Danny Wills, via Skype, said a simple lock on a community toilet made a huge difference

Danny Wills: As the government delivers what they define as solutions it's actually creating a lot more problems than they've understood from the beginning. Often half the time these systems will break and cause flooding, creating more problems downstream to natural ecosystems. We're looking at trying to come up with more innovative solutions that work with the delivery and handling of the waste of these systems.

RC: I don't think the design of the product is the real challenge here. If we go back to the mobile phone analogy, people in the developing world are not buying phones because they're nice objects, they're driven by a need to trade or social pressure.

There are programmes that have worked very well which generate guilt and shame in communities where people are still defecating outdoors and create a social pressure within a community to dig a toilet on your own property. That can be much more successful in accelerating toilet provision than an NGO or the local government coming along and saying you've got to do it. This isn't a technical problem, it's a cultural and social problem.

Robin Cross looked to promote pragmatic solutions, winning small battles

JC: The need for people in developing countries is the same need that we have here in developed countries. It's already aspirational, when you ask them what they would like to have, it's a toilet, it's not a strange seat, it's not a strange thing, it's the same toilet or squat pan that they're using in the cities.

PC: Where we work in rural Uganda, the reason people need toilets is when there is a higher density of population, such as at a school. To start with, one is creating that step between open defecation and the pit latrine. These are little steps towards the provision of sanitation. I think it's interesting that on this peri-urban edge where there are vast areas of Africa where there is no access at all to underground sanitation or even piped water, but there is a kind of aspiration that we're living in a dense enough environment that we have to do something about this and we have to have an immediate technology that suits that situation.

PS: What if we come up with a solution, which does the same thing the conventional system does, but doesn't need connection to pipes. The point is we don't have to restrict our thinking to only the current solutions.

JT: I was wondering if one of the options was this massive natural resource, which is being wasted. Can we commoditise that somehow?

PS: There is another way to see it as a natural resource of some sort, it's whether you have technology to capture those potentials.

PC: 45 years ago, there was this magical thing called the Clivus Multrum, it was supposed to be the answer to this: a dry toilet that would produce useful compost. Nothing seems to have happened since then.

Barbara Penner pointed out how important the issue of gender is in sanitation provision

DW: There are small companies that are developed out of communities that actually take the handling of sewage for ideas such as composting and even irrigation for agriculture. In Peru there's a company that has developed toilets that are not connected to any infrastructure but there are individuals that are paid on a monthly fee to come around and collect the shit. That is then turned into compost and sold to farmers for a profit. I think there are plenty of opportunities for these things to happen.

BP: There's a project in Madagascar building communal toilets not connected to any infrastructure. They are using the human faecal matter and composting it. But they're also producing biogas and they're allowing users to recharge their mobiles at the same time as visiting the toilet. I think that's just a really intelligent, inventive way of beginning to join up these issues.

JC: There is another project that has been funded by the Bill Gates Foundation as well, from the University of the West of England (UWE) - they're trying to obtain electricity out of urinals and they've installed one in a music festival.

CG: You have to win small battles here and there before we get in 50 years the perfect toilet system, where we don't need the sewerage and everything. There are a lot of ways of fixing the problem, it's not 'lets do nothing until we have the perfect toilet'.

RC: For me, it's about creating the cultural or political will to make the change happen. What about the number of women and children who are sexually abused because open defecation is still ok, it needs to be made not culturally acceptable because it damages peoples lives on too big a scale. Those are the sorts of issues that could become drivers for change in a way that a fantastic piece of technology alone will never do. It could simply be about more education and awareness. Diseases spread through poor sanitation cause something like 37% of childhood deaths under the age of five, but people just don't know that. Some of it is about spreading that knowledge.

PS: Since 1971, international development has been allergic to technological development because they're scared of technology. Take the example of the pharmaceutical industry. They're inventing vaccines and saving lives so why is it that we can't invent toilets and save lives. Why can't we be open to technological innovation in sanitation?

PC: There's no point in you going to buy a toilet system if there's no infrastructure to put it in. We need to start thinking about the situation on an infrastructural level.

PS: If you do think that we need infrastructure as the solution, then that means you need quite a huge upfront investment and it will become unfeasible because you will need some capital to dig our current system.

BP: We all know it's not enough to just provide a toilet, you have to actually convince people to use it and to do that you need to convince people to value something. I certainly think it is more productive to think about the problem in terms of this question about human rights, to see toilets not just as a technological solution but also as a dignified solution to various human problems.

I think the gender issue is the key one. Certainly at schools there is a lot of evidence now that many girls in sub-Saharan Africa aren't attending schools when they hit puberty because of the lack of toilet facilities.

The lack of something as basic as a toilet is a real obstacle to attainment and social improvement. It's a good example of how toilets are not simply straightforward pieces of technology.

You cannot talk about toilets without immediately finding yourself talking about so many other things as well: religious beliefs, attitudes toward sexuality, sex, gender and so on and it's very difficult to try to separate those issues.

Professor Sohail wanted to concentrate on a technological solution to sanitation issues

DW: At Urban-Think Tank we're trying to find the right way to upgrade and implement these ideas, for example, just by putting a lock on the communal toilet and having three families share it, other than it just being open, completely changes the scenario. We really understood that the users need to have responsibility and ownership of the solutions in order for them to be maintained and work. All of these solutions have to involve the community and that is a very time-consuming process, but we have to do these micro steps to chip away at the problem.

RC: I think this is the detail that we can do - we're a smart bunch of designers. We can solve the literage, the polymers, the issue is how we create the demand. Children are dying and massive numbers of work hours are lost, but sanitation isn't on the agenda. Those are reasons to have a toilet and where we need to intervene, and then the technology will follow.

We are Water Foundation statistics 2015

• 2,400 million people have no access to basic sanitation.
• Worldwide, there are almost as many people who have to openly defecate (946 million) as inhabitants of the African continent (1,100 million)
• There are more people in the world with a mobile phone than a toilet.
• 842,000 deaths a year could be avoided with adequate sanitation structures and hygiene.
• 1,000 children under 5 years of age die every day due to the lack of basic sanitation and drinking water.
• The lack of any toilet or latrine close to home is the reason why thousands of women experience sexual assault and rape every year.
• School dropout rates among adolescents would be lowered as much as 15% if they had access to sanitation services at school