Diverticulitis could certainly be complicated by an over-abundance of E Coli, but it sounds unlikely that diverticulitis alone (lacking E Coli complication) would explain what Kendall described.

As I expected, it sounds to me like Jacqui has it all well in hand.

In our community, when E Coli in wells gets out of hand (some is usually safely present), we just dump bleach in it to knock it down. (The carrying capacity vs. sparse population here is such that bleach does not affect the total groundwater supply, and what we send downstream is fine.) In a more densely populated or more rapidly-vertical runoff topography, that would neither do the trick nor be safe for downstreamers.

The other factor they will be looking at is probably whether the E Coli found in the labwork is the same safe type most well water contains.

~S~