Symptoms
- Water tastes or smells different after using a garden hose or sprayer
- Discoloration coinciding with irrigation or pool use
- No backflow preventer visible on outdoor hose connections
- A plumbing inspector or water utility flagged a potential cross-connection
Likely causes
- CommonGarden hose submerged in a pool, tub, or chemical sprayer without a backflow preventerUnder certain pressure drops, contaminated water can be siphoned backward into the clean water supply.
- CommonMissing or failed backflow preventer on an irrigation systemIrrigation systems are required in most areas to have a working backflow device, which can fail over time.
- PossibleBoiler or heating system cross-connected without proper isolationSome heating systems can create a cross-connection risk if not properly isolated from the potable water supply.
- Less commonMunicipal water main issue causing a pressure drop and siphoningA sudden drop in city water pressure (like from firefighting nearby) can pull contaminants backward through any unprotected connection.
What to do
- Immediately disconnect any hose that was submerged in a pool, tub, chemical sprayer, or other non-potable water source.
- Always use a hose bib vacuum breaker (a simple inexpensive device) on outdoor spigots used with hoses, especially for chemical sprayers.
- Check your irrigation system's backflow preventer for visible damage, and note whether it has been tested recently, since many jurisdictions require annual testing.
- If you notice unusual taste, smell, or color in your water following any of these situations, avoid drinking it and run other fixtures to flush the lines.
- Contact your water utility to report a suspected cross-connection event, since they can advise on immediate safety and may test the water.
- Have a licensed plumber inspect and, if needed, install or repair backflow prevention devices at vulnerable connection points.
- Going forward, never leave a hose connected without a vacuum breaker, and never submerge a hose end in any non-potable liquid.
Tools and parts
- Hose bib vacuum breaker (preventive)
Hose bib vacuum breaker or backflow preventerSearch: “hose bib vacuum breaker backflow preventer”
When to call a pro
Call a licensed plumber to inspect and repair backflow prevention devices, and notify your water utility of any suspected cross-connection event.
Safety
Use caution
If you suspect contaminated water has entered your supply, avoid drinking or cooking with tap water until it's been flushed and confirmed safe; contact your water utility for guidance.