An impact assessment for urban stormwater use

Area of Science:

• Environmental science
• Public health
• Water resource management

Background:

• Stormwater presents a viable non-potable water source, reducing reliance on municipal wastewater and mitigating pollution.
• Addressing public health concerns is crucial for widespread adoption of stormwater collection and use.
• Escherichia coli (E. coli) is a key indicator of fecal contamination in urban stormwater, relevant to human health risk assessments.

Purpose of the Study:

• To assess human health risks associated with using stormwater for various non-potable applications.
• To evaluate the impact of E. coli levels in stormwater on different usage scenarios.
• To identify applications requiring specific risk management strategies.

Main Methods:

• Utilized a source-pathway-receptor model to evaluate exposure likelihood and impact magnitude.
• Assigned risk scores (0-5) for occupational and non-occupational stormwater applications.
• Compared median stormwater E. coli concentrations with established guideline levels for different uses.

Main Results:

• Most stormwater applications presented low to medium human health risks based on E. coli levels.
• Domestic car washing and occupational irrigation of edible crops showed the highest predicted risks.
• Median E. coli levels in stormwater exceeded guidelines for specific high-risk applications.

Conclusions:

• Stormwater reuse is generally safe for many non-potable uses, provided quality is monitored.
• Specific applications, like irrigating food crops and car washing, necessitate targeted risk reduction measures.
• Implementing remedial actions is essential for high-risk stormwater uses to ensure public safety.