I'm an emeritus professor of civil engineering at the University of Leeds in England. I've been working on low-cost sanitation in developing countries since the mid-1970s, and also on low-cost wastewater treatment and reuse. I was a lecturer at the University of Nairobi, Kenya, 1970-73 and then a senior lecturer at the University of Dundee, Scotland, 1974-79 before moving to Leeds in late 1979. I was a visiting professor of sanitary engineering at the Universidade Federal da Paraiba in Campina Grande, northeast Brazil, during 1976-95, and since 1996 I have been a visiting professor of environmental engineering at the Instituto Cinara, Universidad del Valle in Cali, Colombia.