Plumbing Overview Plumbing and Cross Connection Control Plumbing shall be sized and installed according to applicable codes There shall be no cross connections between the potable water supply and any nonpotable or questionable water supply. Where nonpotable water systems are permitted for purposes such as air conditioning and fire protection, the nonpotable,, water must not contact, directly or indirectly, food, potable water, or equipment that contacts food or utensils. The piping of any nonpotable water system shall be durably identified so that it is readily distinguishable from piping that carries potable water. 9/24/2007 1 9/24/2007 2 Water Supply System 2 Components: Potable Water Supply Waste System Cross-Connection Connection Any actual or potential physical connection between a public water system or the consumer's water system and any source of non-potable liquid, solid, or gas that could contaminate the potable water supply by backflow. 9/24/2007 3 9/24/2007 4 Contamination of the Potable Water Supply May Occur if: The potable water supply piping is not protected (or is improperly protected) from a cross connection; A physical cross connection is not made between the potable water supply piping and a contaminant source; and Backflow conditions occur. Backflow The undesirable reversal of flow of water or other substances through a cross connection into the public water system or consumer's potable water system. The flow of water (or other solid, liquid, or gas from any source) back into the potable water supply. Is caused by either back pressure or back siphonage 9/24/2007 5 9/24/2007 6 1
Backpressure Backflow caused by pressure in the customer's plumbing being greater than the pressure in the water supply piping. The higher pressure in the customer's plumbing may be from a booster pump, heating boiler, etc. Involves a reverse flow of water/substance from a customer's pressurized system into the potable water supply 9/24/2007 7 9/24/2007 8 Backpressure - Example Fire department withdraws water from a hydrant which reduces the pressure in the public water system main from 50 pounds per square inch (psi( psi) ) to 20 psi. A customer served by the public water system has a lawn irrigation system. The customer s s irrigation system is supplied with water from a pond. The pump supplying the irrigation system operates at 30 psi. To ensure a supply for the irrigation system when the pond is dry, the customer installed a standby connection to the household plumbing (potable water piping). On the day of the fire flow situation, the normally closed valve between the household plumbing and irrigation piping is accidentally left open. 9/24/2007 9 Backpressure Example (cont d) On the day of the fire flow situation, the normally closed valve between the household plumbing and irrigation piping is accidentally left open. Backflow wouldn t t normally occur at this customer s connection because the pressure in the public water system is greater than the pressure supplied by the irrigation pump. During the fire flow situation, the pressure from the irrigation pump is greater than the pressure in the water main. Water from the pond is pumped into the household plumbing, and then into the public water system main. When the fire flow ends, pressure in the public water system water main increases, and contaminated water is delivered to customers served by the system. 9/24/2007 10 Backsiphonage Backflow caused by negative pressure (partial vacuum or vacuum) in the supply piping Occurs when system pressure is reduced below atmospheric pressure. The effect is similar to sipping water through a straw. Backsiphonage - Examples In a large fire, a pump is connected to a hydrant causing partial vacuum in water supply system. A nearby unprotected hose is immersed into a mop bucket. The negative pressure caused by the increased water demand caused backflow. 9/24/2007 11 9/24/2007 12 2
Direct Vs. Indirect Cross-Connection Connection A direct cross- connection is subject to backpressure An indirect cross- connection is not subject to backpressure LOW (NON-HEALTH) HAZARDS Pollutants Turbidity, Beverages, Food Coloring (affect odor or color, but no health risk) 9/24/2007 13 9/24/2007 14 HIGH (HEALTH) HAZARDS Contaminants Pesticides, Chemicals, Infectious Microorganisms (could cause illness or death) 9/24/2007 15 HIGH (HEALTH) HAZARDS Lethal Sewage and Radioactive Materials (could cause illness or death of epidemic proportion) 9/24/2007 16 Backflow Prevention Accomplished 2 Ways At the point of a cross-connection, connection, backflow must be prevented by: Air gap (physical separation), or Installation of a backflow prevention device (assembly). 9/24/2007 17 Air Gap Physical separation No direct connection Will protect against both backsiphonage and backpressure Only acceptable means of protecting against lethal hazards 9/24/2007 18 3
Indirect Waste Connection Indirect Waste Indirect waste connection: A A direct connection may not exist between the sewage system and a drain originating from equipment in which food, portable equipment, or utensils are placed. 9/24/2007 19 9/24/2007 20 Indirect Waste - Air Gap Indirect Waste at 3C Sink 9/24/2007 21 9/24/2007 22 Indirect Connection at Dishwasher Indirect Waste 9/24/2007 23 9/24/2007 24 4
Indirect Waste Plumbing at a 3 Compartment Sink Air gap 9/24/2007 25 9/24/2007 26 Air Gap on Lavatory Air Gap and Effective Opening Flood Level Rim 9/24/2007 27 9/24/2007 28 Air Gap Air Gap Air gap Air gap 9/24/2007 29 9/24/2007 30 5
Ice Machine Indirect Waste 9/24/2007 31 9/24/2007 32 Dipper well Air Gap Backflow Prevention Devices Some devices and assemblies are designed to prevent backsiphonage backflow only. Others are designed to prevent both backsiphonage and backpressure backflow. When selecting a backflow preventer to protect the public water system, the purveyor must make sure that the preventer is suitable for the backflow application conditions likely to occur for a particular connection (or fixture). 9/24/2007 33 9/24/2007 34 Backflow Prevention Devices Backflow preventers must also be suitable for the degree of health hazard (high vs. low) posed by the customer s s plumbing system (or fixture) to the public water system. Some backflow preventers are manufactured to a very high standard and are more reliable in preventing backflow than devices manufactured to a lower standard. The more reliable assemblies must be used to prevent backflow in high hazard cross- connection situations. 9/24/2007 35 Types of Backflow Prevention Devices Atmospheric Type Vacuum Breaker Pressure Vacuum Breaker Double Check Valve Assembly Reduced Pressure Principle Assembly Reduced Pressure Principle Detector Assembly Double Check Detector Assembly 9/24/2007 36 6
Common Manufacturers of Mechanical Backflow Devices Watts Wilkins Conbraco Febco 9/24/2007 37 Atmospheric Vacuum Breaker Series 288A (1/4 3 ) Ideal for low flow, non- continuous flow installations Consists of a brass body construction (288A) or chrome finish (288AC), chemical resistant silicone seat disc, and an atmospheric vent to prevent spilling Prevent the reverse flow of polluted water from entering into the potable water supply due to backsiphonage 9/24/2007 38 Atmospheric Vacuum Breaker Atmospheric Vacuum Breaker 288A Static Vent No Flow Condition Static Flow Condition Dynamic 9/24/2007 39 9/24/2007 40 Installation Requirements Equipment Requiring Protection Atmospheric vacuum breaker 9/24/2007 41 9/24/2007 42 7
Potentially Submerged Inlet Pressure Vacuum Breaker 9/24/2007 43 9/24/2007 44 Hose Connection Vacuum Breakers (Bibb Vacuum Breaker) Series 8 ¾ Hose Bibb Ideal for inside and outside, health hazard installations requiring non-continuous pressure such as service sinks, swimming pools, laundry tubs, wash racks, dairy barns. Consists of a brass body construction, stainless steel working parts, and a rubber diaphragm and disc Permit the attachment of portable hoses to hose thread faucets and prevent the reverse flow of polluted water into the potable water supply due to backsiphonage 9/24/2007 45 9/24/2007 46 Dual Check Valve Backflow Preventer Dual Check Valve Backflow Preventer Series 7 or 7C 3/8 Model 7 consists of brass body Model 7C consists of chrome-plated brass body Contains 2 independently operating check valves and stainless steel springs Designed for continuous pressure applications 9/24/2007 47 9/24/2007 48 8
Dual Check Valve Backflow Preventer Series H7, H7C (hose connection) 3/4 Chrome-plated brass body construction Contains 2 independently operating check valves, stainless steel springs, & pressure plates Hose Connection: H7 brass H7C chrome-plated Designed for continuous pressure applications Pressure Washer 9/24/2007 49 9/24/2007 50 Backflow Preventer With Intermediate Atmospheric Vents Series 9 ¼ ¾ 9D for smaller supply lines, such as processing tanks, dairy equipment, boiler feed lines Consists of a brass body with stainless steel internal parts, integral strainer, and two durable, tight-sealing, rubber check valves 9/24/2007 51 Backflow Preventer With Intermediate Atmospheric Vents Series 9 ¼ 3/8 9BD beverage machine water supply lines Stainless steel body construction, rubber parts, dual check valves, ball check valve, and an atmospheric vent Prevent the reverse flow of contaminates, such as carbon dioxide gas and carbonated water, from entering the potable water supply 9/24/2007 52 Backflow Preventer on Vending Machines Soda Carbonator 9/24/2007 53 9/24/2007 54 9
Dual Check Valve for Carbonated Beverage Machines Series SD-2 Ideal for use on post-mix carbonated beverage equipment and dispensing equipment for tea and coffee Consists of a stainless steel body construction with internal rubber components and is designed for continuous or intermittent pressure applications Prevents the reverse flow of contaminated water, such as carbon dioxide gas and carbonated water, from entering into the potable water supply due to backpressure backflow Equipment Requiring Protection 9/24/2007 55 9/24/2007 56 Warewashing Machines Warewashing Machine w/a Direct Waste Connection A warewashing machine may have a direct connection between its waste outlet and a floor drain when the machine is located within 5 feet of a trapped floor drain and the machine outlet is connected to the inlet side of a properly vented floor drain trap. 9/24/2007 57 9/24/2007 58 10