The water company began the process of metering 500,000 households, which is schedule for completion in 2015, in late 2010 and has so far fitted about 200,000 in Hampshire, Sussex and Kent.
For metered customers, there are a range of tariffs available and those applying for the support tariff received a water and energy use audit.
The auditors, from the charity Groundwork, then referred the customers to a social enterprise who have helped them claim and benefits or tax credits they are eligible for but are not receiving.
So far, about 400 customers have benefitted by an average of £1,700.