Two Bag Challenge: Using behavioural insights to reduce waste in Havering

The Two Bag Challenge asked households in two of Havering’s highest waste-producing areas to reduce their general waste to no more than two sacks per week. Delivery of the pilot, including communications, waste management guidance for residents, and waste-focused events in the local area, was informed by behavioural insights gathered from research with residents in the target areas, as well as wider behavioural science theory.

During the four-week challenge, the number of households presenting two bags or less per week increased by 39 per cent compared to the baseline. Average weekly waste tonnages (residual waste and recycling combined) decreased in one of the two target areas; from 16.72 tonnes during the baseline to 15.74 tonnes during the challenge. This reduction of 3.91 tonnes equates to a financial saving of £508, in just this one area of 1,287 households, over four weeks.

The challenge

Havering Council pays a similar cost per tonne of waste collected regardless of whether it is general waste or recycling. At the time of the challenge its total levy payable to the East London Waste Authority was around £16m per year. Being one of the most costly service areas for the council, waste collection and disposal is looked to as an area where expenditure can be reduced. Therefore, waste reduction initiatives and activities are encouraged and were in line with the council’s corporate plan priorities during the time of the trial. Havering Council has tried numerous waste prevention interventions and techniques in the past, but many of these activities can only target small numbers of residents at a time, and whilst impactful on individuals, Havering has not seen a demonstrable payback in waste disposal savings. This project therefore aimed to reduce total waste tonnages collected from households in high waste-producing areas, using a behavioural insight and resident-led approach to encourage waste minimisation behaviour within the community.

The solution

As households in Havering can currently present an unlimited number of general waste sacks for collection each week, it was decided that the intervention would test whether encouraging residents to stick to a maximum of two sacks per week leads to an overall reduction in the amount of waste generated. Two high waste-producing areas, representing different key demographic categories (identified using the population classification system MOSAIC) were selected for piloting (Heaton and Rainham & Wennington). In-depth qualitative research was carried out with eight residents in each area, exploring the behavioural context, drivers and challenges of household waste generation, and informing the pilot communications and engagement approaches.

Applying insight from the research, the Two Bag Challenge was developed. Households received a waste reduction pack containing a booklet with practical tips on how residents can reduce and effectively manage their waste, specific waste sacks to use for the duration of the challenge, a council letter to inform on the change in service, and tools to help reduce food waste (e.g. spaghetti measurers and bag clips). Resident meetings were held at the outset of the pilot and feedback communications were also distributed during and after the intervention to prompt engagement. This included a personalised ‘nudge’ postcard delivered to households still presenting more than two sacks halfway through the challenge, providing them with additional tips to increase engagement. These households were identified through weekly bag count monitoring of all households in the target areas, carried out by Havering Council waste officers. One of the two target rounds was also selected at random to be a high engagement area, receiving additional activity in the form of three waste-focused community events. The challenge took place over four weeks, identifying its impact through waste monitoring.

The impact (including cost savings/income generated if applicable)

The number of households presenting two bags or less per week increased by 39 per cent during the challenge compared to the baseline; this was a 52 per cent increase in Heaton, and a 29 per cent increase in Rainham & Wennington. While general waste reduced, recycling bag counts remained fairly consistent. We therefore assume waste was not shifted from general waste sacks to recycling, but was prevented entirely. Looking at waste tonnage data in Heaton, the average weekly tonnage reduced by 6 per cent from 16.72 tonnes during the baseline to 15.74 tonnes during the four weeks of the challenge. In Rainham & Wennington, the average weekly tonnage increased by 4 per cent from 13.22 during the baseline to 13.74 during the challenge month.

As the comparative control area for Rainham & Wennington also saw a 4 per cent increase in total waste tonnages for the same period, we suggest there were some external factors that led to an increase in waste and recycling at this time, which the Two Bag Challenge did not counteract in this area. This meant the individual efforts of some to minimise waste, as identified by the bag count data, did not lead to an overall reduction in tonnage.

As success for Havering Council lies in how far the pilot reduced waste tonnages, as this can lead to a tangible financial saving, we suggest the pilot was successful, achieving reduced waste tonnages in one of the two collection rounds targeted. This reduction in waste in Heaton equates to a financial saving of £508, over four weeks.

As this pilot was tested in high waste-producing areas only, we cannot apply these results to accurately identify exactly what impact the challenge would have if scaled across the borough, i.e. in lower waste-producing areas. However, using the data we have available, and assuming that lower waste-producing areas can still reduce waste to some extent (proportional to the smaller amounts they are currently producing), it is estimated that this could achieve a reduction in waste disposal expenditure of £262,218[1].

It is worth noting that this figure does not take into account the set up costs and potential on-costs if this was to be scaled up and become a long term initiative.  Set up costs could be between £203,500 - £215,000.  This does not include the provision of sacks.

If all areas performed like Heaton, where the intervention was particularly successful, the initial saving could be up to £3.67 per household, and if applied across the whole borough could equate to £388,848. This level of reduction is likely to be most possible in areas of similar socio-demographics and levels of waste production to Heaton, and where the pilot is repeated like-for-like. However, these savings could only be achieved if residents were to continue to purchase their own waste sacks as they do currently. As it stands, the impact of provision of sacks on the results of the trial is unknown.

When taking into account the whole of Havering, it is most likely the intervention will produce a tonnage reduction of somewhere between 2017.07 and 2991.13 over the year, with some areas achieving small or no reductions in waste, and others achieving substantial tonnage reduction as seen in Heaton. These figures could amount to a financial saving of between £2.47 and £3.67, respectively, per household per year, when taking into account all households in the borough (106,032). We therefore recommend that this approach has potential to generate larger cost savings if applied at scale.

How is the new approach being sustained?

With the success of the pilot, Havering Council is considering opportunities to potentially introduce a similar behavioural insights methodology to other areas across the Council as a way of effectively engaging with the residents and communicating in a way that would appeal to them. This could include identifying new waste behaviours as a result of the pandemic or for introducing a new recycling stream. Keep Britain Tidy is exploring opportunities for further testing of this waste reduction approach nationally, such as considering how this can be used for wheeled bin services, ultimately leading to the provision of guidance to local authorities looking to implement it. In addition, participating residents are now educated and upskilled on waste prevention with the aim that new waste reduction habits have been formed, leading to sustained change.

Lessons learned

Due to the Coronavirus pandemic, some elements of the pilot could not go ahead as planned. It is suggested that future iterations of the challenge should be trialled over a longer period, as originally intended, and aim to understand the extent to which any changes in waste behaviour are sustained in the longer term, via resident perception surveys and longer term waste monitoring. The waste events planned to take place in the high engagement area were also cancelled, one due to the pandemic and two due to a lack of interest from residents. For this reason, both target rounds in the pilot received the same level of communication and engagement as each other. It is therefore not known the extent to which this increased engagement would have impacted on results, as compared to the basic communications package. This too should be explored in future pilots.

In addition to the lack of interest in waste events, the two resident meetings at the outset of the challenge had a low turnout. It is suggested that future initiatives should review whether such events are necessary, and if they do go ahead, how they are advertised and how they can be made more appealing to residents, particularly those in high waste-producing areas.

The waste reduction packs delivered to residents at the outset of the challenge were too large to be posted through doors or letterboxes as originally intended and therefore were left on the doorstep of properties in the target areas. It is recommended that the waste packs would have been more impactful and salient if they had been delivered through letterboxes, and similar future initiatives should therefore ensure this by using smaller sized boxes.

Finally, in understanding how this approach can be applied more widely, future pilots should also explore how the intensive monitoring and level of communications can be scaled up to a larger target area and test the challenge in an area with a wheeled bin service.


Natalie Naor, 
Public Realm Project Officer, London Borough of Havering

[1] This figure is calculated on the basis that the increase in waste tonnages seen in Rainham was due to external factors and not a direct result of the Two Bag Challenge. We conclude that we do not understand the level of impact, if any, in this area and so for the purpose of a cost savings analysis we have assumed there was no change to waste tonnages in Rainham & Wennington.