Litter Monitoring Results

Latest update: January 2017

Food-related packaging and toiletry products are having a huge impact on the River Thames, according to our latest research.

Between Nov 2014 and Dec 2016, our volunteers have conducted 56 detailed litter surveys to uncover the type of litter present in London’s iconic river. The survey method was developed in partnership with Marine Conservation Society (MCS) to help address the lack of evidence on how much litter is entering the river, how it is getting there and what impact it may be having.

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Key findings and recommendations

  • Products (i.e. the items that consumers actually buy) represent only 25% of the litter identified, most of which is plastic designed for single use, with the remaining 75% all packaging. Thus, the use of biodegrable materials in disposable products and for packaging could have a huge impact on the Thames.
  • The top ten items account for more than two thirds of the litter, indicating that a targeted approach on these items is needed. The successful campaign to urge manufacturers to return to making cotton bud sticks from cardboard rather than plastic shows what can be achieved.
  • Plastic drink bottles and their lids represent 10% of all litter found in the river, highlighting the urgent need for a bottle deposit scheme. Almost half of these bottles are still mineral water bottles – by far the biggest single category of drink bottle. We therefore strongly support the call to bring back water fountains to London (see the #OneLess campaign).
  • Wet wipes flushed down toilets are accumulating in huge numbers on the foreshore, presenting a massive environmental problem. Urgent action is needed to better label these products and to educate the public on how to dispose of them properly.

Origins of litter

Food related packaging is the most commonly found litter type on the Thames foreshore, representing almost two out of three pieces of identifiable litter.

Furthermore, just seven food items represent 60% of the litter (see Top 10 items found). The proportion of food related items reported is slightly lower than the 74% recorded in July 2016; this is because of an increase in effort in the counting of wet wipes (see Wet wipes in the Thames) since July.

However, it is also due to the creation of two new litter categories that have been identified.

Toiletries and medical items are the second most common litter type in the Thames; the vast majority of these items are thought to find their way onto the Thames foreshore via sewage overflows during rainfall.

Construction and domestic related litter have been observed for the first time as small but significant sources of litter.

The identification of new litter types shows the Thames River Watch volunteers are improving their ability to identify the range of items in the river. This is vital because understanding the origin of litter can help establish us how it enters into the Thames. An example of this improved identification amongst volunteer is the reporting of the packaging peanuts (foam pieces used for packing fragile items); where these were once marked as ‘unidentified foam,’ they now have a name and are recognised as the most common item under ‘Domestic products’. Equally, we have increasingly been recording fragments of building insulation – the most common item associated with construction – over the past 6 months, due probably to improved identification.

Packaging versus products

Products (i.e. the items that consumers are actually buying) represent only 25% of identifiable litter, with the remaining 75% all packaging. More than half of these products are cotton bud sticks, wet wipes and sanitary towels; items that are designed for single use before disposal.

This chart builds on the Origins of Litter data but also differentiates between the role that the item performs; i.e. whether it is purchased for its own right (such as a cigarette) or simply to protect a particular product (such as a plastic drink bottle). Food related litter is almost exclusively packaging and makes up the bulk of the items found. Toiletry products are a significant section but most of these designed to be used only once.

Top 10 items found

The top 10 most numerous items of litter account for more than two thirds of the items counted by Thames River Watch volunteers. Efforts to prevent these ten items from entering the river will go a long way to cleaning up the Thames.

In total our Thames River Watch volunteers counted over 13,000 pieces of litter from the Thames foreshore between 2014 and 2016 (excluding unidentified plastic <2.5 cm in length and unidentified polystyrene pieces which are quantified differently).

The most common item found on the foreshore is plastic food wrappers (20% of all items) whilst three other well-known culprits populate the top 5 most common items: cotton bud sticks (10%), drinks bottles and their lids (10%) and take-away containers (8%).

However, unidentified pieces of plastic greater than 2.5cm (6% of all items) are a surprise entry to the top 5; representing those items that are either sufficiently unusual so as not to be recognised or (more worryingly) broken down beyond recognition.

*Wet wipes are likely to be under-represented in our Thames River Watch litter survey data thus far, due to the difficulty in counting them (see section below on wet wipes).

Plastic drink bottles found in the Thames

Still mineral water represents by far the most common drink bottle in the Thames, making them one of the worst plastic pollutants in the river.

Plastic drink bottles and their lids are the third most common item found in our regular litter surveys. Once their surveys have been completed, our volunteers also conduct whole beach counts of drink bottles in order to track more confidently the change in bottle numbers over time. During the month of September, for instance, over 4,000 bottles were removed across London; 2,500 of which were recorded in a single day in the first ever co-ordinated attempt to record and remove all the bottles from London.

Wet wipes in the Thames

Wet wipes are finding their way into the Thames in huge numbers during sewage overflows caused by rainfall and are forming a part of large mounds at certain “hotspot” sites across London.


Wet wipes are in the top ten items found on the foreshore of the Thames, but they are grossly under-represented in the data. This is because (A) the sites where they typically occur in high densities are difficult to access and (B) the wet wipes become wound together in large masses (not unlike a kitchen mop) that are very difficult to disentangle. They are partly made from plastic compounds (such as polyester and polyethylene) and are therefore a significant contributor of plastic to the river.

The highest concentration recorded to date was on the south side of Hammersmith Bridge where 150 wet wipes were found in 1m2, counting those found on the surface only.

Photo: Wet wipes found in 1m2 of foreshore on the southside of Hammersmith Bridge after being washed and disentangled

Volunteer effort

The data presented above is thanks to the extraordinary dedication of our 164 Thames River Watch surveyors. Between them they have carried out 1,141 water quality surveys and 56 litter surveys.

The overall number of volunteer effort has grown by almost 50% over the last year, due in part to the increased effort in training and supporting litter monitoring which takes a lot longer than water quality monitoring.


Surveys were conducted at various locations along the Thames categorised as:

‘Sinking hotspots’ – litter accumulates on the bed of the river and deposits at the low tide line. These hotspots often show consistent numbers of microplastics in the sand and mud and are also where most wet wipes, sanitary products and plastic bags are found.

‘Floating hotspots’ – litter accumulates at the top of the foreshore by floating up with the tide. These sites often accumulate densities of plastic bottles, polystyrene and food packaging.

‘Foreshore reaches’ – These are more typical areas of Thames foreshore which do not attract large densities of litter but where litter is certainly present. We consider foreshore reaches to be more indicative of the litter along the Thames as a whole. These sites will often contain a mixture of sinking and floating litter items.

Using the maps: Select the litter category you are interested in by clicking the headers below. To display results, hover the mouse on a point or view the full survey by clicking on a data point. A colour-coded key is below the map.

This category refers to any litter that originates from the food industry. It is further categorised by material, including: plastic (e.g. drink bottle, food wrapper); metal (e.g. drink cans, bottle top); polystyrene (e.g. takeaway container, cups); or other (e.g. glass, paper, wood, cork).

Non-food related packaging is a separate category that includes plastic shopping bags, refuse sacks, and bottles/containers not used for food (e.g. cosmetics, pharmaceutical).

This category refers to any litter that is expected to have been discarded down a toilet. This includes baby wipes, sanitary towels, cotton-bud sticks, nappies and syringes.

During our foreshore clean-ups on the Thames, we consistently find fragments of plastic that has already begun to degrade and so cannot be identified. Such plastic fragments are frequently ingested by wildlife and present a significant threat to their health.

Fragments of polystyrene that have begun to degrade are frequently found on the foreshore and present a significant threat to wildlife. Although it is often not possible to identify the source of the polystyrene (e.g. food related or other source), it is important to record the presence and abundance of the material to understand the scale of the challenge they present.