Understanding Cross-Connections
Any link, existing or possible, between the public drinking water supply and a source of contamination such as chemicals, bacteria, pesticides or wastewater counts as a cross-connection.
Typical cross-connections at a home include:
- A garden hose resting in water that is not safe to drink, such as a bucket of soapy water, a hot tub, a swimming pool or an animal trough
- A lawn sprinkler system
Typical cross-connections at a business include:
- Soda fountain carbonators
- Irrigation systems
- Chemical dispensing equipment
- Fire sprinkler lines
- Pressure washers
What Is Backflow?
Drinking water reaches your home through a network of city pipes known as the distribution system. Pressure is what moves the water. When you open a faucet, pressure at that point falls to zero, and water travels toward that low-pressure spot and out of the tap. This is also why your water pressure may dip when a city main breaks: water rushes toward the break, which is now the point of lowest pressure.
The city keeps the system pressurized in several ways, and elevated storage tanks are the most important. They hold enough pressure in the lines for water to flow whenever someone turns on a tap.
Because the whole system depends on pressure, a sudden break or pressure drop can make water run the wrong way.
Picture filling a backyard pool with a garden hose, with the end of the hose lying underwater.
Now suppose firefighters open a hydrant near your home to fight a fire nearby. Pressure falls sharply at the hydrant. Water in the area moves toward that larger drop (the hydrant, not your hose, because its pipes are so much bigger), and the flow in your hose reverses.
With its end submerged, the hose begins pulling pool water back into your plumbing and into the city's mains. That is a backflow event. By leaving the hose underwater, you linked the pool directly to the public water system (a cross-connection), and the pressure drop on the city's side caused pool water to drain into the drinking water supply.
How can this be prevented? Mostly through awareness. Many people simply do not know about the cross-connections that may exist at home or the trouble they can cause. The city regulates every commercial and industrial site to prevent cross-connections and backflow, but it can only reach homeowners through education, such as the information on this page.
Outdoor Water Hoses
A hose left in a pool while it fills is one of the most common cross-connections at a home. The easy fix: never let the hose's open end sit below the water line.
Hose-end sprayers used for fertilizers or pesticides can also create a cross-connection. Only some models come with backflow protection already built in. A hose left lying in a puddle poses the same kind of risk.
The best protection for outdoor hoses is a hose bibb vacuum breaker on every outside faucet. This small, inexpensive device screws onto the faucet and shuts off flow when it senses water moving backward from the hose. Most hardware stores carry them.
Irrigation Systems
Sprinkler systems can also create cross-connections. Pop-up sprinkler heads sit below ground when they are not running, and dirty water can pool around them. If pressure drops, that water can be drawn back into the public system through the heads. For this reason, the city requires a backflow preventer on the water line of every new in-ground irrigation system.
A backflow preventer uses check valves that close when the device senses a pressure drop on the supply side or water flowing in reverse.
New in-ground sprinkler systems must use a device called a double check valve, which has two of these check valves to keep water from flowing back into the distribution system.
Kitchen Vegetable Sprayer
Cross-connections can exist indoors, too. Most sink and tub faucets sit at least an inch above the rim. That space, called an air gap, makes a cross-connection impossible, because the faucet can never end up below the water line. The kitchen vegetable sprayer is the exception, since it is really a hose attached to the faucet.
If the sprayer is left lying in a sink that fills with water, its head can end up submerged. A pressure drop in the city main could then pull that dirty water backward through the sprayer and into the distribution system. The answer is simply to pay attention when you use the sprayer and keep it out of standing water.
Toilet
A toilet can also be a source of cross-connection. Many older toilets, and some still sold today, have a fill valve that sits below the water level in the tank. When you repair a toilet, choose a flush mechanism with the fill valve mounted above the tank's water line. A classic case: a resident calls the city because blue water is coming out of the faucets. The cause turns out to be a tank cleaner that dyes the water blue, combined with a submerged fill valve. When pressure drops enough outside the home, or even in another part of the house, water from the toilet tank flows back into the household plumbing and out of the taps.
The city is committed to keeping your drinking water clean and safe. You can help by preventing cross-connections at home.
Backflow Tester Registration
Every backflow tester who works in the City of Fredville must complete an annual registration with the city's Health and Environment Department. Send the registration form and supporting documents by fax to (555) 010-2536 or by email to [email protected]. To pay fees, call (555) 010-1261, or stop by the department's second-floor office at City Hall, 100 Civic Center Drive, 2nd Floor, Fredville, TX 75999.
What to Submit
- Backflow tester registration form (PDF)
- A state-issued backflow prevention assembly tester license for cross-connection work
- Any related licenses you hold, including your driver's license and a fireline tester license if it applies
- A current calibration report for your test gauge
- The $90 registration fee
- Approved test booklets, $20 each; testers must use them
Backflow Program Fees
| Service | Fee |
|---|---|
| Tester registration | $90.00 |
| Tester inspection booklet (tax included) | $20.00 |
| Installation inspection | $90.00 |
| Re-inspection of a failed device | $45.00 |
| Annual fee, per device | $30.00 |
Licensed Backflow Testers
A list of the licensed backflow testers registered with the City of Fredville is available (PDF).
Who Needs a Backflow Assembly?
Backflow prevention assemblies are required at all commercial and industrial properties, on irrigation meters and at most multifamily properties. Single-family homes with irrigation systems must have them as well.
Installation and Initial Testing
The Health and Environment Department conducts the first test on every new commercial domestic backflow assembly, for a fee of $90.
Installing any new backflow assembly also requires a $55 plumbing permit, issued by Building Inspections. Installation or replacement must be done by a licensed plumber or licensed irrigator.
Testers must be able to reach every installed assembly. Above-ground assemblies may be mounted no higher than five feet unless a permanent platform is built. Reduced pressure zone assemblies (RPZA) installed above ground outdoors must be enclosed in an insulated hotbox to protect them from freezing.
The city's cross-connection ordinance (PDF) sets out the full installation specifications. Standard drawings are also available:
- Double check assembly detail (PDF)
- Fireline double check detail (PDF)
Call (555) 010-1261 to set up a test or to ask about backflow prevention devices.
Backflow Assembly Test Reports
Testers submit their reports through the city's online backflow test-report portal. A step-by-step guide to entering results in the online backflow test-report system is available (PDF).
Fireline Requirements
- A double check detector assembly (DCDA) is required on every new fireline.
- Fireline assemblies may be tested only by a state-certified tester who is registered with the city and works full time for a licensed fireline contractor.
At a glance
- Fee
- $90 registration; test booklets $20 each
- Who needs it
- Testers who certify backflow devices in Fredville, and property owners whose devices need yearly tests
- How to apply
- This one is not in the online permit portal; use the application below.
- Application
- Sample application for this permit
- Turnaround
- About 14 business days
- Questions
- (555) 010-1261, [email protected]
Fredville is a demonstration city built by Talk to Fred. Names, numbers and details on this page are sample content.