Should you flush the tap before making baby formula in an old house?
Yes. Run cold tap for 30 to 60 seconds before any water touches the bottle, especially first thing in the morning.
What's actually in it
Older homes have lead pipes or lead solder somewhere in the plumbing. Water that sits in those pipes overnight pulls more lead. Whether your tap actually leaks lead also depends on the water chemistry. Soft, slightly acidic water dissolves more lead. Hard, alkaline water coats the pipes and holds the lead in place.
What the research says
A 2026 study in Geohealth mapped US groundwater chemistry against kids' blood lead by county. Counties with soft, acidic groundwater had higher children's blood lead even after housing age and income were controlled. Lead in water sitting overnight in pipes is the worst.
For formula in an older home, run cold tap for 30 to 60 seconds before catching the water. Never use the hot tap for formula or food. Get a NSF/ANSI 53 lead-rated filter on the kitchen tap. Use that filter for all baby and toddler drinking water. The EWG Tap Water Database shows your local water chemistry by zip.
The research at a glance
| Study | Journal | Year |
|---|---|---|
| Groundwater Chemistry and Children's Blood Lead Levels: A County-Wise Analysis in the United States | Geohealth | 2026 |
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