Teachers Mutual Bank and Bank Australia are positioned to boost their respective shares of the deposits market after securing formal certification for the "sustainability" of their savings and term deposit products.The two customer-owned banks, along with Bendigo Bank, are the only local deposit-takers to have banking products approved by the Responsible Investment Association of Australasia (RIAA).The product accreditations mean that TMB and Bank Australia are in line to win new transaction banking mandates from environmental groups and other community organisations.It also opens the way for each bank to tap industry superannuation and ethical funds as new sources for deposits.While most industry funds offer "sustainable" or "socially responsible" investment options to their members, the mandates for managing the cash components of such portfolios are usually awarded to National Australia Bank or one of the other major banks.Only a handful of second-tier deposit-takers such as CUA and Members' Equity Bank currently source deposit funding through superannuation funds.TMB chief executive Steve James expects the RIAA accreditation to generate new deposits worth more than A$600,000 over the next 12 months and additional flows in subsequent years.The bank, which markets banking products under the Teachers Mutual, Unibank and Firefighters Mutual brands, has also secured certification for its mortgage products.James estimates that RIAA imprimatur will be contributing to the origination of around $1.5 billion of residential mortgages by 2021."This announcement demonstrates Teachers Mutual Bank Limited's determination to champion responsible investment," he said."We're acting on our values and aligning our business practices with our members' expectations."While RIAA is engaged with each of the major banks, none have so far been able to secure certification for any banking products.Certification requires a bank to make commitments in legal contracts with customers that they will meet benchmarks specified by the RIAA.RIAA chief executive Simon O'Connor said two leading domestic banks had submitted products for approval but he declined to name the organisations."We are talking to all of the major banks about the certification process," he said."I think it's fair to say that each see the value of having their banking products tested for sustainability and against socially responsible standards."While the RIAA provides certification on a product-by-product basis, O'Connor said that a bank's organisational culture and record as a responsible lender was also considered in the test process."We conduct organisational audits when a bank submits product to us for certification," he said."It will become hard to get a product certified if an organisation's culture and lending practices are not assessed as sustainable and responsible."O'Connor said that the association does not provide certification for a range of credit products because they were seen as problematic in terms of responsible lending."We do not certify credit card products," O'Connor said.More than 25 superannuation providers including Australian Super, CBUS and HESTA are affiliated with the RIAA, which means that banking products certified by the association will be brought to the attention of trustees of these funds.