EGLE looks at many different results. The four categories shown on this page (pH, Orthophosphate, Iron, and Chlorine) are main indicators of whether the City's corrosion control treatment is working properly. In 2017 EGLE set required ranges for pH and orthophosphate.
Having a small number of sample results outside the required ranges does not necessarily indicate a problem. This just means the City may need to adjust its treatment to bring the water back into the required ranges. The dataset shown below helps the City of Flint make decisions about the best way to treat the water. If more than one sample is collected per day at a particular location, the average or range of all daily samples may be shown.
 |
pH This is a measure of how acidic or basic the water is. Flint is required to keep the pH between 7.2 and 7.9 to minimize corrosion. |
 |
Orthophosphate
This compound is added to drinking water to prevent metals, such as lead, from leaching from the pipes into the water. Flint is required to keep the orthophosphate residual level between 3.1 milligrams per liter (mg/l) and 3.7 mg/l to minimize corrosion. The term 'residual' refers to the amount of the orthophosphate present in the water. |
 |
Iron
There is no required limit for iron, but iron levels below 0.05 mg/l generally mean the treatment system is working properly. |
 |
Chlorine
Chlorine is added to disinfect the water. Bacteria growth in pipes can make the water corrosive. Flint is required to have detectable chlorine in the water, and keeping the chlorine level above 0.5 mg/l helps prevent bacteria-related corrosion. |
Some data in the table is informational only, and some data shows whether target ranges for pH, orthophosphate, chlorine, and iron are being met.
Other testing that EGLE is doing for the City is Lead and Copper Sequential Sampling.
The following results are for the City of Flint Distribution system.
Download the distribution system monitoring data (expanded dataset)
