When anaerobic water is drawn back over through the aerobic zone for oxidation and use, half of the oxidized iron will remove oxidizable material without redissolving, allowing the water to be cleaned. As half of the insoluble ferric iron (Fe2O3) gets reduced to ferrous oxide (FeO), it remains insolubly attached to remaining (Fe2O3) as the still insoluble black magnetic iron oxide (Fe3O4). It is only upon further bioreductions that iron will truly redissolve. This explains how the withdrawn water actually ends up getting usefully purified (up to a limited quantity).

Generally, microorganism activity is involved in the aspect of keeping aquifer zones relatively unplugged from iron build-up; but it seemed a bit more complicated to describe this briefly enough. When oxygen invades the aquifer, aerobic bacteria help oxidize the iron for energy and any iron that precipitates may absorb up to 50% of any trace levels of soluble organic TOC that may have been present. But, when well withdrawals commence, reverse flow of water pulls anaerobic conditions back over the previously precipitated iron within the aquifer. In absence of oxygen overlying the iron silts, dormant anaerobic bacteria come back to life to use the oxidized iron to metabolize the captured organics concentrated on said iron. This resolubilizes the iron, allowing it to drift away before a return of diffusing oxygen occurs by the next cycle. Explaining the ubiquitous and natural occurrence of beneficial and non-hazardous "bacteria" being stimulated in the well seemed to be a whole extra topic to explain.

Introduction of oxygen to ground water sources tends to protect the ferrous alloys of such casings from accelerated corrosion. As with standard water mains carrying air-entrained water supplies or aerobic well waters, iron develops a stable oxide in contact with such water conditions. Aeration also reduces the development of anaerobic conditions of sulphide formation which can indeed attack iron surfaces to demetallize them. Secondly, for the more acidic well supplies, a modest stripping removal of acidic carbon dioxide may slow any acidic attack on metal surfaces by a limited pH increase - but not enough to cause lime-based scaling. The recycling aeration of the water all the way down to the aquifer interface causes air diffusion right into the local aquifer zone (effected during pump idle downtime) to develop a limited zone of aerated filter operation upon water withdrawal. This tends to filter out most of the oxidation-susceptible iron and manganese so as to inhibit excess of these minerals from even entering the well itself. Effects on water treatment would be the same as needed for a standard aerobic well source. In most cases, little or no changes would be required upon an actually improved water quality as with aerobic sources.