Water Quality Notification for Parts of Northwest Philadelphia
Fluctuations in environmental conditions that can impact water quality characteristics led to levels of a disinfection byproduct that were slightly higher than usual in one section of the city. Water remains safe to drink.
In short:
- Quarterly data reported in June pushed the annual running average of a disinfection byproduct slightly over recommended levels.
- The notification only applies to customers in the area shown on the map.
- Water remains safe to drink and there is nothing that customers need to do.
- Any potential health impacts would require consistent exposure to elevated levels over a 70 year period.
PWD maintains a careful balance of using enough disinfection to eliminate harmful microbes and limiting disinfection byproducts that the process leaves behind. We take great care to optimize our treatment processes to stay within regulations and provide reliable, safe, clean drinking water for all Philadelphians.
Quarterly reports of routine water quality test results, issued June 25, 2024, showed an increase in annual average levels of the disinfection byproduct Trichloroacetic acid (TCAA). This exceeded a guideline set by the Environmental Protection Agency (EPA) called a Lifetime Health Advisory Level. The state requires a notification if the average level exceeds this guideline of 0.02 parts per million, or “0.02 mg/L” for short. The impacted area showed an average value of 0.0252 mg/L.
What area of the city was impacted?
The test results apply to a section of North and Northwest Philadelphia that receives water from the Baxter Water Treatment Plant. The impacted portion of this service area is shown in the map belowon the right.
Are there any health effects for this situation?
The levels we found have no acute health effects. Health warnings about TCAA are based on longer exposure to higher levels: Potential health effects would require drinking 2 liters of water with elevated levels of TCAA every day for 70 years.
Is there anything the public should do?
There is nothing you need to do. You do not need an alternative water source and you do not need to boil your water. You can continue to use your water as always. However, if you have a specific health concern, please consult your doctor.
How did PWD learn of the increased levels?
PWD monitors for disinfection byproducts (including TCAA) every month at sixteen locations throughout the city. To determine if TCAA is above the regulatory targets, we first calculate the quarterly average of all monthly samples collected in a single quarter. Then we calculate the average of the last four quarterly average values to determine the Locational Running Annual Average (LRAA). If the LRAA value over the last four quarters is greater than 0.025 mg/L, which rounds to 0.03 mg/L, then it exceeds the targets. The last four quarter averages at the sample location that exceeded the targets are shown as follows:
| Trichloroacetic Acid (TCAA) results from Sample Location 1601 | ||||
|---|---|---|---|---|
| 2023 Q3 Quarterly Average | 2023 Q4 Quarterly Average | 2024 Q1 Quarterly Average | 2024 Q2 Quarterly Average | Locational Running Annual Average |
| 0.0335 mg/L | 0.0263 mg/L | 0.0173 mg/L | 0.0237 mg/L | 0.0252 mg/L |
How are we responding?
First, PWD closely monitors the total organic carbon levels in our source water. As levels increase, we increase the amount of powdered activated carbon (PAC) that we add. PAC allows us to remove a large amount of the organic matter in the water, thereby reducing the amount that is left to react with the chlorine.
Second, PWD closely monitors its chlorine, disinfection byproduct (DBP), and DBP precursor levels. We adjust chlorine levels throughout the water treatment process to balance the amounts needed for proper disinfection while minimizing DBP precursors and the DBPs that are formed as a result.
We’re also planning for long-term solutions. To further reduce levels of disinfection byproducts, we are planning to upgrade our drinking water treatment plants. Our Water Revitalization Plan proposes upgrades to all three of our drinking water treatment plants.
For more, go to water.phila.gov/revitalization
What happens next?
We continue to monitor levels of disinfection byproducts including TCAA. To further reduce the amounts of these chemicals, we’re planning upgrades to our Water Treatment Plants. Our Water Revitalization Plan proposes upgrading all three of our water treatment plants over the next 25 years. Upgrades to treatment technologies in our plants can help minimize disinfection byproducts, including TCAA. We’ll inform the public if the next round of test results exceeds targets.