1. Direct Cross-Connection (a) A Clean-In-Place system is used to direct sanitizer from a reservoir to a recently cleaned milk tank. The sanitizer exists the tank and flows back to the reservoir. Sanitizer concentration is maintained by adding concentrated sanitizer to the tank and a metering pump is used to add potable water as needed.
Potable water supply
Milk tank
Return flow to reservoir
Pressurized flow to tank
Concentrated
sanitizer
Sanitizer reservoir
Metering
Pump

2. Direct Cross-Connection (b) A sudden drop in the pressure in the potable water line or an increase in the sanitizer reservoir could cause the sanitizer to backflow into the potable water supply.
Potable water supply
Milk tank
Back-pressure from the pump causes sanitizer to enter the potable water supply
Return flow to reservoir
Pressurized flow to tank
Concentrated
sanitizer
Sanitizer reservoir
Metering
Pump

3. Direct Cross-Connection (c) The solution is to install a vacuum breaker between the metering pump and the potable water supply thus preventing a greater a build-up of pressure on the non-potable side.
Potable water supply
Milk tank
Return flow to reservoir
Vacuum breaker
Pressurized flow to tank
Concentrated
sanitizer
Sanitizer reservoir
Metering
Pump

4. Indirect Cross-Connection (a) Potable water enters a sanitizer mixing tank through a submerged inlet.
Flow to equipment
Submerged water inlet
Fill line
Submerged water inlet
Pump
Potable water supply
Sanitizer mixing tank

5. Indirect Cross-Connection (b) A sudden drop in the pressure in the potable water line causes contaminants to siphon into the potable water supply.
Flow to equipment
Back-siphonage causes sanitizer to enter the potable water supply
Fill line
Submerged water inlet
Pump
Potable water supply
Sanitizer mixing tank

6. Indirect Cross-Connection (c) The solution is to raise the water inlet so that it is always above the surface of the sanitizer thus preventing build-up of pressure gradient and siphonage from occurring.
Flow to equipment
Air gap
Potable water supply
Fill line
Pump
Sanitizer mixing tank