NEW YORK, May 14 /PRNewswire/ -- Water Asset Management announced today
that it has issued the following open letter to stockholders of Insituform
Technologies, Inc. (Nasdaq: INSU):

    To Our Fellow Stockholders of Insituform Technologies, Inc.:

    At Insituform's Annual Meeting -- only three business days away --
stockholders will make a decision critical to the value of our investments
in the company.

    Over the past months, we have spoken with many of you. We appreciate
the substantial support and encouragement from our fellow investors -- many
of you long-suffering stockholders.

    Your message is unmistakable -- Insituform stockholders both large and
small are frustrated by the incumbent Board's disappointing track record of
failed acquisitions, missed opportunities and lack of strategic vision.

    Shareholders are demanding a change.

    The Incumbent Board Has Been Asleep at the Wheel

    Suddenly, in the midst of a proxy contest that threatens to replace
them, the incumbent board has awakened. They've announced a new business
plan and a new CEO. According to independent proxy advisory firm PROXY
Governance, Inc.:



    "what the board has offered shareholders in this election is little more
    than the promise that -- unlike the other strategic plans with [new CEO]
    Burgess' three predecessors -- this time the board has gotten it right,
    hired the right CEO, and is on the verge of delivering sustainable
    improvement in shareholder value." (May 12, 2008)
    Their Three Chief Weapons are Fear, Uncertainty and Doubt (FUD)

    Throughout this proxy contest, the incumbent directors have sought to
hide their own abysmal record behind absurd claims about Water Asset
Management and our Stockholder Nominees. They've said that we don't have a
business plan for the company and even that we threaten the future value of
your investment in Insituform.

    Not surprisingly, PROXY Governance, Inc. sees through management's FUD.
PROXY Governance understands our strategic plan for the company, and also
understands that stockholders have suffered mightily while the incumbent
board has been asleep at the wheel:



    "Structurally, there are few striking differences between the strategic
    plans proposed by the company and the dissidents. What is striking,
    however, is that it took a sudden 90% drop in profits, and the destruction
    of more than four years of share price appreciation, before the board
    identified the need for a strategic plan to mitigate business cycles by
    diversifying revenues, balancing geographic market exposure, developing a
    more adaptive cost structure, and implementing cross-sell and
    market-adjacency growth strategies. We recognize that the company's
    financial performance was generally improving through 2006, and that share
    prices - despite substantial swings -- increased by more than 40% over the
    four years prior to a disastrous 2007. Given the prominent role of
    "industry cycles" in the company's explanation of 2007 results, however,
    and the extensive strategic weaknesses which its turnaround plan has
    identified, we question -- as we believe any long-term shareholder would
    question -- whether those pre-2007 results were achieved due to, or
    despite, the guidance of the incumbent board." (May 12, 2008)
    The Incumbent Board's Record Speaks For Itself

    POOR STOCK PERFORMANCE: Insituform's shares have lost 13.2% of their
value over the past five years, while the Company's two handpicked indexes
for comparison have increased in value by 391.7% and 224.0%,
respectively.(1)

    POOR EXPENSE CONTROL: As recently as Q1 2008, gross margin remained
well below historical levels, and operating expenses were still greater
than analyst expectations, even after accounting for proxy related
expenses.

    INADEQUATE INTERNATIONAL SALES GROWTH: The incumbent Board references
operations in "40 markets," including North America (2 countries) and
Europe (perhaps 10 countries), which implies, based on the incumbent
Board's recent presentation, that sales in "rest of world" (approximately
28 countries) totaled a paltry $2 million in 2007.

    MISSED OPPORTUNITY TO GROW TITE LINER: Tite Liner sales have barely
grown in the last 3 years despite the unprecedented boom in mining and oil
and gas spending.

    Vote the BLUE Card Today to Ensure Change at Insituform

    Even the incumbent board seems to have awakened to the obvious need for
change. Yet the simple fact is that the board's platform -- yet another
business plan and yet another CEO -- only surfaced after we began our
public campaign to drive change at the company.

    In order to ensure that change comes to Insituform, stockholders need
new directors who have been committed from the outset to a program of
change, not the old crowd of directors that for so long has been asleep at
the wheel.

    Vote the BLUE Card Today via Telephone or Internet

    SPECIAL REMINDER: Given the company's "stockholder unfriendly"
scheduling of the meeting for 8 a.m. local time on Monday May 19th, you
should take immediate steps to have your proxy processed by Friday
afternoon May 16th in order to ensure your vote is received in time to be
counted at the meeting.

    Please feel free to call us directly, or call our proxy advisors,
MacKenzie Partners, Inc., at any time for further information at (800)
322-2885.



    Very truly yours,

    Matthew J. Diserio                   Disque D. Deane Jr.


    (1)  Represents total return for calendar years 2003 through 2007. The
         Company's handpicked indexes are identified in the Company's Form
         l0-K and in Water Asset Management's proxy statement, filed March 10,
         2008 and April 22, 2008, respectively, with the Securities and
         Exchange Commission.

    May 14, 2008


                         Biographies of Our Nominees

    * Nickolas W. Vande Steeg is a former President of Parker-Hannifin Corp.,
      having held a variety of executive and operating management positions
      over a 35 year career with that company.  Parker Hannifin is widely
      considered one of the best managed and most efficient companies in the
      S&P 500.  Mr. Vande Steeg has substantial experience in successfully
      implementing "lean" business practices in a large global enterprise and
      will provide significant leadership and insight to make the Company more
      efficient, flexible and competitive.

    * Senator Alfonse M. D'Amato offers a wealth of experience in governmental
      and international affairs on the federal, state and municipal levels.
      Municipal wastewater markets are the primary focus of the Company's US
      marketing efforts for rehabilitation projects, and we believe Senator
      D'Amato's experience, insight, and relationships will be invaluable.

    * Matthew J. Diserio and Disque D. Deane Jr. are President and Chief
      Investment Officer, respectively, of Water Asset Management, which
      invests exclusively in water-related companies globally.  In addition to
      vast experience in the water industry, Messrs. Deane and Diserio will
      bring to the Board significant financial experience.  We believe their
      financial and water industry experience and contacts will be an
      important addition to the new Board's expertise in the current financial
      environment, where creative approaches to financing municipal projects
      can provide a critical competitive advantage.

    * Richard Onses is a water industry consultant based in Barcelona, Spain
      and specializing in water utilities and water infrastructure projects.
      He formerly headed business development at Sociedad General de Aguas de
      Barcelona, SA, a large European water company, and has operated water
      and waste water assets on three continents. Given the growth of the
      Company's international operations, we believe that Mr. Onses'
      international experience and contacts in the water industry will be a
      valuable addition to the Board.

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