Delaware Bay at Sunset
State of Delaware / Environment / Private Drinking Water (Wells) /

Get your water tested every year.

It is very important that private wells are inspected and water tested once a year (and more frequently under certain conditions) to ensure the water is safe to drink. Presence of contaminants in one well does not necessarily mean contaminants are present in neighboring wells. Groundwater quality can be affected by many factors including well depth and water source (aquifer). Data presented for the selected geography serve as an indicator of possible contaminants that may be present in nearby wells.

Learn how to test your water

The private drinking water data below are based on tests conducted at the Delaware Public Health Laboratory. Testing only includes basic, minimal requirements to evaluate drinking water quality. The contaminants for testing were chosen to provide the most cost-effective method for private well owners to have the information necessary to take feasible corrective actions that could address drinking water quality. The amount of tests are insufficient in numbers to make conclusions about the entire state. A large quantity of similar and additional tests are also conducted at independent laboratories.

The entire picture of water quality cannot be determined solely from reviewing the data below. The best way to determine if your private well water meets the basic, minimal standards for drinking is to have it tested.

Select Contaminants

Health-Related Contaminants

E. coli

2018 - 2,083 wells tested
1.03
% tested positive

Fluoride

2018 - 2,083 wells tested
MCL 2.0 mg/l
0.1
mg/l
Normal
less than 1.3mg/l
Borderline
between 1.3mg/l and 2.0mg/l
High
over 2.0mg/l

Nitrate (NO3)

2018 - 2,083 wells tested
MCL 10.0 mg/l
4.4
mg/l
Normal
under 10mg/l
High

Total Coliforms

2018 - 2,083 wells tested
14.45
% tested positive

Aesthetic-only Factors

Chloride

2018 - 2,083 wells tested
MCL 250.0 mg/l
14.4
mg/l
Normal
under 250mg/l
High

Iron

2018 - 2,083 wells tested
MCL 0.3 mg/l
0.1
mg/l
Normal
under 0.3mg/l
High

Sodium

2018 - 2,083 wells tested
MCL 200.0 mg/l
11.2
mg/l
Low
under 20mg/l
Medium
between 20mg/l and 200mg/l
High
over 200mg/l

Sulfate

2018 - 2,083 wells tested
MCL 250.0 mg/l
5.3
mg/l
Normal
under 250mg/l
High

Water Hardness

2018 - 2,083 wells tested
MCL 181.0 ppm
18.4
ppm
Soft
under 60ppm
Moderately Hard
between 60ppm and 180ppm
Very Hard
over 180ppm

Detailed Contaminants Reports