Recycling Treated Municipal Wastewater for Industrial Water Use

Setback Distances
Appendix B
Status of Water Reuse Regulations and Guidelines
Many states have established setback distances between reclaimed water use areas and
surface waters, potable water supply wells, or areas accessible to the public. Setbacks
are usually required where reclaimed water is used for spray irrigation, cooling water in
towers, and other areas where spray or mist is formed. Setbacks may also be required at
irrigation or impoundment sites to prevent percolated reclaimed water from reaching
potable water supply wells. Setback distances vary depending on the quality of
reclaimed water, type of reuse, method of application, and purpose of the setback, e.g.,
to avoid human contact with the water or protect potable water sources from
contamination. Setback distances, where required, vary considerably from state-to-state,
and range from 50 feet to as much and 800 feet. Some states do not require setback
distances from irrigated areas to areas accessible to the public if a high level of treatment
and disinfection is provided.
Cross Connection Control
Cross connection control regulations to prevent interconnecting reclaimed and potable
water pipelines are included in some state water reuse criteria. Regulations often
address: identification of transmission and distribution lines and appurtenances via
color-coding, taping, or other means; separation of reclaimed water and potable water
lines; allowable pressures; surveillance; and backflow prevention devices. At use areas
that receive both potable and reclaimed water, backflow prevention devices are usually
required on the potable water supply line to each site to reduce the potential of
contaminating the potable drinking water system in the event of a cross-connection at a use
area. Direct connections between reclaimed water and potable water lines are not allowed
in any state.
California’s Water Recycling Criteria require compliance with the California
Department of Health Services cross connection control regulations [State of
California, 2000b]. Those regulations require that water systems serving residences
through a dual water system that uses reclaimed water for landscape irrigation must,
as a minimum, be protected by a double check valve assembly backflow preventer.
The same requirement applies to a public water system in buildings using reclaimed
water in a separate piping system within buildings for fire protection. A reduced
pressure principle backflow prevention device is required as a minimum to protect the
potable system at sites other than those mentioned above. An air gap separation is
required where a public water system is used to supplement a reclaimed water supply.
California’s criteria for dual plumbed systems within buildings include the following
requirements:
Internal use of reclaimed water within any individually-owned residential unit,
including multiplexes or condominiums is prohibited;
Submission of a report that includes a detailed description of the intended use area,
plans and specifications, and cross connection control provisions and testing
procedures;
Craddock Consulting Engineers B-13
In Association with CDM & James Crook
WWReuse Tm1_Appendix B_Regulatory.doc