I must congratulate David de Hoxar in inventing a spiral separator (Business, July 10) and hope it realises the potential he obviously thinks it has.

Having said that, I can recall in the dim and distant past the screens that were installed at the Portobello in Telscombe Cliffs which the designers hoped would have the same effect. These, regretfully, failed after a very short of time. Southern Water was then obliged to open the sluice gates and once again pour untreated sewage into the channel.

The public would be more confident if Southern Water moved these experimental ideas away from the coast where they would not have the facility to pollute the beach if the system failed.

-Doug Lawrence, East Saltdean