I'd encourage people to look at Clean Thames and sign the petition against the supersewer. This is expensive, non sustainable [it'll probably fill with increased rainfall, concrete area and population, like a watery version of the M25] and will add £80 to Thames Water bills. 

Actually the £80 added to TW bottom line is probably why they're so keen on it, especially as it's being built with fairly cheap government money. There's some links to successful SUDS [sustainable urban drainage] projects on the website also.