Understanding Your Water Test Results
After laboratory analysis is complete, you will receive a report showing the parameters tested and the concentrations detected in your sample. For many property owners, a professional laboratory report can initially seem difficult to interpret because it may contain abbreviations, scientific units, reporting limits, and regulatory references.
When reviewing your results, focus on several key pieces of information:
- Parameter: The specific substance or water-quality characteristic measured, such as lead, nitrate, arsenic, hardness, or pH.
- Your Result: The concentration or measurement detected in your specific water sample.
- Units: Results may be reported in units such as mg/L, µg/L, or another method-specific measurement.
- Applicable Standard or Guideline: Depending on the contaminant and type of water, the report may reference an EPA Maximum Contaminant Level, Secondary Maximum Contaminant Level, health-based guideline, or another benchmark.
A Maximum Contaminant Level (MCL) is an enforceable limit established by the U.S. Environmental Protection Agency for certain contaminants in public drinking-water systems. By contrast, Secondary Maximum Contaminant Levels (SMCLs) generally address non-health-related characteristics such as taste, odor, color, staining, or other aesthetic effects.
The EPA provides additional information through its National Primary Drinking Water Regulations and Secondary Drinking Water Standards.
If a result is below an applicable MCL, it means that particular contaminant was measured below the referenced federal limit. However, this does not automatically prove that the entire water supply is free from every possible contaminant, especially if only a limited testing panel was performed.
If a result exceeds an applicable standard or guideline, the next step should depend on:
- The specific contaminant
- Its concentration
- The water source
- Applicable local requirements
- Whether confirmation testing is needed
- The likely contamination source
Corrective action may involve additional testing, plumbing investigation, treatment, well maintenance, or consultation with a qualified water professional. Treatment should always be selected for the contaminant actually detected rather than assuming one filtration system will solve every water-quality problem.
Water conditions can also vary considerably by region because of:
- Local geology
- Groundwater characteristics
- Agricultural activity
- Industrial history
- Municipal infrastructure
- Plumbing materials
Property owners looking for testing support relevant to their area can review available water testing service locations and discuss local risk factors when selecting an appropriate testing panel.
Establishing Better Control Over Your Water Source
Working with a professional laboratory helps replace assumptions about water quality with measurable data.
Appropriate water testing services can help identify specific chemical, physical, or microbiological conditions that may require further attention.
Laboratory results can support decisions involving:
- Drinking-water quality
- Plumbing and corrosion
- Treatment-system selection
- Private-well management
- Follow-up monitoring
- Investigation of unusual water conditions
The goal of laboratory testing is not to declare that every sample is completely pure. Instead, it provides reliable scientific information about the parameters actually analyzed.
That information allows homeowners and property managers to make informed decisions based on measured results rather than appearance, taste, odor, or guesswork.
For help interpreting results or deciding which additional analyses may be appropriate, you can contact a professional water testing laboratory to discuss your report, water source, property conditions, and specific concerns.