# Water Quality of U.S. Drinking Water Kiosks: Lead Release from “Lead-free” Plumbing after Reverse Osmosis Treatment

## TL;DR

This study finds that water from kiosks, despite treatment, often has higher lead levels than tap water due to plumbing corrosion.

## Contribution

The paper reveals that RO-treated kiosk water can leach lead from 'lead-free' plumbing, a previously under-recognized public health risk.

## Key findings

- Reverse osmosis treatment can lead to corrosive water that leaches lead from plumbing.
- Lead levels in kiosk water frequently exceeded health and regulatory standards.
- XRF analysis confirmed lead release from plumbing components labeled as 'lead-free'.

## Abstract

Many Americans distrust tap water, leading them to purchase
more
expensive drinking water sold from water vending machines (e.g., kiosks)
that are poorly regulated and sparingly monitored for quality. Here,
we analyzed the water quality of 20 kiosks from 4 different manufacturers
across 6 states in the first comprehensive comparison of the chemical
and microbial characteristics of kiosk water to paired tap samples.
Of the 16 kiosks listing specific water treatment processes (others
indicated “filtered” or “purified”), only
1 dispensed water with ionic composition (e.g., Na+, Ca2+, Mg2+) inconsistent with the stated treatment.
Most kiosks tested used reverse osmosis (RO), which removed fluoride
and residual disinfectant, although we found no evidence of microbial
contamination. RO also provided the benefit of removing per- and polyfluoroalkyl
substances. However, we frequently detected higher lead levels in
kiosk water than in nearby tap water. Lead was detected (>0.05
μg/L,
our method detection limit) in 15 kiosks; 5 were >1 μg/L
(American
Academy of Pediatrics recommendation), 2 were >5 μg/L (FDA
allowable
level for bottled water), and 1 was >10 μg/L (US EPA Action
Level). Lead co-occurred with zinc and copper, consistent with corrosion
of lead-containing plumbing materials. XRF analysis of plumbing in
2 kiosks from different manufacturers with nationwide distribution
confirmed this suspicion although all components in question met the
definition of lead free under the Safe Drinking Water Act. Lead release
was most evident with the use of RO treatment, which can produce
corrosive water low in alkalinity and pH. Going forward, the removal
of lead-containing plumbing components downstream of RO treatment
and regulation with routine testing of kiosk water quality is imperative
to address this unchecked public health risk.