The Water Reuse Challenge

As communities across California, Arizona, Texas, Florida, and the broader American West face increasing water scarcity, recycled water has moved from a niche application to a core component of municipal water portfolios. Direct potable reuse (DPR), once a regulatory frontier, is now codified in California’s DPR criteria, and similar frameworks are emerging across the country.

The shift carries a high microbiological burden. Recycled water producers must demonstrate consistent pathogen removal across treatment trains, validate log reduction values for multiple pathogen groups, monitor surrogate and indicator organisms, and document compliance against tightening regulatory criteria.

H₂O Molecular partners with utilities, treatment process designers, engineering consultants, and regulators to provide the microbiological data those programs depend on.

Log Reduction Value (LRV) Verification

Demonstrating that a treatment train consistently achieves required log reductions for viral, protozoan, and bacterial pathogens is the central microbiological task of any potable reuse program. H₂O Molecular supports LRV verification through:

• Influent and effluent pathogen quantification (norovirus GI, norovirus GII, Cryptosporidium, Giardia, adenovirus, enterovirus)
• Surrogate analysis with native and seeded indicators
• Bracketing studies and challenge testing
• Statistical evaluation and regulatory reporting support

Digital PCR is particularly well-suited to LRV work because of its absolute quantification, low limit of detection in finished water, and resistance to matrix inhibition across the treatment train.

Coliphage Analysis (Culture-Based)

H₂O Molecular performs culture-based coliphage analysis, both somatic and male-specific (F+) coliphages, using US EPA Methods 1601, 1602, 1642, and 1643. Coliphages are the most widely accepted viral indicator for water reuse and are referenced in both California Title 22 and federal recycled water frameworks.

Applications include:

• Title 22 compliance monitoring
• Groundwater Rule and LT2 compliance
• IPR and DPR treatment train validation
• Onsite reuse system verification
• Coliphage challenge studies

Viral and Bacterial Indicators

Beyond coliphages, we offer the full suite of indicator and surrogate organisms used in reuse program design and validation:

• PMMoV (Pepper Mild Mottle Virus): a highly persistent human enteric viral surrogate
• crAssphage: a recently characterized human-specific bacteriophage with utility as both an MST marker and a viral indicator
• Total coliforms and E. coli
• Bacteroides markers (HF183 and others): human-source verification

Direct Pathogen Quantification

For programs that require direct pathogen monitoring rather than indicator-based surrogate assessment, we offer dPCR quantification of:

• Enteric viruses: norovirus GI, norovirus GII, rotavirus, adenovirus, enterovirus, hepatitis A
• Protozoa: Cryptosporidium parvum / hominis, Giardia lamblia
• Bacterial pathogens: Salmonella, E. coli O157:H7, Legionella pneumophila

See Resources for the full target list.

Applications & Use Cases

• Title 22 recycled water compliance monitoring: landscape irrigation, agricultural reuse, and industrial reuse
• IPR and DPR program development and validation
• Treatment train validation and pathogen challenge testing for new technologies (AWPF, RO, UV/AOP, ozone-biofiltration)
• Onsite non-potable water systems (ONWS) monitoring
• Stormwater capture and reuse applications
• Agricultural and food safety reuse applications

Sample Types We Analyze

Raw wastewater · Secondary effluent · Tertiary effluent · MBR permeate · RO permeate · UV/AOP effluent · Advanced treatment finished water · Engineered storage buffer water · Distribution system samples

Who We Work With

Water utilities operating recycled water programs · Engineering consultants designing reuse facilities · Treatment technology vendors validating new processes · State and federal regulators · Onsite reuse program managers · Agricultural and industrial reuse users