Backflow is not only a commercial concern. A garden hose left running into a bucket of weed killer, a hose dropped in a pool to top it off, or a laundry sink sprayer hanging in dirty water are all paths for backsiphonage if street pressure drops suddenly.
The sprinkler system usually gets the testable device, but the rest of the house matters too. Knowing where your home's cross-connections are lets you fix the easy ones yourself and ask the right questions about the rest.
Common home cross-connections
| Where | The risk | Usual protection |
|---|---|---|
| Outdoor hose faucets | Hose end in a bucket, pool, pond or spray applicator | Hose bibb vacuum breaker; keep hose ends out of liquids |
| Pool and spa fill | Fill hose or line submerged in pool water | Air gap, or an approved device on a fill line |
| Lawn sprinklers | Heads sitting in soil and puddles | Testable backflow device on the irrigation line |
| Water softener and filter drains | Drain hose pushed into a standpipe below the water line | Air gap at the drain |
| Hot water or hydronic boilers | Treatment chemicals and pressure in the loop | Backflow device on the fill line; ask a plumber |
| Laundry and utility sinks | Sprayer or hose left in standing water | Keep spouts above the rim; avoid submerged hoses |
Ten-minute walkaround
- Check that each outdoor faucet has a hose bibb vacuum breaker, or add one.
- Never leave a hose end submerged in a pool, bucket, tank or puddle.
- Remove hose-end chemical sprayers when you are done.
- Look at the softener or filter drain: there should be a visible gap above the drain.
- Find the backflow device on the sprinkler line and confirm it is not damaged.
- Note any fill line on a pool, pond or fountain and ask how it is protected.
When to call someone
- IfA hose bibb vacuum breaker leaks from its vent every time you use the faucetThenReplace the vacuum breaker; it is an easy homeowner fix.
- IfYou are adding a pool auto-fill, boiler or fountainThenAsk a licensed plumber what protection is required, and check with the city.
- IfYou suspect dirty water got into your house plumbingThenStop using the water for drinking and contact the water utility right away.
- IfYour sprinkler device is cracked or sprayingThenShut off the irrigation supply and book a tester.
Ask a plumber during other work
- Are there any unprotected cross-connections in my house?
- Is the softener or filter drain properly air-gapped?
- Does the boiler or pool fill line need a backflow device?
- Will any new fixture you are installing need protection?
Common questions
Do I need to test hose bibb vacuum breakers each year?
No. They are not testable assemblies. Check them for leaks and damage and replace as needed.
What does an air gap mean?
A physical open space between the end of a water outlet and the highest level the receiving water can reach. Water cannot jump the gap backward.
Could backflow make my water taste bad?
It is possible. If water suddenly looks, smells or tastes wrong, stop drinking it and contact the water utility.
General information for Fullerton, not a quote or professional advice. In an emergency, call 911.