customers. We keep each other
apprised of what’s happening in
the community and what’s happening in the water treatment plants.
How did MWW go about
researching a fix for
Cryptosporidium How did
you know where to look for
After the Crypto event, something
clearly had to change, and MWW
was not able to do that by itself.
With the help of consultants, we
investigated the best disinfection practices in the industry at
the time and the options for upgrading the various steps of
the treatment process. We relied upon WRF research to explore
our options. Ozone was chosen as the primary disinfectant
for the treatment process, and that was largely because of
work that had been done by the Water Research Foundation.
The Milwaukee Water Works became the first utility to
use ozone on a large scale as a primary disinfectant. The
improvements were put in place between 1995 and
1998. It was an initial investment of 89 million dollars to
do all of the upgrades and refurbish the two water treatment plants. Since then, MWW has spent an additional
460 million dollars maintaining our infrastructure.
Ozone—was that a surprise to anyone?
Ozone works because it is an incredibly powerful disinfectant.
Every organic molecule that it touches, it destroys. It was
chosen initially because it was known to kill Cryptosporidium,
but it turns out that ozone is actually a silver bullet for many
other substances in water. MWW found out later that ozone
also helps with coagulation and flocculation. We know that
it destroys many organic compounds like pharmaceuticals
and personal care products. It also destroys taste and odor
molecules, and even though it was put in initially as an anti-
Cryptosporidium weapon, I would put it in again tomorrow in
This year marks the Water Research Foundation’s 50th anni-
versary, and we are excited to celebrate 50 years of ground-
breaking water research. As part of this yearlong celebration,
WRF will be showcasing several subscriber utilities that have
achieved great things, in part because of their use of and
participation in WRF research projects. Recently, the Water
Research Foundation spoke with Carrie Lewis, Superintendent
of the Milwaukee Water Works, to discuss the utility’s decades-
long experience as a WRF subscriber. Milwaukee Water
Works, with the help of WRF research, became the first util-
ity to use ozone on a large scale as a primary disinfectant.
Water Research Foundation: What would you sa y is
the single greatest asset that the City of Milwaukee
has, in terms of providing clean water to its residents?
Carrie Lewis: Some people might say that Milwaukee’s single
greatest asset is Lake Michigan, because it is an abundant
and pristine source of water. I would say that Milwaukee’s
greatest asset for clean water is the Milwaukee Water Works
(MWW). Our utility takes that water and treats it to extremely
high quality standards to meet the needs of 865,000
people in Milwaukee and 15 neighboring communities.
Tell us about the Milwaukee Water Works. How would
you say MWW is an industry leader?
Milwaukee Water Works endured a Cryptosporidium event
back in 1993, but this event turned out to be significant for
every water utility in the country. All water utilities realized
that we are in the business of public health protection. I think
many utilities were complacent before that; we thought that
putting water in pipes and sending it out to people was really
all that we were doing. These days, we all know that utilities are really in the business of public health protection. No
water utility knows that better than Milwaukee Water Works.
One of the other things that Milwaukee Water Works is
known for is our relationship with our local health department.
We have a strong partnership with the Milwaukee Health
Department, and when there are substances of concern or
water quality issues, we work with them on messaging for our
Q&A with Carrie Lewis
Superintendent of Milwaukee Water Works
Milwaukee Water Works and Ozone