The Grime Line

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This activity gets the young people to think about why it is important to keep our waterways free of litter and pollution.
It will also encourage the young people to consider how unflushable items end up in rivers and canals and the damage this can cause.

Originally sourced from A Million Hands - Water Resource Pack (2015) in partnership with WaterAid


> Two plastic bottles filled with water.
> A piece of toilet paper.
> A wet wipe.
> Grime line images.
> Grime line time labels.


> Explain to the young people that they are going to be thinking about waterways such as canals and rivers locally, and how we are responsible for making sure that they do not get polluted or contaminated.
> Ask the group to share thoughts on how they dispose of rubbish. You could ask what they do with toilet roll, tissues, wipes, food and so on.
> Ask them what they think ‘FOG’ means. Explain that it is an acronym for Fat, Oil and Grease. Ask them what they or their parent/carer does with fats, oils and grease after cooking.
> Explain that it is really important that FOG is disposed of correctly as it currently causes 75% of drain blockages in the UK. These blockages cause floods in homes and cost a lot of money to unblock.
> Ask the group what they think causes the other 25% of blockages.
> Wet wipes cause the other 25% of drain blockages in the UK. Choose two volunteers to help show why wet wipes cause blockages when flushed down the toilet with the following demonstration:
> Prepare one bottle with toilet paper and water in it and ensure the lid is screwed on tightly. The other bottle should contain a wet wipe with water.
> Give a bottle to each volunteer and tell them what is in each one. Tell them that in a moment they should shake the bottle as hard as they can for one minute. Ask the young people to guess what they think will happen. Once the volunteers have shaken the bottles, put them in a space where everyone can see.

> Compare the difference between the broken down toilet paper and the wet wipe which has remained whole. Reflect on whether this is in line with their predictions and explain that the wet wipes have little filaments of plastic in them which make them really strong and stop them from breaking down as quickly as toilet paper. This means that they end up blocking drains and pipes and getting tangled in machinery used to treat water. For this reason, wipes need to be put in the bin not flushed down the toilet.
> Following on from this, split the young people into two teams, give each team a set of Grime Line game images.
> Working in their teams, each group must try and match the image with the amount of time that they think it takes for that item to decompose in a river. Next, place them in order of the amount of time that they think it will take for the item in the image to break down and decompose, creating a grime line.
> Each group should share their answers.
> The correct order should be revealed by the adult volunteer.
> Ask the young people if they are surprised or shocked by any.
> Ask them what this tells us about flushing items away or throwing them into rivers and canals.
> How do they think this affects us and our environment?
You could follow this activity with the Canal Water Walk, Bin It, Don’t Block It or hand-washing Poster Activity.

Grime line answers
3-4 weeks: Banana skin.
1 month: Paper bag.
2 months: Cardboard.
1 year: Woolen sock.
50 years: Tinned steel can.
200-500 years (if recycled, it can be reused within 6 weeks): Aluminium can.
550 years: Nappy.
20-1000 years: Plastic bag.
1 million years: Plastic jug.
1+ million years: Glass.
1-2 million years: Polystyrene.


  • A million hands
  • water
  • Wateraid

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