Holding(s) in Company

1. Identity of the issuer or the underlying issuer of existing shares to which voting rights are attached (ii):

HYDRO INTERNATIONAL PLC

2. Reason for the notification (please state Yes/No): 

An acquisition or disposal of voting rights: (YES)

An acquisition or disposal of financial instruments which may result in the acquisition of shares already issued to which voting rights are attached: ( )

An event changing the breakdown of voting rights: ( )

Other (please specify) : ( )

3. Full name of person(s) subject to the notification obligation (iii):

Impax Environmental Markets PLC

4. Full name of shareholder(s) (if different from 3.) (iv):

Nortrust Nominees Limited 

5. Date of the transaction (and date on which the threshold is crossed or reached if different) (v):

22 May 2009 

6. Date on which issuer notified:

26 May 2009 

7. Threshold(s) that is/are crossed or reached:

6%

8. Notified details:

A: Voting rights attached to shares

Class/type of shares if possible using the ISIN CODE

Situation previous to the Triggering transaction (vi)

Number of shares

Number of voting Rights (viii)

Ordinary Shares

GB0004499488

835,000

5.92%

Resulting situation after the triggering transaction (vii)

Class/type of shares if possible  using the ISIN CODE

Number of shares 

Number of voting rights (ix)

% of voting rights

Direct

Direct (x)

Indirect (xi)

Direct

Indirect

Ordinary Shares

GB0004499488

892,900

892,900

Nil

6.27%

Nil

B: Financial Instruments

Resulting situation after the triggering transaction (xii)

Type of financial instrument

Expiration Date (xiii)

Exercise/Conversion Period/ Date (xiv)

Number of voting rights that may be acquired if the instrument is exercised/ converted.

% of voting rights

N/A

Total (A+B)

Number of voting rights

% of voting rights

892,900

6.27%

9. Chain of controlled undertakings through which the voting rights and/or the financial instruments are effectively held, if applicable (xv):

N/A

Proxy Voting:

10. Name of the proxy holder:

N/A

11. Number of voting rights proxy holder will cease to hold:

N/A

12. Date on which proxy holder will cease to hold voting rights:

N/A

13. Additional information:

N/A

14. Contact name:

Tony Hollox

15. Contact telephone number:

01275 878371