The North Tahoe Public Utility District is responsible for protecting the public water supply from contamination or pollution as a result of the backflow of contaminants or pollutants through the customer’s water service connection. The cross-connection control program is mandated by the State of California Department of Health Services.
To ensure our water supply is protected from cross-connections, District staff reviews construction plans for potential cross-connections, conducts field inspections of properties for potential cross-connections, inspects the installation of backflow prevention assemblies, monitors the operation of existing assemblies by requiring annual testing and conducts customer education on the importance of cross-connection control.
Backflow prevention assemblies must be tested annually, at a minimum, by an NTPUD approved certified Backflow Prevention Assembly Tester. You will receive a notice from the District in advance of the test due date. The following links provide you with our list of certified testers that you may hire and our current test report that we request the testers to use but is not required if they have their own company form that follows the format of ours.
NTPUD Approved Certified Backflow Testers – 6/2019
NTPUD Backflow Assembly Test Form and Maintenance Report
NTPUD Water Ordinance – Chapter 9
NTPUD Ordinance Attachment: Technical Specifications – Chapter 7
For More Information
For more information about our cross-connection control program, contact Ken Fischer at (530) 546-4212 or view the frequently asked questions below.
Approved Backflow Assemblies
The USC Foundation for Cross-Connection Control and Hydraulic Research
AWWA Backflow Prevention Resource Community
The American Backflow Prevention Association
US EPA Cross-Connection Control Manual
USC Cross-Connection in Household Plumbing Brochure
A cross-connection is an actual or potential connection between a public water system or consumer’s potable (drinking) water system and any source or system containing non-potable water or other substances. (Non-potable water is water that is unfit or unsafe to drink.)
There are two conditions that can cause backflow:
1. Back-siphonage – occurs due to a loss of pressure in the public water system providing your water. This can be caused by a rapid withdrawal of a high volume of water from the system due to a system shutdown, a break in the supply mains, or active fire protection. This reduction of pressure creates a vacuum in the piping which draws water back into your home from your irrigation lines, hot tub, or any plumbing fixture with a submerged inlet. These sources of water can contaminate your home’s drinking water and even enter the public system contaminating others’ potable water.
2. Backpressure – is created when the source of pressure, such as a household pump, creates pressure greater than that supplied through the public water system. A pump from a landscape pond, pool, hot tub, hydronic heating system, fire sprinkler system or other system containing non-potable water, pumps that water into the potable water supply affecting your home, and even the entire public drinking water system.
A backflow prevention assembly is a mechanical device that prevents water from “backflowing” into a potable water system (either the consumer’s internal system, the public water system, or both).
Yes, there are several different types of backflow prevention assemblies, which are listed below:
• Air Gap (AG)
• Reduced Pressure Principle Backflow Prevention Assembly (RP)
• Double Check Valve Backflow Prevention Assembly (DC)
• Pressure Vacuum Breaker (PVB)
• Atmospheric Vacuum Breaker (AVB)
• Spill-Proof Pressure Vacuum Breaker (SVB)
The North Tahoe Public Utility District (District) recognizes all of these as acceptable forms of cross-connection control. However, each assembly must be approved prior to installation to ensure that the assembly is on the approved list and that the type of assembly used shall be based on the existing or potential degree of hazard.
After the installation has been inspected and approved, the assembly must be tested. Per California State Law, all backflow prevention assemblies must be tested upon installation. A District-approved, certified Backflow Prevention Assembly General Tester must test the assembly to ensure that it is operating correctly and will complete the District’s “Backflow Prevention Assembly Test Report”, available on our website or at our office. The tester will then mail, fax, or email the completed form back to the District.
1. A Pollutant – is any substance which affects the aesthetic quality of the water (taste, color or odor), but does not pose a health hazard.
2. A Contaminant – may cause illness or death when ingested, and is considered to be a health hazard. Some common examples of hazards or systems requiring backflow prevention assemblies are:
• Fire Sprinkler Systems
• Hydronic Heating Systems
• Irrigation Systems
• Boilers/Water Heat Exchangers
• Auxiliary Water Supplies (e.g., lake intakes, wells)
When there is an auxiliary water supply on a property, it can be a potential cross-connection if that auxiliary supply accidentally gets connected to the public drinking water supply. For example, if your property has a lake intake or a private well that feeds your irrigation system, but your irrigation system is also fed from the public water system, the water from the auxiliary supply could get into the public drinking water system. For properties with an auxiliary water supply, the District requires an approved backflow prevention assembly to be installed at the meter.
In general, the District has taken the approach of requiring internal protection with regards to the installation of backflow prevention assemblies, in order to protect the drinking water within the property as well as the public water system. This approach has been determined to be the best method for the protection of public health and safety. Furthermore, requiring internal protection, at the point of potential cross-connection, typically allows our customers to install smaller backflow prevention assemblies within their structure, and generally eliminates the need to house these assemblies in an above-ground, continually heated enclosure.
These can be a potential cross-connection if the stop and waste valve is installed below the ground surface; the water (including any contaminants, such as chemicals, dirt, bacteria, fertilizer, etc.) can pool up and then enter your internal plumbing and potentially the drinking water system through the valve when it is opened back up.The California Plumbing Code and the District requires that “Combination stop-and-waste valves…shall not be installed underground.”
A yard hydrant can be a potential cross-connection through the drain hole; when a back-siphonage condition occurs, contaminants (such as chemicals, dirt, bacteria, fertilizer, etc.) can potentially enter your internal plumbing and the public drinking water system through the drain hole.
The District requires that yard hydrants have an RP assembly installed upstream of them, or that they are replaced with a sanitary yard hydrant. A sanitary yard hydrant still has a drain hole, but the water drains into a sealed tank. When the hydrant is turned on again, the water in the tank is expelled; there is no cross-contamination with the yard hydrant and the soil.
For approved sanitary yard hydrants, contact the District.
For more information:
• Visit our website, at www.ntpud.org/bfp
• View the District’s Water Ordinance at http://ntpud.org/sites/default/files/docs/general/NTPUD%20Water%20Ordina…
• For any other questions, please use the following contact information:
Michael D. Warren
Lead Water Quality Control Technician
North Tahoe Public Utility District
530-546-4212 ext 5452