What Quality is Fairfax County Water with Respect to 1,2,3-TCP?
If you are wondering about 1,2,3-trichloropropane (often called 1,2,3-TCP or TCP) in Fairfax County household water, it’s useful to know what the EPA’s monitoring data shows. Fairfax County Water Authority’s system, serving over a million people with surface water, had no detections of 1,2,3-TCP above the reporting level of 0.03 micrograms per liter (µg/L) during federal monitoring from 2013 to 2015. There is no federal maximum contaminant level (MCL) established for this chlorinated solvent in this system, and no health-based violations have ever been recorded for any contaminant.
Granular Activated Carbon Contact Time: Why Bed Depth Matters More for TCP than for Taste
The effectiveness of granular activated carbon (GAC) in treating TCP depends heavily on contact time, which is largely determined by the bed depth of the carbon filter. Unlike compounds related mainly to taste or odor, TCP molecules require longer interaction with carbon to be adsorbed effectively. Deeper beds extend this contact time, increasing the likelihood that TCP molecules bind to the carbon. For households considering treatment options, systems designed to optimize bed depth for TCP can provide more reliable reduction of this specific chlorinated solvent compared to those primarily targeting aesthetic issues.
Why the Reporting Level for this Solvent is Thousands of Times Lower than for Common Metals
The reporting level of 0.03 µg/L for 1,2,3-TCP is much lower than typical thresholds used for many metals because TCP is a synthetic chlorinated solvent with different chemical behaviors and health considerations. While metals often have established maximum contaminant levels based on decades of regulation, TCP has no federal MCL, so monitoring uses a low reporting level to detect its presence even at trace amounts. This allows regulators and consumers to better understand its occurrence, even though detections are not violations or safety warnings.
What 'Detected', 'Median' and 'Range' Mean in the Sampling Record on This Page
The EPA’s data from public water system monitoring uses terms to describe measurements of contaminants. 'Detected' means the instrument measured the compound at or above the reporting level; however, no detection occurred above 0.03 µg/L in Fairfax County’s records for TCP. 'Median' would represent the middle value if detections occurred, and 'range' would show the spread between the lowest and highest detected values. Since no detections were reported in this system, these statistical measures indicate the absence of measurable TCP rather than quality concerns.
How to Judge Treatment Capacity Against the Household's or Facility's Daily Demand
When selecting a method to address potential TCP in household water, it is critical to consider the volume of water used daily. Treatment capacity must match or exceed the household's water usage to maintain effectiveness. For example, a larger family or higher daily flow requires systems with adequate filter bed size and flow rate capabilities to ensure sufficient contact time. Understanding your average daily water consumption helps in choosing a system designed to maintain TCP treatment without compromising household supply.
How Public-System Records Differ from Private-Well Testing in What They Establish
The public water system records reflect water quality as measured at the system level, covering a broad service area including Fairfax County. They do not measure the water at an individual home’s tap or private well. Private wells can have very different water quality profiles, so testing your own water is essential. Public system records are useful for understanding regional water quality trends but cannot replace specific testing to determine the TCP concentration in your household water.
What Changes for a Large Household, a Second Home, or a Seasonal Property
Household size and usage patterns affect the choice of treatment approach for TCP. A large household needs equipment that can handle higher daily volumes without reducing treatment effectiveness. For a second home or seasonal property, periods of low or intermittent use require equipment that can maintain performance despite changes in flow and demand. Systems shipped ready to configure for flexible deployment can accommodate these differing needs without compromising the treatment of TCP.
Closing: The Single Test to Settle Your 1,2,3-TCP Treatment Decision
To determine the necessity and type of treatment, the key step is to obtain a water analysis specifically testing for 1,2,3-trichloropropane in your home's water supply. This test should quantify TCP concentration in micrograms per liter (or parts per billion). A result showing TCP below the detection limit used in regional monitoring confirms the minimal presence suggested by Fairfax County data, potentially reducing the urgency for treatment. If TCP is detected, choosing a treatment solution such as the C-Series 1,2,3-TCP Filter, designed for optimal granular activated carbon contact time, can provide targeted management tailored to your household’s water demand.
Where this information comes from
Source: EPA SDWIS public water system record. Sampled 2014-04-14. These figures describe the public water system's record, not the plumbing inside any individual building.
On record: EPA UCMR3 monitoring (2013-2015) for Fairfax County Water Authority (VA6059501), VA: 20 results across 1 listed contaminants, 0 detections above the reporting level; nothing detected above the method reporting level