Recycling Treated Municipal Wastewater for Industrial Water Use

Appendix B
Status of Water Reuse Regulations and Guidelines
NTU at any time. Where membranes are used in lieu of media filtration, turbidity
cannot exceed 0.2 NTU more than 5 percent of the time within a 24-hour period and
cannot exceed 0.5 NTU at any time.
Coliform Bacteria Limits
Most states use fecal coliform organisms as the indicator organism for microbial
pathogens in reclaimed water, while a few states use total coliform. Fecal or total
coliform limits depend on use of the water and are highly variable among states.
Arizona, Florida, and some other states’ regulations are similar to, or based on, the EPA
Guidelines for Water Reuse and use fecal coliform organisms as the indicator organism. In
those states regulations typically require that reclaimed water have no detectable fecal
coliform/100 ml for high level nonpotable applications and not exceed 200 fecal
coliform/100 ml for uses where human contact is minimal.
States that use total coliform as the indicator organism require that total coliform
organisms not exceed 2.2/100 ml for high level uses and either 23 or 240/100 ml for uses
where there is no or minimal human contact with the water. Higher single sample
maximum coliform limits are allowed in several states. Regulatory compliance varies in
different states, but usually is based on median or geometric mean values over a given
time period. Coliform samples are usually required to be collected on a daily basis
during peak flow conditions to represent the most demanding treatment facility
operating conditions. Less frequent coliform sampling is allowed in some states.
Several states require that coliform analyses be conducted using the multiple tube
fermentation technique with the results expressed as the most probable number (MPN),
while others allow use of the membrane filter (MF) technique. A few states do not
specify which enumeration technique to use, and some states allow the use of either the
MPN or MF methods.
The draft revisions of the Minnesota water quality standards include Escherichia coli (E.
coli). While indicator organisms in water reuse criteria do not necessarily have to be the
same as those in waste discharge requirements, it is likely that E. coli will be part of the
evaluation of water reuse criteria for Minnesota.
Limits and Monitoring for Pathogenic Protozoa
At present, no states have set limits on pathogenic organisms for any nonpotable reuse
application, but at least two states require monitoring for specific pathogens under
certain circumstances. In an effort to learn more about the possible presence of
protozoan pathogens in reclaimed water that receives tertiary treatment and a high level
of disinfection, Florida’s reuse rules contain parasite monitoring requirements. Facilities
(ith capacities of 1.0 mgd and larger are required to sample their reclaimed water for
Giardia and Cryptosporidium at least once every two years. Smaller facilities must sample
at least once every five years. Samples are required to be taken following the
disinfection process.
California requires that reclaimed water used for nonrestricted recreational
impoundments be monitored for enteric viruses, Giardia, and Cryptosporidium if tertiary
Craddock Consulting Engineers B-10
In Association with CDM & James Crook
WWReuse Tm1_Appendix B_Regulatory.doc