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The vortex flush solution reducing water demand by over 90%

  • The vortex flush solution reducing water demand by over 90%

About the entity

Isle Utilities
Innovation consultancy specialising in the development and commercialisation of emerging technologies in the water & environmental sectors.

It’s astonishing that 2.6 billion people worldwide still do not have access to hygienic sanitation due to water scarcity and lack of resources. This results in an increased risk of waterborne diseases, in fact for so many around the world the simple action of a toilet flush is still a distant fantasy.

The first flush toilet, designed in 1592, flushed with 26 litres of water. Most modern toilets typically flush on 6 - 9 litres of water, however, some flush on 12 litres or even 20 litres, displaying some improvement in water demand for basic hygiene compared to the original design. However, these progressions are far from the finish line especially for those living in deprived areas or in homes with little to no water piping systems.

Arumloo, a South African retailer, invented and supplies nature-based water efficient design sanitaryware. Based in KwaZulu-Natal, the founder Jonny Harris saw a need for further reconstruction of the modern-day toilet with the belief that everyone has the right to reliable, dignified sanitation. Arumloo created a modern toilet that will clear waste reliably on just 2 litres of water, providing sanitation opportunities to all, whilst reducing water demand.

Arumloo recently participated in a trial of two types of their product, with the support of the Trial Reservoir.

The Arumloo trial

The purpose of the trial was to demonstrate the performance and acceptance of the ArumlooTM low flush toilets in a busy school in Botswana. The poor condition of school sanitation facilities often has a negative impact on the learning environment, plus toilet flushing represents a large portion of the school’s water bill. An effective, durable, ultra-low flush toilet presents the opportunity to massively reduce the water demand.

One hundred and eighty toilets were supplied to NextGen Waterfree Solution for installation of ceramic Arumloos for the staff, and the more robust plastic models for the pupils. The initial trial installed 120 at Botlhale Cambridge International School, in Gaborone. NextGen offered to implement the water saving installations at zero capital cost to the school, in return, the school agrees to pay the water cost saving for a period of two years of up to 50% water saved on campus to NextGen (all savings over 50% will be for the school’s benefit). 

The water saving installations included the replacement of all existing toilets with the ArumlooTM ultra-low flush toilet, and in addition water efficient taps were fitted to all handbasins. To accurately measure the results of the trial, a sample of toilets were fitted with smart meters to log both the flow and the number of flushes, enabling leakage monitoring and verification of the two-litre flush claim.

How does the ArumlooTM work?

The Arumloo toilet takes inspiration from the Arum Lily, whose elegant shape incorporates a vortex to bring insects into the heart of the flower for pollination. Arumloo encompasses this design in their product: the vortex shape of the toilet will effortlessly clear waste from the bowl without wasting water.

This design also reduces the amount of air that gets trapped under the toilet paper, removing the need for multiple flushes with even the largest solids. Conventional, modern toilets often suffer solids getting stuck in the tight U bend. Arumloo were able to understand how the water moves naturally and have improved the design of the P-trap, creating more space where it’s needed whilst eliminating the need for more water to transport solids to the sewer.

Results of the trial

Prior to the trial, the school’s water demand was as high as 400 kl/month with a water bill of more than P200,000 (≈US$14,870 or ≈£11,720) per month.

After the installation the monthly water demand dropped below 200 kl/month. By using the correct flow data, Arumloo estimated that the productive demand reduced from 21 kl/day to 6 kl/day after the installations.

The NextGen installation reduced the overall water demand by 93.2%, and if we exclude the reduction in leakage achieved by replaced old, leaking sanitaryware, the toilets produced a 71% water saving, which is significantly exceeds the trial’s target of 50% savings. Moreover, analysis of the sub metering within the toilets confirmed that there was no recorded leakage. The financial benefits to the school are obvious, however, there is a positive climate impact which is even more important.

The Arumloos are saving the school 1171 kL water per year. The energy demand to produce potable water in Botswana is 0.5 kWh/kl[1], which means the water saving provides a 585.5 kWh energy saving. Since 93% of the power supply in Botswana is derived from non-renewable sources (mainly coal and oil)[2], the greenhouse gas emitted is 0.8 kg CO₂/kWh, providing a total annual carbon saving of 468 kg CO₂/year at the trial site alone.

Next Steps

The trial was an astonishing success, exceeding expectations of water demand reduction and leakage prevention. The demonstration of the Arumloo has also attracted visits from other schools and the Ministry of Education which has led to the appointment of NextGen for additional Arumloo installations at other schools and public buildings.

“The Trial Reservoir provided us with the opportunity to fast track the demonstration of our water saving toilet to a new market in Botswana. The support from the Trial Reservoir Team was fantastic, and the media coverage that followed the successful trial has opened doors to other new markets. Thank you!” (Arumloo)

[1] Our World in Data, 2022. https://ourworldindata.org/grapher/carbon-intensity-electricity

[2] International Renewable Energy Agency, 2022. https://www.irena.org/-/media/Files/IRENA/Agency/Statistics/Statistical_...

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