Interpreting Chlorine Results

Interpreting results of the chlorine test:

The detection range of the free chlorine test is 1-10 ppm. Free chlorine results are expressed in parts per million (ppm), which is a standardized unit to describe small concentrations in water. Pool and drinking water treatment requires the maintenance of 1-2ppm of chlorine in the water. For shock treatments, a higher concentration of 4 ppm is required. For hot tubs, the limits are 1-4 ppm for ongoing treatments and 4-10 ppm for shock treatment. Furthermore, by the CDC’s standards, drinking water cannot have chlorine levels higher than 4 ppm (https://www.cdc.gov/healthywater/drinking/public/water_disinfection.html). 

The results of your free chlorine test can be interpreted in the following ways depending on the water source being tested: 


Range Interpretation Treatment Recommendation
< 1 ppm Free chlorine level is below the detection limit. Chlorine level is safe for treated drinking water. Higher concentrations are required for treatment of pools, hot tubs and drinking water. 

Maintain on-going testing and your current treatment plan.

1-2 ppm Free chlorine level is low. Chlorine level is safe for treated drinking water. Chlorine level is sufficient for pool and drinking water treatment, but not for shock treatment. 

Higher concentrations are required for treatment of hot tubs. 

Maintain on-going testing and your current treatment plan.
2-4 ppm Free chlorine level is moderately high. Chlorine level is approaching the safety limit for drinking water.Concentration is sufficient for shock treatments of pools and drinking water. 

Chlorine level is also sufficient for hot tub ongoing treatment.

Maintain on-going testing and your current treatment plan. Consider taking action to dechlorinate treated drinking water. 
4-10 ppm Free chlorine level is moderately high.Chlorine concentration is above safe levels for drinking water. Do not drink water from this source.Chlorine level is too high for pool or drinking water treatment.

Chlorine level is sufficient for shock treatment of hot tubs.

Immediate dechlorination is required. Perform treatment and retest over time. 
> 10 ppm Free chlorine level is high.Chlorine concentration is above safe levels for drinking water or water treatment. Do not shower in, swim in, or drink from this source. Immediate dechlorination is required. Perform treatment and retest over time. 

For recommended treatment plans, see the following help article: https://exactblue.helpscoutdocs.com/article/34-treatment-options-and-recommendations

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