Aid groups and development banks have come up with the perfect, albeit ironic, solution for investors that have seen billions of dollars go down the pan during the financial crisis. Invest in toilets.

The groups are trying an alternative way to try and address dire sanitation problems in developing countries, shunning the traditional route where governments fund and build toilets, and instead marketing toilets as must-have status symbols, creating demand among poorer populations.

It's a bit like the mobile phone. Jon Lane, Executive Director of the U.N.'s Water Supply and Sanitation Collaborative Council (WSSCC).

Before, nobody had a mobile phone but now everyone wants one and people who were selling fruit and veg are now selling Nokias and sim cards. That's what needs to happen with toilets.

The U.N. currently estimates that around 2.6 billion people or 40 percent of the world's population do not have access to basic sanitation, with diarrhoea killing 1.8 million a year.

The toilets Lane is talking about are simple pits, 2 metres (yards) deep and about 1 metre wide with a squat plate over the top. They cost around $100 to buy and build, and with an occasional sprinkling of soil or ash a typical family would not have to empty it for 2-3 years.

The WSSCC and banks with development arms, like Germany's KfW, want to change the way money is spent on such projects. Instead of paying people to do the work, they want to provide the cash to banks in the local countries who then give loans to those looking to create a business providing toilets.

The thing is that if local authorities go in and build a toilet in someone's back yard, it has been shown that half of them are not even used, said Lane.

People feel they weren't asked about it, and they are not told how to use it so they don't use it. But if it's personally motivated then it tends to be different.

The hope is to create a new source to tap for investors and that financing from banks like KfW and the European Investment Bank will feed a $40 billion investment in santitation.

KfW and the EIB would then sell their development project-based bonds to institutions and others keen to invest in the top-rated and ethically pleasing instruments.

The WSSCC's Global Sanitation Fund plans to bolster the private money with $100 million a year on marketing in countries ranging from India to Uganda, to drum up a must-have feel around toilets, and create the platform for entrepreneurs.