Does anyone know where to get hold of a cheap liner for a large sac (sac's about 75 litres). I don't want the weight of an Ortlieb type of liner, just a large, tough plastic bag of the style you can get in gear shops for small to medium sacs, into which I would put sleeping bag, duvet, spare clothes etc - not the entire content of the sac.
I've tried Tesco: their rubble sac's too short, garden refuse sack too weak.
It would be ideal if it was clear or at least translucent.
Perhaps there are very lightweight nylon liners, but I've not come across any yet.
Thanks.

Many moons ago I used to get used agricultural feed bags from feed merchants/general farm supplies dealers. They were very robust with no 'safety' holes

Get hold of some large plastic sacks from your local Plumbcenter .I used them and they are strong and long enough to twist and tie at the top.If you ask the lads in the warehouse they'll probably give you a few

We use em at work for bagging sawdust that doesnt get burnt , I shall find out where we buy them , not particularily cheap if I recall ,about £2 a bag .4foot tall about 2 foot 6 in diameter. clear plastic .tough.
Its what I use.

Get nicked and then see if they'll give your stuff back in a large evidence bag afterwards.

Exped sack liners are very light (I would guess lighter than heavy-duty polythene), cost under a tenner, and over time will be more economical than constantly replacing poly-bags.

Even lighter and cheaper, use an Exped dry bag - I can fit sleep bag, trest + spare clothes in a large one easily. Think I paid about £6 for it.

B&Q Rubble Sacks, dead strong, dead cheap. I've used them for years and I still have the exact same ones and they only cost about £1.50 for a pack of 12.

I always use a cheap plastic orange survival bag. They don't last long so I replace it every few months or so depending on use. It works fine and everything inside is also wrapped for added protection. I put my sleeping bag inside an Exped waterproof bag for 100% protection. Seems like a lot of fuss but wet gear is no fun on longer trips and can be dangerous in really bad conditions.
Apparently, Exped do a large 100-120 L model but I have'nt seen one anywhere. One retailer in Ambleside told me that "people don't go backpacking anymore" so he no longer stocks really big rucsack liners !!
Dave Porter