Perchlorate in Rockland Water: Clarkstown System Sampling and Residential Treatment Notes

Overview of Water Supply and Perchlorate Data in Clarkstown

The public water system serving Clarkstown in Rockland County, NY, is sourced from surface water and managed by United Water New York. This system supplies approximately 270,000 people through over 56,000 service connections. Between 2001 and 2005, the EPA conducted an Unregulated Contaminant Monitoring Rule (UCMR1) survey to measure perchlorate among other constituents.

Sampling Scope and Interpretation of Perchlorate Results

The perchlorate results for the Clarkstown supply are based on 65 samples collected over nearly two years. None of these samples showed perchlorate detections above the reporting level of 4.0 micrograms per liter (µg/L). It is important to understand that detections below a reporting level do not indicate the absence of perchlorate; rather, the monitoring instruments did not measure perchlorate above that threshold. Additionally, no federal maximum contaminant level (MCL) for perchlorate currently exists, so the data do not reflect violations or unsafe conditions but serve as a factual basis for understanding perchlorate presence in this water system.

Matching Treatment Capacity to Household Water Use

When existing household water treatment equipment has failed, sizing new treatment depends on daily water consumption and water quality parameters. Residential water use varies by household size, number of bathrooms, and typical water-consuming activities. For example:

• Smaller households (1-3 people) generally use less water daily than larger families.
• Seasonal or weekend homes often have lower continuous demand but may require treatment considering periods of inactivity.

Treatment capacity for perchlorate removal must accommodate peak daily volumes to ensure consistent performance and avoid untreated water bypass.

Adapting Treatment for Household Variations and Property Types

Large households or those with frequent guests may experience higher water use, which demands treatment equipment capable of handling increased flow and volume. Second homes or properties used seasonally often have fluctuating water demand and may require equipment that remains effective after periods of no use and can resume operation with minimal intervention.

Stepwise Approach to Identifying Perchlorate Issues

If perchlorate treatment is a consideration following equipment failure, take a layered approach to confirm water quality and treatment needs:

• Start with the public water system data to understand the regional perchlorate presence; for Clarkstown, no perchlorate above 4.0 µg/L was detected in EPA monitoring.
• Conduct specific water testing at the residence using a certified laboratory to quantify perchlorate levels since area data do not specify individual well or tap water concentrations.
• Evaluate household water use patterns and daily volume to select appropriate treatment capacity.

Additional Considerations for Commercial or Industrial Users

While this briefing focuses on residential water treatment, commercial and industrial operators must consider regulatory compliance, process water quality requirements, and potential multiple contaminant interactions. These factors influence treatment system specifications and operational protocols that go beyond typical household needs.

Conclusions and Common Misunderstandings

It is important not to conclude that absence of perchlorate detections above 4.0 µg/L in Clarkstown’s public water system means all individual residences will have the same perchlorate levels. Individual water quality can vary due to plumbing, local distribution, or private well sources. Furthermore, detection below the reporting limit is not the same as no presence, nor does it indicate safety or health risk by itself. Confirming perchlorate concentration through specific testing of household water is essential before selecting treatment.

After failure of existing treatment equipment, the Fleck Perchlorate Filter ships ready to configure for residential water treatment. This system is designed to reduce perchlorate in household water, matching treatment capacity to daily demand and adapting to residential water use patterns. It provides a documented solution responsive to local water quality and household needs.

Where this information comes from

Source: EPA SDWIS public water system record. Sampled 2003-06-25. These figures describe the public water system's record, not the plumbing inside any individual building.

On record: EPA UCMR1 monitoring (2001-2005) for UNITED WATER NEW YORK (NY4303673), NY: 65 results across 1 listed contaminants, 0 detections above the reporting level; nothing detected above the method reporting level