When to test your water


For non-water providers

Municipalities are required to test their water supplies based on the drinking water monitoring schedule to ensure the water is safe. However, there is no requirement to test a private well except when it’s first drilled or the pump is changed. Homeowners are responsible for making sure their water is safe.

As a private well owner or well-water consumer, you'll probably use groundwater from your well for drinking, cooking, bathing, doing your laundry, and watering your garden. While most private wells provide a clean, safe supply of water, contaminants can pollute private wells. Because you can't see, smell, or taste most contaminants, test your well water on a recommended annual basis. The types of land uses near your well will determine which tests need to be performed on your water supply.

Learn how wells are polluted, how to protect them, and what pollutants contaminate the water

If your home uses a city or municipal water supply, consider the following water tests:

  • Lead
  • Hardness

Water testing suggestions

  • If you own property with a private water supply such as a spring or a well, consult this list for testing suggestions:
  • Because bacterial levels in the water can change over time, a coliform test should be performed yearly.
  • If there’s farming or livestock ranching in the area, nitrates can be in areas where fertilizers were applied or there is livestock waste.
  • If children are drinking the water on a regular basis, fluoride levels should be between 1 and 2 milligrams per liter (mg/l). 
    • Fluoride levels of less than 1 mg/l may prevent the proper development of teeth, and you may need supplements. Fluoride levels greater than 4 mg/l can lead to a pitting and staining of the teeth caused by fluorosis.
  • If your water has an odor that smells of rotten eggs, this may indicate the presence of sulfide. This is more of an aesthetic problem than a health concern and can be easily treated with chlorine. The State Lab does not test for sulfide. 
  • If the bathroom fixtures are stained by the water, check for the following metals:
    • Blue or green stains indicate the presence of copper
    • Red or rust-colored stains indicate iron is present
    • Black stains indicate the presence of manganese or zinc
  • Uranium occurs naturally in granite formations, which are found throughout Colorado, especially in the foothills. It can be found dissolved in the waters of wells sunk in these areas.
  • New wells, or ones with an unknown history, should get an initial Deluxe Colorado water testing package to establish a baseline of water quality. Every 3-5 years thereafter, use the General Colorado package, with the Annual Colorado package being done on the off years. Learn about common water testing packages.

Compliance testing

Water providers, wastewater providers, and other businesses who supply water to the public follow a compliance water testing schedule.

The Water Quality Control Division has resources for drinking water compliance.

You will decide what to test for in your water in the next step.