Water.   Unit 7,  Water supply and sewage treatment / 
Prepared by the Course Team. 
 - Milton Keynes :  The Open University,  1995. 
 - 2nd ed. 101 p. :  ill.(some col.) ;  30 cm. 
 - Environmental control and public health. .
<br/><br/> Technology : a second level course. 
<br/><br/>Includes bibliographical references. 
<br/><br/><label>ISBN: </label>0749272988 (pbk.)