HomeMy WebLinkAbout2026.04.02 Item 9a Attachment - Staff ReportProtecting Public Health Through
Backflow Prevention and Hazard Control
Construction Standard Update
Stop & Drain Valve
Above-Ground
Installation
Requirement
Cross-Connection Control & Backflow Prevention Program | April 2026
A Common Practice in Our Service Area
A Cross-Connection is any actual or potential link between the District’s drinking water supply and a
source of contamination.
Burying stop & drain valves is very common in the South Lake Tahoe area —and for good reason. It's an
effective way to drain a home's plumbing before winter.
Why It's Used
•Drains the water service line to prevent freeze
damage in winter
•Simple, inexpensive installation during new
construction
•Allows full drainage of the home before
seasonal shutdown
•Has been standard practice in cold-climate
areas for decades
Why It's Not Safe
•Buried valves can become submerged in
contaminated soil or groundwater
•The waste port opens directly to the
surrounding soil during drainage
•During a backflow event, contaminants can be
drawn directly into the drinking water system
•Creates a cross-connection —a violation of
state drinking water regulations
Why Buried Valves Are a Cross-Connection Hazard
What the diagram shows:
1
The waste port opens to
surrounding soil when the valve
drains
2
Groundwater and soil
contaminants surround the
buried valve
3
During a backflow event, polluted
water is drawn directly into the
service line and into the drinking
water system
This risk exists regardless of whether a backflow event has occurred —the potential for contamination is present any time the valve is buried.
Cross-Connection Control & Backflow Prevention Program
About the Program
STPUD developed and maintains a comprehensive Cross-Connection
Control & Backflow Prevention Program to protect the District's
drinking water supply from contamination.
The program is administered by Ross Cole, Inspection Supervisor —
registered with the State Water Resources Control Board as the
District's Cross-Connection Control Coordinator —supported by a 4
person AWWA certified team.
Currently tracking ~1,800 active backflow prevention assemblies across
the service area, each tested annually.
State Requirement
The State Water Resources Control
Board required all water agencies to
submit Cross-Connection Control Plans
by July 1, 2025.
STPUD's Response
STPUD developed and submitted its
plan on time. Today's update is one
proactive step already being taken
under that program.
What's Next:The plan is currently awaiting full SWRCB approval. Once approved, staff will return to the board to present
the plan in depth and move toward formal adoption —continuing our commitment to keeping District water
clean and safe.
The Construction Standard Change
CURRENT PRACTICE
•Stop & drain valves buried underground at
time of installation
•No above-grade requirement on new
construction
•Cross-connection risk present and
unmitigated
•Existing installations remain in place
➜
NEW STANDARD
•Stop & drain valves on new construction must
be installed above ground
•Stop & drain valves are still permitted —just
not buried
•Aligns with UPC Section 605 and SWRCB
cross-connection policy.
•Aligns with Tahoe City PUD & North Tahoe
PUD’s Cross Connection Program.
•If burial is desired, an appropriate backflow
device must be installed upstream of the
valve to protect STPUD water system.
Next Steps
As part of STPUD's ongoing effort to keep District water clean and safe from contaminants:
1 Press Release —Public notification of the updated construction standard going out to the
community.
2 Contractor
Workshop —
Staff will host a contractor and plumber education workshop in the boardroom —
end of April.
3 Full Plan
Presentation —
Once SWRCB approval is received, staff will return to present to the board, the
Cross-Connection Control Plan in depth and move toward adoption.
Questions?