Summary for nails not rusting Discussion
The focus keyphrase, "nails not rusting," comes from a Kanchan arsenic filter troubleshooting question in Nepal: some filters had rusty nails working as expected, while others with the same nails stayed unrusted for about seven months despite repeated wetting and air exposure. Candice Young-Rojanschi noted that neighboring households using the same nail type but different wells did see rusting, suggesting the water source may be the key variable. In the discussion, the practical takeaway is that the well water chemistry likely differs enough to affect corrosion, rather than the filter design alone. The thread does not provide a single confirmed cause, but it points readers toward comparing the wells’ water composition and corrosion conditions to explain why some nails rust and others do not.
Q. Hello,
I was recently observing some Kanchan arsenic filters in Nepal (these are arsenic-removing water filters which rely on rusty nails as a source of ferric oxide). We came across a number of filters where the nails were not rusting. This is a mystery.
The nails have water poured over them, then are exposed to air, several times a day. The nails I observed had been in place for about 7 months, with multiple exposures to water and air every day over that time. We have tested the nails back home, and they rust quickly (as expected) under the same conditions using our tap water. Filters from neighbouring households using the same nails, but which drew water from different wells, were rusting fine.
What might be the cause of these nails not rusting in these homes?
Candice Young-Rojanschi
Researcher/ Troubleshooter – Calgary, AB, Canada
October 19, 2018