A new UK challenge is offering funding to councils, environmental organisations and other bodies to investigate whether self-contained sanitation technologies could provide an alternative to septic tanks while reducing nutrient pollution and water consumption.
The Flush Forward Challenge, launched by Challenge Works with funding from the Gates Foundation, will select up to three UK organisations to investigate applications for so-called Reinvented Toilet technologies and other novel non-sewered sanitation systems.
Each successful organisation will receive £40,000 to fund six months of staff time, alongside technical support, training and analysis. The programme is intended to identify locations where decentralised treatment could address problems associated with properties that are not connected to mains sewerage.
Challenge Works estimates that around one million UK homes rely instead on septic tanks, cesspits or small sewage treatment plants. It says that, with septic tanks typically lasting between 20 and 40 years, an estimated 25,000–50,000 systems could require replacement each year.
The challenge will examine whether newer non-sewered technologies could provide an alternative. These can range from compact treatment systems incorporated into an individual toilet to larger units capable of replacing a septic tank.
Reinvented Toilet systems are designed to treat human waste locally without requiring a connection to a sewer and, depending on the technology, without mains water or electricity. Potential functions include pathogen removal, water recovery and the recovery of resources such as nitrogen, phosphorus or biochar.
The broader category of non-sewered sanitation systems is covered by the ISO 30500:2025 international standard, which sets safety and performance requirements for prefabricated integrated treatment units. The standard covers systems that collect and fully treat waste without connection to networked sewerage, and includes considerations such as nutrient recovery, water consumption and reuse, and energy consumption and recovery.1
Challenge Works suggests the technologies could have particular relevance in areas with large numbers of septic tanks and problems with nitrogen or phosphorus pollution. Septic tanks provide primary treatment, with further treatment generally taking place in the surrounding ground, creating the potential for nutrients and pathogens to enter the environment where systems are unsuitable or poorly managed.
The programme will seek applications from organisations dealing directly with the effects of non-sewered sanitation, including councils, river trusts, environmental groups, national parks and small water companies.
Successful participants will analyse sanitation problems within their regions, convene relevant stakeholders and identify potential interventions, including Reinvented Toilet and other ISO 30500-compliant technologies. The programme will culminate in proposals setting out where such systems might provide environmental and other benefits.
Challenge Works also identifies constrained sewer capacity and nutrient neutrality requirements as possible areas where decentralised sanitation could eventually have a role, including in locations where wastewater infrastructure presents an obstacle to new housing. The current programme, however, is intended to investigate potential applications rather than fund installations.
Catherine Duncan, senior programme manager at Challenge Works, said: “Organisations working in areas affected by non-sewered sanitation understand the pressures facing their environments and communities better than anyone.
“Through the Flush Forward Challenge, we want to give these problem owners the funding, evidence and practical support they need to explore whether a new generation of non-sewered sanitation technologies could offer a better way forward.
“Reinvented Toilet technologies have the potential to treat waste safely without relying on water, sewer or mains power connections. By working with organisations that manage issues first-hand, we can build a clearer picture of where the technologies could make a meaningful difference in the UK.”
Challenge Works also sees the UK as a potential proving ground for technologies originally intended to address inadequate sanitation internationally. It argues that demonstrating systems in a mature, regulated market could help establish demand and lower production costs, potentially supporting wider deployment in lower-income countries.
Entries for the Flush Forward Challenge opened on 5 October and close at noon on 16 December 2026. To enter or find out more, visit flushforward.challenges.org.
Notes
[1] International Organization for Standardization, ISO 30500:2025 — Non-sewered sanitation systems — Prefabricated integrated treatment units — General safety and performance requirements for design and testing.
