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Environmental Laboratory

Photos of Water.

The United States has one of the safest water supplies in the world. The US Environmental Protection Agency sets and enforces standards for the public drinking water supply, while individual states do so for private drinking water wells. Recent rains followed by flooding in certain parts of Delaware and around the country have raised concerns about the quality and safety of our drinking water. Because drinking water quality varies from place to place depending on the condition of the water source and the treatment it receives, the best source of specific information about your drinking water is your water supplier.

Water suppliers that serve the same people year-round are required to send their customers an annual water quality report – a consumer confidence report.

Private well owners are responsible for testing their water. They may contact private commercial laboratories certified to test drinking water quality or the Delaware Public Health laboratory (DPHL). It is recommended to test private well water annually for nitrates and coliform bacteria. More frequent testing, however, may be needed if a problem is suspected.

Consumers of public water systems are not responsible for getting their water tested. The DPHL under EPA mandate regularly tests public water systems through the Office of Drinking Water. In addition to testing for coliform bacteria and nitrates, public water systems are tested for a number of contaminants, including pesticides and trace metals.

Drinking Water Requirements for States and Public Water Systems | US EPA

Excessive levels of these contaminants in our drinking water may cause serious illness and sometimes death in children, the elderly and the sick.

National Primary Drinking Water Regulations including Maximum Contaminant Levels | Ground Water and Drinking Water | US EPA

Types of Drinking Water Contaminants | Drinking Water Contaminant Candidate List (CCL) and Regulatory Determination | US EPA

Secondary Drinking Water Standards: Guidance for Nuisance Chemicals | Drinking Water Contaminants – Standards and Regulations | US EPA

How do I get my water tested if my home is not supplied by a Public Water system?

Private well water owners may pick up a sample form and bottle from a county office (New Castle County, Kent County, Sussex County) or the DPHL for a cost of $2.00 each for a bacterial and chemical test. Follow the directions given and return in a timely manner to the office where you received the bottle. The sample may be rejected if directions are not followed or the form is unreadable.

DPHL analyze for presence or absence of total coliforms/Escherichia coli for bacterial sample and Nitrite, Nitrate, Fluoride, Chloride, Sulfate, Iron, Calcium for Hardness, Sodium, pH, and alkalinity for a chemical sample. DPHL does not test private drinking water wells for non-prescribed chemical or bacterial contaminants unless the DE Office of Drinking Water submits the sample to the laboratory. Homeowners must contact the Office of Drinking Water or a private laboratory for this additional testing. For a list of laboratories certified to conduct drinking water testing, contact the Office of Drinking Water.

Drinking Water – Private Well Owners

How do I receive results? What if they are elevated?

It takes approximately one week for the bacterial results and three weeks for the chemical results to be available. Results are sent to the appropriate county unit (private well samples) and the Office of Drinking Water (public water supply samples.) Please do not contact the lab for results.

The county health unit will then mail the test results to the private well owner. If elevated levels of contaminants are found, they will include information such as when to re-test and prevention measures such as boiling water or using bottled water.

The Office of Drinking Water sends public water test results, conducted by DPHL, to water suppliers, who are required to notify customers quickly when contaminants are found. Otherwise, reports are sent out annually.

Drinking Water Notices

Where Can I Get More Information About Private Wells?

For more information on the quality of private well drinking water, visit the EPA.

Private Well Water Collection Forms and Instructions

For additional information refer to the following links:

Bacteriological Laboratory

Chemistry Laboratory

Drinking Water Tests at the Delaware Public Health Laboratory

The Milk Safety Program

Wastewater Surveillance Program

Return to the Delaware Public Health Laboratory home page.

This page was last updated 12/23

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