1. Workshop developed by RCAP/AWWA and funded by the USEPA
System Operations:
Cross Connections
Instructors please mention that this is the second of two modules focused on distribution system operations. This module focuses on main breaks and cross connections, and describes how these events can compromise water quality in the distribution system.
Workshop developed by RCAP/AWWA and funded by the USEPA
Developed by American Water Works Association with funds from the U.S. Environmental Protection Agency, Published 2015

2. Cross Connections Cross Connection―
any direct interconnection between a public water
system and a non-public water system or other source which may result in the contamination of the drinking water provided by the public water system….
MS Primary Drinking Water Regulation

3. Cross Connections
The contaminants can be drawn or pushed back into the water distribution system during a backflow event
A dynamic problem since plumbing systems are constantly being installed, altered and extended

4. Cross Connections
“over 100,000 new cross-connections are formed each day” (AWWARF, 2000)

5. Can you find the Cross Connection?
Cross Connections
Can you find the Cross Connection?

8. Cross Connections
“the greatest contributing factor to waterborne disease outbreaks in the U.S.” (AWWARF, 2000)

9. Cross Connections: A Backflow Danger
Backflow: The flow of water or other liquids, mixtures or substances into the distribution pipes of a potable water supply from any source other than its intended source.
Two causes of backflow
Backsiphonage
Backpressure 9

10. What Causes Backflow? Backsiphonage
A reversal of the normal direction of flow in the line due to a negative or reduced pressure in the supply line.
Non-potable fluids (contaminants) can be sucked into the distribution system
Low pressure can be caused by line break, fire fighting, pump failure, flushing and others 10

12. Cross Connections: Backsiphonage
Maryland
A herbicide entered the distribution system
Cross connection between the herbicide holding tank and the potable water supply line
USEPA, Cross-Connection Control Manual 12

13. Cross Connections: Backsiphonage
Pennsylvania
Low pressure in the supply line due to a line break
Chlordane and heptachlor entered the distribution system through a cross connection (a hose immersed in a chemical tank)
USEPA, Cross-Connection Control Manual 13

14. What Causes Backflow? Backpressure:
Pressure downstream becomes greater than the supply pressure causing a reversal of the normal flow
When a potable water system is connected to equipment or a facility working under a higher pressure, forcing non-potable water into the potable system 14

16. Cross Connections: Backpressure
Private well attached to home
Home attached to public water system

17. Cross Connection Program
Cross Connections Prohibited …..
unless a backflow prevention assembly is
installed between the public water system
and the source of contamination
Cross Connection Control Program
All public water supplies shall adopt and enforce a cross connection control policy or ordinance
Backflow prevention assemblies must be tested by Certified Testers at least annually
Records must be maintained for 5 years

18. Cross Connection Control Devices
Air Gap
Maximum protection
Must be twice the diameter of water supply outlet
USEPA, Cross-Connection Control Manual 18

19. Cross Connection Control Devices
Reduced Pressure Zone Backflow Preventer
Used in high hazard conditions
Can be used under constant pressure
Common installations include carwashes, dry cleaners, funeral homes, hospitals, sewage facilities
USEPA, Cross-Connection Control Manual 19

20. Cross Connection Control Devices
Double Check Valve
Protects against backsiphonage & backpressure
Can be used under constant pressure
Common installations include fire sprinkler systems & multi-story buildings
USEPA, Cross-Connection Control Manual 20

21. Cross Connection Control Devices
Atmospheric Vacuum Breaker
Protects against backsiphonage only
Not designed to protect against back pressure conditions
Commonly used on plumbing fixtures and hose bibs
USEPA, Cross-Connection Control Manual 21

22. What to do in case of a backflow event?
Stop the pressure differential that caused backflow of contamination, if possible
Identify and remove the cross connection
Contact MSDH
If harmful contaminants are suspected, provide immediate notice to the affected customers
Develop and carryout a plan for systematic flushing of the system
Continue to sample within and outside the suspected contaminated area 22

23. What is wrong with this picture?
High Service Pump
Discharge Line
Ask the class to identify the cross connection before sharing the answer:
Hose with no hose bib or vacuum breaker
The open ended garden hose is connected to the high service pump discharge. When the high service pumps are off and there is no pressure in the pipe, if there is flooding on the floor, or if the end of the hose is connected to a tank or bucket, water can flow through the hose into the pump discharge line as there are no breakers. This will result in cross connection and contamination.

24. Online Resources USEPA Cross-Connection Control Manual
USEPA Cross-Connection Control: A Best Practices Guide
ASSE Series 5000, USC's FCCC & HR's "Manual of Cross-Connection Control", or UFL's TREEO's "Backflow Prevention – Theory and Practice" 24

25. Questions?

26. Thank You! Alexander Brandon Jim Miller State Coordinator
Jim Miller
Section Manager
Dinah Foreman
Regional Trainer