quality Resources and FAQs

How is water quality regulated? The United States Environmental Protection Agency (EPA) is responsible for regulating water quality. The EPA decides things such as which contaminants to regulate, what levels of exposure to these contaminants are acceptable to public health, and what corrective actions need to be taken to ensure those regulations are met to protect public health. You can read more on this topic here: How EPA Regulates Drinking Water Contaminants.

Are there any requirements for reporting water quality to the public? According to the United States Environmental Protection Agency (EPA), all utilities are required to provide consumers with information about their water quality. Here is a quick reference on the requirements of all Consumer Confidence Reports: Consumer Confidence Report Rule.

Where can I get my Consumer Confidence Report? You can access the Northwest Regional Water District’s historical Consumer Confidence Reports (CCR) here: Northwest Regional Water Consumer Confidence Reports.

How do I know if my water is safe? According to the EPA, water is considered safe if it meets the requirements outlined in the National Primary Drinking Water Regulations, which provides Maximum Contaminant Levels (MCL) for each regulated contaminant. You can find a table of MCLs for regulated contaminants here: National Primary Drinking Water Regulations.

How are MCLs established? The safety of water is determined by the EPA using scientific data. MCLs are established based on health impacts and risk of those impacts from certain levels of exposure to different contaminants. You can read more about how MCLs are determined here: Determination of MCLs.

What affects my level of exposure to contaminants? Exposure depends on factors like source water quality, the effectiveness of treatment, the likelihood of post-treatment contamination, the route of exposure (e.g. inhalation, ingestion, skin contact), the frequency of exposure, duration of exposure, and amount of contaminant that you are exposed to each time.

What happens if MCLs are exceeded? MCLs are enforceable regulations. Utilities will be cited with violations and required to make changes to ensure the water quality meets regulations.

How do the water test strips work? Test strips change color based on the level of substance (contaminant) in the water that reacts with compounds in the test strip. The color or intensity of color signals the level of the substance (e.g. darker color means greater concentration of the contaminant in the tested water sample).

Are water test strips accurate? Water test strips are designed as low-cost, simple to use, rapid diagnosis tools for substances in environmental samples. Not all water test strips are designed equal. Water test strips are affected by manufacturing, storage conditions, expiration date of the strips, and the technique of the user. Follow handling and usage instructions to get the best results. One study examined water test strips used to make farm management decisions: Assessing the Reliability of Water-Test Kits for Use in Pond Aquaculture: Assessing the Reliability of Water-Test Kits (Naigaga et al., 2017; DOI: 10.1111/jwas.12377).

Does the water sampling process or storage affect my water test results? Depending on how you collect your sample, you may introduce contaminants into your water. The holding time, whether in your house, in transit, or at the lab, of the sample and the holding conditions (temperature, preservatives, light exposure) may affect the level of contaminants in water. Samples are usually stored at 4°C to maintain sample integrity. Different kinds of water analyses may require water samples to be collected in special containers or with preservatives.

What happens if my water has levels of contaminants higher than the MCL? (work in progress)


Work in progress…more to come!